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This conference will focus on recent advances and challenges in GaN and related materials and electronic, switching, and optical devices based on them, including potential applications. An important objective of this conference is to provide a forum for dissemination of the latest results on current and emerging topics in GaN and related materials and devices, as well as paving the way for in-depth discussions among participants. The topics of discussion will include, but not be limited to, scientific and technological advances in all aspects of materials, including bulk GaN, ternaries and quaternaries, heterostructures, micro- and nanostructures, new substrates and new methodologies employed for alternative substrates, materials physics, devices (electronic and optical), device physics, novel devices such as microcavity based ones, processing, and particularly devices with emphasis on light-emitters in the visible and UV regions of the optical spectrum, novel growth techniques, and device reliability.

Topics for presentation and discussion will include but not be limited to:

Epitaxial growth, bulk growth, and growth of nanostructures Defects and doping Optical, electrical, and material characterization III-nitride micro- and nanostructures, photonic integrated devices (PIC), and MOEMS Fundamental physics of III-nitride semiconductors In-plane laser diodes, SLEDs, and VCSEL for the short visible to UV spectral region Electronic devices Visible and UV LEDs, micro-LEDs, and detectors ;
In progress – view active session
Conference 12001

Gallium Nitride Materials and Devices XVII

In person: 24 - 27 January 2022
View Session ∨
  • OPTO Plenary Session
  • 1: Honoring Isamu Akasaki: Joint Session with Conferences 12001 and 12022
  • 2: Growth: Bulk and Epitaxy I
  • 3: Growth: Bulk and Epitaxy II
  • 4: Fundamental Physics and Characterization
  • 5: Degradation
  • 6: VCSEL, Semipolar Laser Diodes, and Single-Photon Emitters
  • 7: In-Plane Laser Diodes I
  • 8: In-Plane Laser Diodes II
  • 9: Photodetectors
  • 10: UV LED I
  • 11: UV LED II
  • Posters-Wednesday
  • 12: (Red) LEDs and Micro LEDs
  • 13: LED Efficiency
  • 14: Nanostructured Devices
  • 15: Electronic and Nanostructured Devices


  • Submissions are accepted through 06-December
  • Notification of acceptance by 20-December

View Call for Papers PDF Flyer
OPTO Plenary Session
In person: 24 January 2022 • 8:00 AM - 10:10 AM PST
8:00 AM: Welcome and Opening Remarks
Sonia M. García-Blanco, Univ. Twente (Netherlands); Bernd Witzigmann, Friedrich-Alexander-Univ. Erlangen-Nürnberg (Germany)

8:05 AM: Announcement of the IBM-SPIE HBCU Faculty Accelerator Award in Quantum Optics and Photonics
Kayla Lee, IBM Research (USA)
Author(s): Hiroshi Amano, Nagoya Univ. (Japan)
In person: 24 January 2022 • 8:10 AM - 8:50 AM PST
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ISAMU AKASAKI, special distinguished professor of Meijo University, and distinguished university professor and emeritus professor of Nagoya University, the pioneer of blue LEDs, and the Nobel Laureate in physics, passed away from pneumonia on Thursday, April 1, 2021 at the age of 92. He was always a real pioneer. He started nitride research in 1967. At that time, blue LED research was an undeveloped area. When he moved from Matsushita Giken Co., Ltd. to Nagoya University in 1981, almost no other organizations attempted to continue with the topic. At that time, the majority of researchers determined that it was very difficult to grow single crystals, and that realizing p-type GaN was impossible. Therefore, many abandoned GaN. According to him, his situation at that time was like “going alone in the wilderness.” Today, the wilderness pioneered by Professor Isamu Akasaki is now a prosperous and fruitful field where many researchers all over the world are gathering and bringing happiness to the people. He liked the term “Frontier Electronics.” In this presentation, in addition to his memorial, today’s frontier electronics will be discussed.
Inverse designed integrated photonics (Plenary Presentation)
Author(s): Jelena Vuckovic, Stanford Univ. (United States)
In person: 24 January 2022 • 8:50 AM - 9:30 AM PST
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Despite a great progress in photonics over the past few decades, we are nowhere near the level of integration and complexity in photonic systems that would be comparable to those of electronic circuits, which prevents use of photonics in many applications. This lag in integration scale is in big part a result of how we traditionally design photonics: by combining building blocks from a limited library of known designs, and by manual tuning a few parameters. Unfortunately, the resulting photonic circuits are very sensitive to errors in manufacturing and to environmental instabilities, bulky, and often inefficient. We show how a departure from this old fashioned approach can lead to optimal photonic designs that are much better than state of the art on many metrics (smaller, more efficient, more robust). This departure is enabled by development of inverse design approach and computer software which designs photonic systems by searching through all possible combinations of realistic parameters and geometries. We also show how this inverse design approach can enable new functionalities for photonics, including compact particle accelerators on chip which are 10 thousand times smaller than traditional accelerators, chip-to-chip on on-chip optical interconnects with error free terabit per second communication rates, and quantum technologies.
Author(s): Andrea Blanco-Redondo, Nokia Bell Labs. (United States)
In person: 24 January 2022 • 9:30 AM - 10:10 AM PST
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In this talk we will discuss how to engineer the dispersion relation of photonic platforms to provide robust propagation of classical and quantum states of light. In the first part, we will unveil how to leverage the interaction of nonlinearity with higher orders of dispersion to create novel types of solitons, wave packets that propagate unperturbed for long distances. These objects have advantageous energy-width scaling laws with respect to conventional nonlinear Schrodinger solitons and show promise for applications in ultrafast lasers and integrated frequency combs. Subsequently, we will cover recent developments in topological quantum photonics. Topological photonics studies topological phases of light and leverages the appearance of robust topological edge states. We will emphasize our experimental demonstration of nonlinearly generated and topologically protected photon pairs and path-entangled biphoton states in silicon waveguide arrays. Further, we will detail our latest experiments demonstrating entanglement between topologically distinct modes, highlighting topology as an entanglement degree of freedom.
Session 1: Honoring Isamu Akasaki: Joint Session with Conferences 12001 and 12022
Session Chairs: Hiroshi Fujioka, Institute of Industrial Science, The Univ. of Tokyo (Japan), Martin Strassburg, OSRAM Opto Semiconductors GmbH (Germany)
Author(s): Robert Davis, Carnegie Mellon Univ. (United States)
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My fondest memory of Professor Akasaki was an afternoon meeting solely with him in his office at Nagoya University in early Spring of 1990. He and his coworkers had just published their now highly cited paper “P-Type Conduction in Mg-Doped GaN Treated with Low-Energy Electron Beam Irradiation (LEEBI). The results and discoveries described in this paper both built upon prior ground-breaking research in collaboration with Professor Amano and served as a launch point for many additional related studies that culminated in the award of the Nobel Prize to both gentlemen. My presentation will provide additional details of our meeting as well as highlight some of Professor Akasaki’s internationally recognized, achievements including measurements of the piezoelectric effects in strained GaInN/GaN heterostructures and related quantum-confined Stark effects in these materials.
Author(s): Motoaki Iwaya, Tetsuya Takeuchi, Satoshi Kamiyama, Meijo Univ. (Japan)
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Professor Isamu Akasaki achieved the GaN-based p-n junction blue LED in 1989, which was said to be "impossible to realize in the 20th century" and "theoretically unfeasible," and was awarded many prizes including the Nobel Prize in Physics 2014. In this presentation, we will review those great achievements of Professor Isamu Akasaki. We will also look back at the Nobel Prize award ceremony and Professor Akasaki's research activities after the invention of the blue LED. Nitride semiconductor materials have many unique physical properties that are different from other semiconductor materials, such as widely tunable bandgap, high quality heterojunctions, and giant polarization effects. Professor Isamu Akasaki used to say that "The nitride semiconductors are the ultimate semiconductor material". He was also actively involved in developing unique devices that controlled and utilized such properties. We would like to give a presentation on such efforts. Then, we would like to discuss the current state and future prospect in the research field of "Nitride Semiconductors" that Professor Akasaki has established.
Author(s): Axel Hoffmann, Technische Univ. Berlin (Germany)
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In 1989, after the first development of p-n junction in GaN-based blue LEDs by Professor Isamu Akasaki many researchers in Europe received GaN samples from him and started to investigate the optical, electrical and structural properties of group-III nitrides. This was an important step to form the first excellent centers for research in the European community. I met Prof. Isamu Akasaki the first time during the Nagoya workshop in 1995. This workshop highlighted the nitride semiconductors compared to the ZnSe competitor at these times. After this meeting and the MRS symposium of nitrides 1996 Prof. Akasaki was one of the driving forces and spirits to establish the international conference of nitride semiconductors. 2000 he founded in Nogoya the international workshop of group – III nitrides. In my talk I will review the impact of Prof. Akasaki on the nitride research in Europe.
Session 2: Growth: Bulk and Epitaxy I
Session Chairs: Piotr Perlin, Institute of High Pressure Physics (Poland), Ronny Kirste, North Carolina State Univ. (United States)
Author(s): Tomasz Sochacki, Institute of High Pressure Physics (Poland)
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Gallium nitride substrates are needed for advanced electronic and optoelectronic devices based on GaN-on-GaN technology. The wafers can be prepared from crystals grown by three main methods: crystallization from gas phase, basic or acidic ammonothermal process or growth from solution of gallium and sodium. In this paper a detailed investigation of the basic ammonothermal growth process is presented. By analyzing the crystallization process on a native seed of a lenticular shape we wanted to answer some basic questions: i/ which crystallographic planes play the most important role (which are formed and which disappear)?; ii/ what is the relation between the growth rates in different crystallographic directions?; iii/ what is the influence of the off-cut of the seed on the growth process?.
Author(s): Mikolaj Amilusik, Marcin Zajac, Tomasz Sochacki, Boleslaw Lucznik, Michal Fijalkowski, Malgorzata Iwinska, Damian Wlodarczyk, Institute of High Pressure Physics (Poland); Ajeesh Somakumar, Andrzej Suchocki, Institute of Physics, Polish Academy of Sciences (Poland); Michal Bockowski, Institute of High Pressure Physics (Poland)
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Co-doping with manganese and carbon was performed in gallium nitride (GaN) grown by halide vapor phase epitaxy (HVPE). The crystallized material was examined in terms of its structural, optical, and electrical properties. Basing on Raman and photoluminescence spectra of the samples it will be presented that in the GaN:Mn,C crystals Mn is in a different electrical state (Mn^(3+/4+)) in comparison to Mn in GaN:Mn (Mn^(2+/3+)). This change is due to the presence of carbon, which forces manganese to change the oxidation state. This phenomenon will be analyzed and confirmed by the examination of the electrical properties of obtained crystals.
Author(s): Russell D. Dupuis, Frank Mehnke, Georgia Institute of Technology (United States); Alec M. Fischer, Arizona State Univ. (United States); Zhiyu Xu, Henri K. Bouchard, Theeradetch Detchprohm, Shyh-Chiang Shen, Georgia Institute of Technology (United States); Fernando A. Ponce, Arizona State Univ. (United States)
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III-Nitride laser diodes (LDs) emitting in the near ultraviolet spectral region can enable various important applications such as high-precision chip-scale atomic clocks. However, III-N LDs emitting near 369nm suffer from material and heterostructure design challenges including stress-induced layer cracking and p-type doping limitations. We will present a detailed study on the influence of the Al mole fraction and thickness on the occurrence of surface cracks of heterostructures using nonplanar growth by metalorganic chemical vapor deposition on macro-patterned GaN/sapphire templates and bulk GaN substrates. Data on the nonplanar growth of full III-N UV LD structures will be presented.
Author(s): Kentaro Nagamatsu, Shota Tsuda, Takumi Miyagawa, Reiya Aono, Tokushima Univ. (Japan); Hideki Hirayama, Tokushima Univ. (Japan), RIKEN (Japan); Yuusuke Takashima, Yoshiki Naoi, Tokushima Univ. (Japan)
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In this study, we fabricated MOVPE of high gas flow velocity with separation in space between the Al source and N source by imitation of jet engine. As a result, the crystal growth in AlN by MOVPE was succeed high temperature growth until 1750℃ without adduct formation. The growth rate is decreasing exceed temperature of 1650℃ by desorption, the relationship the value of growth rate and the temperature is similar tendency to estimate by thermodynamic calculation in previous study. The crystalline quality of high temperature grown AlN was improved at the unintentional doped impurities concentration, dislocation densities, and surface roughness.
Session 3: Growth: Bulk and Epitaxy II
Session Chairs: Russell D. Dupuis, Georgia Institute of Technology (United States), Tomasz Sochacki, Institute of High Pressure Physics (Poland)
Author(s): Andreas Popp, Forschungsverbund Berlin e.V. (Germany)
Author(s): Ronny Kirste, Seiji Mita, Jordan Almeter, Ramon Collazo, Zlatko Sitar, North Carolina State Univ. (United States)
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We demonstrate that MOCVD growth of AlGaN on GaN via facet controlled epitaxial lateral overgrowth (FACELO) allows for the growth of thick, relaxed, doped, c-oriented layers. The process includes patterning of the substrate, growth of GaN with pyramidal planes, and epitaxy of AlGaN. We show that AlGaN films with 30% Al-content and several microns of thickness can be grown. The fully coalesced films have a clean, crack free surface with an AFM RMS of 1 nm in a 10x10 μm2 area. Dislocation density is investigated via XRD and etch-pit-density and a dislocation density ranging 106 – 108 cm-2 is measured.
Author(s): Malgorzata Iwinska, Pawel Prystawko, Institute of High Pressure Physics (Poland); Andrzej Taube, Lukasiewicz Research Network (Poland); Kacper Sierakowski, Institute of High Pressure Physics (Poland); Rafal Jakiela, Institute of Physics, Polish Academy of Sciences (Poland); Michal Bockowski, Institute of High Pressure Physics (Poland)
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Silicon diffusion process was investigated in GaN layers crystallized by metal-organic vapor phase epitaxy (MOVPE) on native ammonothermal substrates of the highest structural quality. N-type (Si-doped) and p-type (Mg-doped) layers were implanted with Si and treated with ultra-high-pressure annealing. The morphology of the layers was examined at each step by optical microscopy and atomic force microscopy. The crystallographic structure was evaluated by X-ray diffraction measurements. The diffusion of Si was analyzed basing on depth profiles from secondary ion mass spectrometry. Temperature-dependent diffusion coefficients, pre-exponential factors, and activation energies for Si diffusion in n-type and p-type MOVPE-GaN were determined and compared.
Author(s): Muzafar Rather, Loganathan Ravi, Shih-Ming He, Chao-Chia Cheng, Ching-Yuan Su, Jen-Inn Chyi, National Central Univ. (Taiwan)
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III-nitride semiconductors, GaN, in particular, had played an important role in optoelectronic and electronic devices through the advancement of heteroepitaxy. These heteroepitaxy processes have been well established on single-crystalline substrates, such as Si, SiC, and sapphire. However, the mismatch between GaN and these substrates in lattice constant as well as thermal expansion coefficient imposes the limit on device performance and reliability. The search for a better substrate still continues. Here, we report the heteroepitaxy of III-nitride semiconductors on polycrystalline and amorphous substrates using a layered two-dimensional material as a buffer and seed layer. The two-dimensional material on a polycrystalline or amorphous substrate mitigates the lattice mismatch conditions, and shields the random oriented atomic registry of polycrystalline or amorphous substrates to promote single-crystalline hetroepitaxy of III-nitrides without any requisites from the substrate itself.
Author(s): Shiori Yamamura, Yoshiya Miyamoto, Meijo Univ. (Japan); Naoki Sone, Koito Manufacturing Co., Ltd. (Japan); Weifang Lu, Renji Okuda, Kazuma Ito, Yukimi Jinno, Nanami Nakayama, Sae Katsuro, Satoshi Kamiyama, Tetsuya Takeuchi, Motoaki Iwaya, Meijo Univ. (Japan)
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Current injection through tunnel junctions (TJs) can enhance the external quantum efficiency of nanowire (NW) and multi-quantum-shell-based optical devices, compared. However, control of the impurity concentration profile is difficult in such tiny structure. In this study, we show a simple evaluation method of impurities in TJs growing flatly on m-plane GaN substrates, which have the same crystalline orientation as the luminescent surface of MQS/NWs. It was found to decrease the differential resistance by increase the concentration of Mg in p^(++)-GaN in the TJ.
Author(s): Muhammed Aktas, Institute of High Pressure Physics (Poland); Dario Schiavon, Anna Kafar, Szymon Stanczyk, Institute of High Pressure Physics (Poland), TopGaN Ltd. (Poland); Krzysztof Gibasiewicz, Institute of High Pressure Physics (Poland); Szymon Grzanka, Piotr Perlin, Institute of High Pressure Physics (Poland), TopGaN Ltd. (Poland)
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In this work, we study the optoelectrical properties of nitride LED structures employing polarization doping for the p-type layers. We compare standard Mg-doped, partially doped, and undoped AlGaN p-type layers. The electrical properties of these samples are similar, proving the successful use of polarization doping. The optical measurements suggest that doping of the electron blocking layer is required for preserving good light emission efficiency. We also studied our samples at lowered temperatures and observed no freeze-out region down to 77K. For top metal contact, sub contact doping is indispensable because the intrinsic top layer causes the Schottky barrier.
Session 4: Fundamental Physics and Characterization
Session Chairs: Ryota Ishii, Kyoto Univ. (Japan), Michael A. Bergmann, Chalmers Univ. of Technology (Sweden)
Author(s): Jonas Lähnemann, Uwe Jahn, Vladimir M. Kaganer, Paul-Drude-Institut für Festkörperelektronik (Germany); Karl K. Sabelfeld, Anastasya E. Kireeva, Institute of Computational Mathematics and Mathematical Geophysics (Russian Federation); Carsten Pfüller, Caroline Chèze, Klaus Biermann, Raffaella Calarco, Oliver Brandt, Paul-Drude-Institut für Festkörperelektronik (Germany)
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For the quantitative analysis of cathodoluminescence maps and related techniques, an accurate knowledge of the generation volume of electron-hole pairs is mandatory. The scattering cascade for incident electrons is commonly determined from Monte-Carlo simulations. In an experimental study on GaN and GaAs, we find the generation volume to be larger than expected from the simulations. In particular, we report an increase of the generation volume with decreasing sample temperature – in contrast to the so far assumed temperature independence. This finding is explained in terms of electron-phonon interactions during the energy relaxation of hot carriers.
Author(s): Vitaliy Avrutin, Natalia Izyumskaya, Umit Ozgur, Hadis Morkoc, Virginia Commonwealth Univ. (United States)
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Recent breakthroughs in n-type doping of GaN, which led to the material with electron concentration up to the mid-10^20 cm-3 range and mobility reaching 100 cm2/(Vs), logically call for the evaluation of this material for near-IR tunable plasmonics. Moreover, its robustness, biocompatibility, developed growth techniques, and possibility of combining with III-nitride-based light-emitters and detectors make GaN particularly attractive for variety of plasmonic applications. In this contribution we discuss the potential of GaN for plasmonic applications with taking into consideration recent advancements in the growth of heavily doped n-type material, its fundamental electronic properties, and features of the band structure. Special emphasis is given to losses and potential applications in integrated nonlinear optics.
Author(s): Rinat Yapparov, KTH Royal Institute of Technology (Sweden); Yi Chao Chow, Cheyenne Lynsky, Feng Wu, Shuji Nakamura, James S. Speck, Univ. of California, Santa Barbara (United States); Saulius Marcinkevicius, KTH Royal Institute of Technology (Sweden)
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V-defects play an important role in carrier recombination in polar InGaN quantum wells (QWs). Here we report a study of V-defects in QWs emitting from 410 to 570 nm performed by time-resolved near-field optical spectroscopy. In V-defect regions, the radiative carrier lifetime is longer and the nonradiative - shorted than in defect free regions, showing strong spatial variations of the internal quantum efficiency (IQE). The areas with the low IQE, however, are limited to regions just above the dislocations (~2% of the total sample area) showing that the nonradiative recombination at dislocations is not a major factor determining the IQE.
Author(s): Conny Becht, Ulrich T. Schwarz, Technische Univ. Chemnitz (Germany); Michael Binder, Bastian Galler, Jürgen Off, Maximilian Tauer, Alvaro Gomez-Iglesias, Heng Wang, Martin Strassburg, OSRAM Opto Semiconductors GmbH (Germany)
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µPL and µEL pinhole scans of an InGaN MQW and SQW show PL spots with a FWHM of up to 1.5 µm. The FWHM of the excitation source is in contradiction 220 nm small. We therefore conclude a lateral diffusion over several micrometers taking place. A simple rate equation model was used to fit the observed PL spots over distance. The model includes the recombination rate to be dependent of the charge carrier density using the ABC model. We observe for the MQW and SQW sample a diffusion coefficient of 3 cm^2 s^-1 and 3.2 cm^2 s^-1, respectively.
Author(s): Rinat Yapparov, KTH Royal Institute of Technology (Sweden); Cheyenne Lynsky, Shuji Nakamura, James S. Speck, Univ. of California, Santa Barbara (United States); Saulius Marcinkevicius, KTH Royal Institute of Technology (Sweden)
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Efficient operation of light emitting devices based on InGaN multiple quantum wells (MQWs) requires a uniform interwell carrier distribution and low nonradiative recombination. The uniform distribution may be achieved by speeding-up the interwell transport via lowered barriers (InGaN instead of GaN). However, the InGaN barriers might increase the nonradiative recombination. Therefore, in quest of optimal structure parameters, the interwell transport should be studied in parallel with the recombination. In this work, this has been performed for (In)GaN/In₀.₁₂Ga₀.₈₈N MQW structures by time-resolved photoluminescence. It was found that the optimal trade-off is achieved for barriers with 4% In.
Session 5: Degradation
Session Chairs: Hideto Miyake, Mie Univ. (Japan), Dong-Pyo Han, Meijo Univ. (Japan)
Author(s): Shigetaka Tomiya, Sony Corp. (Japan), Tokyo Institute of Technology (Japan); Yuya Kanitani, Sony Corp. (Japan)
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Improving crystal quality and reducing crystal defects is essential to improve the properties and reliability of GaN-based optical devices. For this purpose, it is important to understand the crystallinity and defects fully. In the presentation, we discuss issues analyzed using transmission electron microscopy and laser-assisted 3D atom probe for various types of grown-in defects in epitaxial layers, compositional modulation in GaInN layers, process-induced defects, and degraded devices. We then, discuss the degradation mechanisms of the devices.
Author(s): Nicola Roccato, Francesco Piva, Carlo De Santi, Riccardo Brescancin, Kalparupa Mukherjee, Matteo Buffolo, Univ. degli Studi di Padova (Italy); Camille Haller, Jean-Francois Carlin, Nicolas Grandjean, Ecole Polytechnique Fédérale de Lausanne (Switzerland); Marco Vallone, Alberto Tibaldi, Francesco Bertazzi, Michele Goano, Politecnico di Torino (Italy); Giovanni Verzellesi, Univ. degli Studi di Modena e Reggio Emilia (Italy); Gaudenzio Meneghesso, Enrico Zanoni, Matteo Meneghini, Univ. degli Studi di Padova (Italy)
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Defects have a fundamental role in determining the electro-optical characteristics and in the efficiency of InGaN light-emitting diodes (LEDs). However, modeling their effect on the electrical characteristics of the LED is not straightforward. In this paper we analyze the impact of the defects on the electrical characteristics of LEDs: by simulations, we show that defects have a fundamental impact on the current voltage characteristic of LEDs. For the first time, we use in simulations the defect parameters extracted from SSPC. In this way, we can reproduce with great accuracy the current-voltage characteristics of InGaN LEDs in a wide current range.
Author(s): Lukas Uhlig, Conny Becht, Technische Univ. Chemnitz (Germany); Erik Freier, Ji-Hye Kang, Veit Hoffmann, Christoph Stölmacker, Sven Einfeldt, Ferdinand-Braun-Institut (Germany), Leibniz-Institut für Höchstfrequenztechnik (Germany); Ulrich T. Schwarz, Technische Univ. Chemnitz (Germany)
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Degradation of InGaN-based laser diodes after some time of operation appears usually as raised threshold current, lower slope efficiency, or increased voltage. We investigate stressed and non-stressed laser diodes using micro-electroluminescence (µEL) and micro-photoluminescence (µPL). In µEL, the stressed device exhibits darker regions, which are correlated with a red-shifted emission. Both observations indicate a lower carrier density in these darker areas. Our µPL measurements do not suggest regions of increased defect density or stronger nonradiative recombination in the stressed diodes. So, we observe inhomogeneous pumping of the active region that can be explained by current path formation from non-uniform hydrogen distribution.
Author(s): Alessandro Caria, Carlo De Santi, Marco Nicoletto, Matteo Buffolo, Univ. degli Studi di Padova (Italy); Xuanqi Huang, Houqiang Fu, Hong Chen, Yuji Zhao, Arizona State Univ. (United States); Gaudenzio Meneghesso, Enrico Zanoni, Matteo Meneghini, Univ. degli Studi di Padova (Italy)
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We submitted GaN-based MQW solar cells to optical stresses under short-circuit conditions at different temperatures. We performed two step-stress experiments at 35 °C and 175 °C, increasing optical power from 47 to 375 W/cm2: the first caused almost no degradation, the second caused a decrease in device operating parameters. We performed several 100 hours constant optical power (113 W/cm2) stresses at 95, 135 and 175 °C. We found an increase in degradation (decrease in open-circuit voltage and efficiency) by increasing temperature, which can be attributed to defect generation mechanisms in the semiconductor outside the quantum wells.
Session 6: VCSEL, Semipolar Laser Diodes, and Single-Photon Emitters
Session Chairs: Mitsuru Funato, Kyoto Univ. (Japan), Yoshio Honda, Nagoya Univ. (Japan)
Author(s): Jared Kearns, Tatsushi Hamaguchi, Kentaro Hayashi, Maho Ohara, Tomohiro Makino, Maiko Ito, Noriko Kobayashi, Tatsuro Jyokawa, Eiji Nakayama, Shouetsu Nagane, Koichi Sato, Yuki Nakamura, Sony Corp. (Japan); Yukio Hoshina, Sony Shiroishi Semiconductor Inc. (Japan); Yuya Kanitani, Seiji Kasahara, Susumu Kusanagi, Yoshihiro Kudo, Rintaro Koda, Noriyuki Fuutagawa, Sony Corp. (Japan)
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Long-cavity VCSELs with curved mirrors have been achieving good results in recent years with demonstrations of threshold currents less than 1 mA for devices with blue and green emission. One issue associated with using a long cavity has been in the introduction of longitudinal mode instability that is not typically seen in VCSEL devices. Here, we present the use of a filtering mirror to achieve single longitudinal mode lasing up to > 100 kA/cm2. The highly varying reflectivity of the mirror introduces significant loss to adjacent longitudinal modes, and thereby stabilizes the lasing mode.
Out of the blue: UV VCSELs (Invited Paper)
Author(s): Åsa Haglund, Filip Hjort, Chalmers Univ. of Technology (Sweden); Johannes Enslin, Technische Univ. Berlin (Germany); Michael A. Bergmann, Chalmers Univ. of Technology (Sweden); Munise Cobet, Giulia Cardinali, Nando Prokop, Technische Univ. Berlin (Germany); Lars Persson, Chalmers Univ. of Technology (Sweden); Tim Kolbe, Ferdinand-Braun-Institut gGmbH, Leibniz-Institut für Höchstfrequenztechnik (Germany); Johan Gustavsson, Chalmers Univ. of Technology (Sweden); Joachim Ciers, Chalmers Univ of Technology (Sweden); Tim Wernicke, Michael Kneissl, Technische Univ. Berlin (Germany)
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In recent years, there has been tremendous improvement in the performance of blue-emitting vertical-cavity surface-emitting lasers (VCSELs) and they are now on the cusp of commercialization. We will summarize state-of-the-art results and outline the main challenges in extending the emission wavelength into the ultraviolet (UV). Our method to simultaneously achieve high-reflectivity mirrors and good cavity length control by selective electrochemical etching has been essential to demonstrate the world’s first UV-B VCSEL. The use of dielectric mirrors, where one material has a negative thermo-optical coefficient, counteracts the inherent red-shift of the resonance wavelength, enabling a temperature-stable emission.
Author(s): Haojun Zhang, Hongjian Li, Panpan Li, Shuji Nakamura, Steven P. DenBaars, Univ. of California, Santa Barbara (United States)
Author(s): Max Meunier, Ctr. de Recherche sur l'Hétéro-Epitaxie et ses Applications (France); Mu Zhao, Zhengzhi Jiang, Nanyang Technological Univ. (Singapore); Sébastien Chenot, Philippe De Mierry, Mathieu Leroux, Ctr. de Recherche sur l'Hétéro-Epitaxie et ses Applications (France); Olivier Alibart, Institut de Physique de Nice (France); Weibo Gao, Nanyang Technological Univ. (Singapore); Jesus Zuniga Perez, Ctr. de Recherche sur l'Hétéro-Epitaxie et ses Applications (France)
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Single photon emitters in GaN have aroused great interest as they operate at room temperature, and can emit both in the telecom and near-IR (typically around 700 nm) ranges. We study the growth conditions that enable their presence in GaN, and address the fabrication of different GaN photonic circuits at the corresponding operating wavelengths. In particular, we discuss the fabrication of bullseye nano-antennas, as well as of a more complex system that includes a waveguide cavity surrounded by two asymmetric Distributed Bragg Reflectors, which enable the coupling to an auxiliary waveguide terminated by a grating out-coupler.
Session 7: In-Plane Laser Diodes I
Session Chairs: Maki Kushimoto, Nagoya Univ. (Japan), Ulrich T. Schwarz, Technische Univ. Chemnitz (Germany)
Author(s): Yoshitaka Nakatsu, Yoji Nagao, Tsuyoshi Hirao, Kazuma Kozuru, Tatsuya Kanazawa, Shingo Masui, Eiichiro Okahisa, Tomoya Yanamoto, Shin-ichi Nagahama, Nichia Corp. (Japan)
Author(s): Tetsuya Takeuchi, Satoshi Kamiyama, Motoaki Iwaya, Meijo Univ. (Japan)
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We will provide our results on low resistive GaN-based tunnel junctions and optoelectronic devices grown by MOVPE. In order to obtain low resistive GaN-based tunnel junctions grown by MOVPE, we have pointed out that high impurity concentrations were required. We also found that large overlap with Mg/Si and small Mg segregation were key factors. The lowest contact resistivity value in our GaN tunnel junctions is now less than 1e-4 Ωcm2 over 8 kA/cm2. We have used such low GaN-based tunnel junctions in edge-emitting laser diodes and VCSELs, showing comparable laser characteristics to standard p-contact lasers.
Author(s): Anna Kafar, Szymon Stanczyk, Institute of High Pressure Physics (Poland), TopGaN Ltd. (Poland); Dario Schiavon, Institute of High Pressure Physics (Poland), TopGaN Ltd. (Poland); Piotr Perlin, Institute of High Pressure Physics (Poland), TopGaN Ltd. (Poland)
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Nowadays, there is a growing need for light-sources meeting seemingly contradictory requirements such as very narrow emission spectrum and high optical power or high quality of the light beam combined with a broad emission spectrum. These specific requirements trigger the development of optoelectrical elements such as superluminescent diodes (SLD) and semiconductor optical amplifiers (SOA). In this presentation, we will review the basic work principles of SLDs and SOAs as well as discuss the important challenges such as: suppression of the feedback from the device facets, reduction of gain saturation, broadening of SLD emission spectra. We will also analyze the limits related to self-heating.
Author(s): Ryan Anderson, Univ. of California, Santa Barbara (United States)
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GaN based edge emitting laser diodes typically use AlGaN or InGaN for mode confinement in waveguide cladding layers. Defect formation, high voltage, and lifetime issues limit the possible thickness and composition. Nano-porous GaN is a lattice matched, high index contrast material under investigation to replace AlGaN or InGaN for optical confinement. This opens up new designs to improve power and efficiency in GaN laser diodes. Electrically injected lasers have been fabricated using nano-porous GaN cladding, leading to a reduction in threshold current density at a cost to efficiency. Methods to reduce excess loss and improve heat dissipation will be discussed.
Session 8: In-Plane Laser Diodes II
Session Chairs: Anna Kafar, Institute of High Pressure Physics (Poland), Tetsuya Takeuchi, Meijo Univ. (Japan)
Author(s): Maki Kushimoto, Ziyi Zhang, Yoshio Honda, Leo J. Schowalter, Chiaki Sasaoka, Hiroshi Amano, Nagoya Univ. (Japan)
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Deep-ultraviolet laser diodes have achieved pulsed lasing at room temperature by improving the crystal quality and establishing a hole injection method using polarization doping techniques. In the initial demonstration, the threshold current density was very high at 25kA/cm2, which is a major barrier to continuous-wave lasing. The reason for this high threshold current density was found to be process-induced non-uniformity of emission. By suppressing this non-uniformity through LD device design, we were able to significantly reduce the threshold current density to about 12 kA/cm2.
Author(s): Motoaki Iwaya, Meijo Univ. (Japan); Sho Iwayama, Meijo Univ (Japan), Mie Univ. (Japan); Tetsuya Takeuchi, Satoshi Kamiyama, Meijo Univ. (Japan); Hideto Miyake, Mie Univ. (Japan)
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UV-B laser diodes are expected to be applied to medical and processing fields. In this presentation, we report on the our recent progress of AlGaN-based UV-B laser diodes. First, we discuss the reduction of the threshold current to achieve CW operation. In particular, by using a refractive-index waveguide structure with a ridge structure, we have realized the device with a low threshold current of 85 mA. The detailed characteristics of the device will be explained in detail in this report. We are also investigating how to increase the output power. When we measure the optical output power of our UV-B laser diodes with a power meter, we get a value of about 20-35 mW, but high current operation is essential to achieve high output power. In order to achieve this, it is desirable to realize a vertical conduction device, and we are currently developing a laser lift-off technology for AlGaN. I would like to discuss the details of this technology.
Author(s): Piotr Perlin, Anna Kafar, Szymon Stanczyk, Dario Schiavon, Lucja Marona, Institute of High Pressure Physics (Poland)
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Recently emerged “quantum technologies” motivate researchers and engineers to develop a specific class of light sources. The expected devices should emit spectrally narrow and tunable light with excellent beam properties. Semiconductor laser diodes are the light source of choice for these applications. InGaN laser diodes, emitting in the visible part of the spectrum, should play very important role in these applications. Within this presentation we will describe InGaN external cavity laser diodes, semiconductor optical amplifiers and distributed feedback lasers. We will discuss the progress in development of these devices as well as main physical and technological challenges.
Author(s): Dominic J. Kunzmann, Lukas Uhlig, Technische Univ. Chemnitz (Germany); Anna Kafar, Szymon Stanczyk, Piotr Perlin, Institute of High Pressure Physics (Poland), TopGaN Ltd. (Poland); Ulrich T. Schwarz, Technische Univ. Chemnitz (Germany)
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We investigate the lateral near field of blue laser diodes with 10 µm broad ridges in pulsed conditions. While scanning the near field step by step, with the help of a streak camera we observe complex dynamics due to lateral-longitudinal mode competition, wavelength shifts and lateral mode switching. Additionally, a high-resolution spectrometer enables us to differentiate between the different mode combs which form the longitudinal mode spectrum. We observe filling of the gain volume and a spectral broadening with increasing current, as well as a slight asymmetry and an inhomogeneous lateral mode pattern.
Author(s): Thiago Melo, Dennis M. Van Den Broeck, Phillip Skahan, Sang Ho Oh, Curt Dvonch, Qiyuan Wei, Alexander Sztein, Melvin McLaurin, James Raring, KYOCERA SLD Laser, Inc. (United States)
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We report on state-of-the-art performance in violet, multi-mode, edge-emitting laser diodes fabricated on semi-polar oriented GaN substrates. Using these novel crystal orientations, we demonstrate high-power and high-efficiency continuous-wave laser operation. We report on violet laser diodes achieving continuous-wave output powers with peak wall-plug-efficiencies above 40% and optical output powers above 5 W at wavelengths between ~405 and ~415 nm. To the best of the author's knowledge, these wall-plug-efficiencies represents the highest reported to date for a multi-mode GaN diode laser emitting in the range of 400-410 nm. These InGaN-based laser-diodes will offer dramatic improvements in performance, size, weight, and cost of conventional solid-state and gas-based violet laser sources for use in defense, medical, and materials processing applications.
Session 9: Photodetectors
Session Chairs: Andreas Popp, Forschungsverbund Berlin e.V. (Germany), Thiago Melo, Kyocera SLD Laser (United States)
Author(s): Russell D. Dupuis, Hoon Jeong, Minkyu Cho, Zhiyu Xu, Shyh-Chiang Shen, Theeradetch Detchprohm, A. Nepomuk Otte, Georgia Institute of Technology (United States)
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Solar-blind (<280nm) deep-ultraviolet (DUV) avalanche photodetectors (APDs) are of importance in various applications such as quantum communication, biomedical, defense, and non-line-of-sight (NLOS) communication. This makes the detectors from AlxGa1-xN materials attractive for such applications owing to their wide direct-bandgap characteristics. In this work, top-illuminated DUV Al0.6Ga0.4N p-i-n APD structures were designed, grown by metalorganic chemical vapor deposition on bulk AlN substrates, and fabricated. The devices showed distinctive avalanche breakdown behavior, with breakdown voltages of -150V, and low-leakage current density of <10-8A/cm2. The peak spectral response is 141mA/W at the wavelength of 245nm under 0V.
Author(s): George T. Wang, Keshab R. Sapkota, A. Alec Talin, Francois Leonard, Sandia National Labs. (United States); Barbara A. Kazanowska, Univ. of Florida (United States); Brendan P. Gunning, Gyorgy Vizkelethy, Sandia National Labs. (United States); Kevin S. Jones, Univ. of Florida (United States)
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We demonstrate novel GaN nanogap vacuum nanoelectronic diodes that operate in air and exhibit ultra-low turn-on voltage, high field emission current, excellent on-off ratio, and promising reliability and radiation hardness. We present experimental and modeling results on the field emission characteristics of these devices at various nanogap sizes and operating pressures. Preliminary results on the fabrication and characteristics of lateral GaN nano vacuum transistors will also be presented. These results provide critical new insights into the behavior of this new class of devices and point to future challenges and opportunities. Sandia National Laboratories is managed and operated by NTESS under DOE NNSA contract DE-NA0003525.
Session 10: UV LED I
Session Chairs: Michael Kneissl, Technische Univ. Berlin (Germany), Matteo Meneghini, Univ. degli Studi di Padova (Italy)
Author(s): Ryota Ishii, Mitsuru Funato, Yoichi Kawakami, Kyoto Univ. (Japan)
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Photoluminescence, electroluminescence, and bias-dependent time-resolved photoluminescence spectroscopies are performed to study the current injection efficiency, internal quantum efficiency, and light external quantum efficiency of 265-nm AlGaN DUV LEDs grown on AlN substrates. The studies showed that the current injection and light extraction efficiencies, and not the internal quantum efficiency, limit the external quantum efficiency. To solve the issue, we revisited the effect of Si-doping in AlN. Our spectroscopic study deduced the significantly lower neutral Si donor bound exciton and Si donor binding energies than those reported, indicating the possibility to realize highly conductive and transparent n-type AlN:Si layers.
Author(s): Michael A. Bergmann, Chalmers Univ. of Technology (Sweden); Johannes Enslin, Martin Guttmann, Luca Sulmoni, Technische Univ. Berlin (Germany); Neysha Lobo-Ploch, Ferdinand-Braun-Institut (Germany), Leibniz-Institut für Höchstfrequenztechnik (Germany); Tim Kolbe, Ferdinand-Braun-Institut (Germany), Leibniz-Institut für Höchstfrequenztechnik (Germany); Tim Wernicke, Technische Univ. Berlin (Germany); Michael Kneissl, Technische Univ. Berlin (Germany), Ferdinand-Braun-Institut (Germany), Leibniz-Institut für Höchstfrequenztechnik (Germany); Åsa Haglund, Chalmers Univ. of Technology (Sweden)
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We will give an overview of different concepts to increase the light extraction efficiency (LEE) of ultraviolet (UV) light-emitting diodes (LEDs) with a focus on thin-film flip-chip (TFFC) devices. Optical simulations show that a TFFC design can greatly improve the LEE with a transparent p-side, reflective contacts, and optimized surface roughening. We will demonstrate UVB-emitting TFFC LEDs based on our fabrication platform for AlGaN thin films with high aluminum content. The fabrication is compatible with a standard LED process and uses substrate removal based on selective electrochemical etching as the key enabling technology.
Author(s): Anjali Harikumar, CEA-IRIG PHELIQS (France); Fabrice Donatini, Institut NÉEL (France); Edith Bellet-Amalric, CEA-IRIG PHELIQS (France); Catherine Bougerol, Institut NÉEL (France); Christophe Dujardin, Stephen T. Purcell, Institut Lumière Matière (France); Eva Monroy, CEA-IRIG PHELIQS (France)
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Recently, there has been an increased interest in germicidal ultraviolet (GUV) lamps for disinfection. Despite extensive studies on GUV LEDs, their efficiency and cost per Watt is still far from that of mercury lamps due to electrical injection issues, among others. Also, the fact that 254 nm radiation is highly carcinogenic and cataractogenic, has motivated research on radiation with shorter penetration (200-230 nm) depth, for non-invasive disinfection. In this study, we propose electron pumped UV lamps as an alternative to LEDs (to tackle electrical issues) in the spectral range 230-330 targeting both wavelength ranges of disinfection and exhibiting IQE ranging from 20%-50%.
Session 11: UV LED II
Session Chairs: Åsa Haglund, Chalmers Univ. of Technology (Sweden), Motoaki Iwaya, Meijo Univ. (Japan)
Author(s): Matteo Meneghini, Francesco Piva, Carlo De Santi, Matteo Buffolo, Nicola Roccato, Riccardo Brescancin, Massimo Grigoletto, Davide Fiorimonte, Nicola Trivellin, Univ. degli Studi di Padova (Italy); Sven Einfeldt, Johannes Glaab, Jan Ruschel, Ferdinand-Braun-Institut (Germany); Norman Susilo, Tim Wernicke, Michael Kneissl, Technische Univ. Berlin (Germany); Gaudenzio Meneghesso, Enrico Zanoni, Univ. degli Studi di Padova (Italy)
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The market of UV LEDs is experiencing a rapid growth, also driven by the need for effective and efficient disinfection systems. Before UV LEDs can be widely accepted by the market, they need to demonstrate a high reliability, with lifetimes of several thousands of hours. Several physical processes may limit the reliability of UVB and UVC LEDs, resulting in a loss in efficiency during long term operation. This presentation aims at discussing the most relevant processes that can lead to the degradation of UVB and UVC LEDs, with the aim of providing a comprehensive overview on the topic.
Author(s): Hideto Miyake, Kenjiro Uesugi, Kanako Shojiki, Shiyu Xiao, Shigeyuki Kuboya, Mie Univ. (Japan)
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We have reported that preparation of the low-threading-dislocation densities (TDDs) AlN film on sapphire by combining face-to-face annealing (FFA) and sputtering of AlN (Sp-AlN). Recent progress in the TDD reduction of the FFA Sp-AlN and the metalorganic vapor phase epitaxy of AlN and AlGaN on the FFA Sp-AlN have been reviewed. The TDD of approximately 4 × 10^7 /cm2 was obtained on the sapphire substrates by the double sputtering and annealing technique with AlN thickness of 600 nm + 600 nm. We demonstrate the performances of UV-C LED fabricated on the FFA Sp-AlN. The peak wavelength obtained was 264 nm whereas the maximum EQE was approximately 2.1%. On wafer LED testing, the output power reached 34 mW under 400 mA operation.
Author(s): Francesco Piva, Davide Fiorimonte, Nicola Trivellin, Carlo De Santi, Matteo Buffolo, Gaudenzio Meneghesso, Enrico Zanoni, Matteo Meneghini, Univ. degli Studi di Padova (Italy)
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In this work, we investigated electrical, optical and spectral degradation mechanisms in a series of commercial UV-C LEDs (275 nm – 280 nm) available on market. We proposed an exhaustive comparison of the sample principal characteristics, studying their evolution when the LEDs were submitted to constant current stress tests at their absolute maximum current. We found: (i) a set of LEDs with a promising L80 of 10000 min, (ii) the presence of parasitic peaks and bands in all devices, and (iii) a substantial thermal droop in all LEDs due to an increase in SRH recombination events during the stress tests.
In person: 26 January 2022 • 6:00 PM - 8:00 PM PST
Conference attendees are invited to attend the OPTO poster session on Wednesday evening. Come view the posters, enjoy light refreshments, ask questions, and network with colleagues in your field.

Poster Setup: Wednesday 10:00 AM – 5:00 PM
View poster presentation guidelines and set-up instructions at
Author(s): Yongkun Sin, Dmitry Veksler, Scott D. Sitzman, Miles Brodie, Zachary Lingley, Neil Ives, The Aerospace Corp. (United States)
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GaN power amplifiers based on AlGaN-GaN high electron mobility transistor (HEMT) technology are produced for defense applications that require high voltage, high power, and high efficiency operation. Many groups have reported various failure mechanisms in GaN HEMTs over the last two decades. However, the fact that no dominant failure mode and mechanism has been identified is a major concern for space applications. For the present study, we continued to investigate RF AlGaN-GaN HEMTs grown on SiC substrate with Ni-Pd-Au Schottky contacts by performing DC bias and temperature stress tests on both pristine and proton-irradiated HEMTs, followed by physical failure analysis.
Author(s): Sergi Cuesta Arcos, Lou Denaix, CEA-Grenoble (France); Quang Minh Thai, Institut Lumière Matière (France); Edith Bellet-Amalric, CEA-Grenoble (France); Stephen T. Purcell, Institut Lumière Matière (France); Le Si Dang, Institut NÉEL (France); Eva Monroy, CEA-Grenoble (France)
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In this work, we study the internal quantum efficiency and the lasing threshold of AlGaN/GaN heterostructures designed for UV laser emission. We discuss the effect of carrier diffusion and carrier localization in the optical properties at low and room temperature. The implementation of a graded-index separate confinement heterostructure results in enhanced carrier collection, reducing the lasing threshold. However, this improvement is not correlated with the internal quantum efficiency of the samples. In addition, the optimization of the cavity facets results in a significant reduction of the mirror losses, leading to a lasing threshold below 100 kW/cm2 under optical pumping at room temperature.
Author(s): Tanbir Kaur Sodhi, Ctr. de Nanosciences et de Nanotechnologies (France); Pascal Chrétien, Lab. Génie électrique et électronique de Paris (France); Laurent Travers, Ctr. de Nanosciences et de Nanotechnologies (France); Frédéric Houzé, Lab. Génie électrique et électronique de Paris (France); Noelle Gogneau, Ctr. de Nanosciences et de Nanotechnologies (France)
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GaN NWs appear as promising candidates to harvest ambient energy sources like mechanical deformations and vibrations due to their superior mechanical and piezoelectric properties. Using an AFM equipped with a home-made modified Resiscope, enabled us to characterize the piezo-conversion capacity of the NWs. Here, we investigate the influence of the measuring circuit on the collection of piezo-charges. We show the importance of the load resistance of the electronics on the piezo-generation capacity of single GaN NWs and especially, we demonstrate the critical role of the nanogenerator resistance, a parameter too often neglected, in the optimization of the measurement.
Author(s): Po-Hsiang Chao, National Yang Ming Chiao Tung Univ. (Taiwan); Jui-Che Chang, Linköping Univ. (Sweden); Weichun Chen, Taiwan Instrument Research Institute (Taiwan); Ching-Lien Hsiao, Jens Birch, Linköping Univ. (Sweden); Ray-Hua Horng, National Chiao Tung Univ. (Taiwan)
Author(s): Shota Tsuda, Takumi Miyagawa, Reiya Aono, Atsushi Tomita, Tokushima Univ. (Japan); Hideki Hirayama, RIKEN (Japan); Yuusuke Takashima, Yoshiki Naoi, Kentaro Nagamatsu, Tokushima Univ. (Japan)
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In this study, rA is investigated by different growth temperature between from 1200℃ to 1650℃ during AlN growth by high temperature metalorganic vapor phase epitaxy (MOVPE). The value of dislocation density calculated by X-ray rocking curve (XRC) fullwidth at half-maximum (FWHM) is decreasing with increasing AlN layer thickness. Moreover, it is found that there is threshold value in rA at the temperature of 1400℃. As a result, rA value is observed 20.2 nm in AlN with growth temperature of 1650℃, this represents close to rA value (27.5 nm) in GaN.
Author(s): Shota Tsuda, Takumi Miyagawa, Reiya Aono, Atsushi Tomita, Tokushima Univ. (Japan); Hideki Hirayama, RIKEN (Japan); Yuusuke Takashima, Yoshiki Naoi, Kentaro Nagamatsu, Tokushima Univ. (Japan)
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We grew the AlN on c-plane sapphire substrate to investigate of effect in inversion domain formation by the temperature of buffer layer. As a result, the values of Full width at half maximum (FWHM) by X-ray rocking curve were decreasing with the difference temperature on the center of 800℃. Next, we grew the AlN several growth rates using 300℃ buffer layers to investigate thermal diffusion of oxygen from sapphire to AlN. The -c polarity AlN were grown in case of the low growth rate. As a result, FWHM obtained at tilt and twist diffractions were 210 and 350 arcsecond, respectively.
Author(s): Sae Katsuro, Weifang Lu, Meijo Univ. (Japan); Naoki Sone, Meijo Univ. (Japan), Koito Manufacturing Co., Ltd. (Japan); Kazuma Ito, Nanami Nakayama, Renji Okuda, Yoshiya Miyamoto, Yukimi Jinno, Shiori Yamamura, Motoaki Iwaya, Tetsuya Takeuchi, Satoshi Kamiyama, Meijo Univ. (Japan)
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GaInN/GaN multi-quantum shells nanowires (NWs) are coaxially grown in non-polar m-plane or semi-polar r-plane surface, which is expected to improve the luminous efficiency. The emission wavelengths usually redshift from the sidewall to top c-plane region. However, the emission from c-plane has low luminous efficiency. In this research, the c-plane area of NWs in one sample was removed by dry etching prior to the fabrication process, while the other one without c-plane etching was prepared to investigate the effect of c-plane region on the luminescence intensity. The sample with etching shows 12 times higher output power than the sample without etching.
Author(s): Yukimi Jinno, Renji Okuda, Meijo Univ. (Japan); Naoki Sone, Meijo Univ. (Japan), Koito Manufacturing Co., Ltd. (Japan); Weifang Lu, Yoshiya Miyamoto, Kazuma Ito, Shiori Yamamura, Sae Katsuro, Nanami Nakayama, Satoshi Kamiyama, Tetsuya Takeuchi, Motoaki Iwaya, Meijo Univ. (Japan)
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A nitride-based light-emitting structure composed of a GaN nanowire core and GaInN/GaN multi-quantum shells (MQSs) is promising for high performance optoelectronic devices. By growing high crystalline quality MQS on the nonpolar (m-plane) sidewall of the nanowires, an improvement of luminous efficiency is expected. For Mg activation in p-GaN under the tunnel junction is a big challenge, in this work, we carried out the sputtering growth of n-GaN capping layer on the tunnel junction/p-GaN/MQS/nanowire structures for the first time. Single crystalline n-GaN was successfully grown mainly on the tip of the nanostructures.
Author(s): Solumtochukwu F. Nwabunwanne, William R. Donaldson, Univ. of Rochester (United States)
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Aluminum gallium nitride (AlxGa1–xN) -based- metal-semiconductor-metal ultraviolet photodiodes were successfully designed and fabricated using conventional photolithography techniques and tested experimentally to study the spectral sensitivity across different Al content, x, with x varying from 0 to 0.3. (Al)GaN-based UV photodiodes (PD’s) have wide and tunable direct band gaps. The ability to easily select the photo detected wavelength by simply varying the aluminum content of GaN thin film (AlxGa1–xN ) is a significant advantage of these group III–V compounds. Typically, metal-semiconductor-metal PD’s grown on (Al)GaN thin films result in ultrafast photodetection because of their highly mobile carriers. These devices are limited by the carrier transit time due to the negligible capacitance presented by their interdigitated fingers.
Author(s): Selvy U. Hepriyadi, Mei-Yun Zhang, Jun-Wei Zhou, Pinghui S. Yeh, National Taiwan Univ. of Science and Technology (Taiwan)
Author(s): Tuba Sarwar, Pei-Cheng Ku, Univ. of Michigan (United States)
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We propose a concept of an optics-free optical spectrometer operational across visible to infrared spectral range. The design utilizes the InN/GaN dot-in-wire (DIW) nanostructures array as absorptive filters integrated with standard silicon photodiodes. The spectral response of each DIW nanostructure is controlled by local strain engineering. The insensitivity of the spectral responses to the incident angle of light is also shown.
Author(s): Philip Chan, Vincent Rienzi, Norleakvisoth Lim, Hsun-Ming Chang, Michael Gordon, Steven P. DenBaars, Shuji Nakamura, Univ. of California, Santa Barbara (United States)
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Highly relaxed InGaN buffer layers were grown by MOCVD across an entire 2-inch c-plane sapphire substrate. These buffer layers were relaxed by the thermal decomposition of a high composition InGaN underlayer. Due to a reduction in compositional pulling, quantum wells regrown on an InGaN buffer relaxed by this method showed a 75 nm redshift when compared to those on a co-loaded GaN template reference. This technique has enabled red devices with record high active region growth temperatures.
Author(s): Nathan A. Dvorak, Pei-Cheng Ku, Univ. of Michigan (United States)
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A tactile sensor ready for integration into robotic and prosthetic systems is proposed and demonstrated. Our sensor can determine the direction, force, and shape of a shear force with mN resolution. By monitoring how the sensor's emission evolves versus time for individual sensor nodes we can also map the location of applied forces. Our sensor utilizes a low-footprint and ultra-thin design to simulate measurement capabilities of human fingertips while retaining a simple-to-operate platform.
Author(s): Yun-Sheng Li, Ray-Hua Horng, Fu-Gow Tarntair, National Yang Ming Chiao Tung Univ. (Taiwan)
Author(s): Yu-Hsuan Hsu, Ray-Hua Horng, Yi-Hsin Lin, National Yang Ming Chiao Tung Univ. (Taiwan); Ming-Hsien Wu, Industrial Technology Research Institute (Taiwan)
Author(s): Zhe Zhuang, Daisuke Iida, Kazuhiro Ohkawa, King Abdullah Univ. of Science and Technology (Saudi Arabia)
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We investigated the performance of InGaN-based red and green micro LEDs ranging from 98 × 98 µm2 to 17 × 17 µm2. The 47 × 47 µm2 red and green micro-LEDs were obtained an on-wafer EQE of 0.36% at the peak wavelength of 626 nm at 4 A/cm2. The peak wavelength was close to the red primary color defined in the Rec. 2020 standard in CIE 1931. We also evaluated the temperature stability of the micro-LEDs. The characteristic temperature was obtained 50 and 411 K under 10 A/cm2 operation for the red and green LEDs, respectively.
Author(s): Xiaoli Liu, Muhammad Ishfaq, Chee-Keong Tan, Clarkson Univ. (United States)
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Electronic and structural properties of (Al1-xInx)2O3 alloys are investigated using first principles density functional theory calculations. Different phases of AlInO alloys were studied, which include the corundum, monoclinic and cubic phases. Structural properties such as lattice constant and equilibrium volume are investigated. Band structures of AlInO were analyzed to determine the energy band gap. Electronic band alignment between AlInO and AlInN is also investigated, implying the possibility of type-I band lineup of the heterojunction. Further details will be discussed in depth.
Author(s): Anna Szerling, Andrzej Taube, Maciej Kaminski, Lukasiewicz Research Network (Poland); Marek Ekielski, Lukasiewicz Research Network (Poland); Jarosław Tarenko, Karolina Pągowska, Lukasiewicz Research Network (Poland); Maciej Kozubal, Lukasiewicz Research Network (Poland); Kamil Kosiel, Lukasiewicz Research Network (Poland), Ctr. for Advanced Materials and Technologies, Warsaw Univ. of Technology (Poland); Renata Kruszka, Lukasiewicz Research Network (Poland); Krystyna Golaszewska-Malec, Lukasiewicz Research Network (Poland); Ernest Brzozowski, Lukasiewicz Research Network (Poland); Norbert Kwietniewski, Ryszard Kisiel, Warsaw Univ. of Technology (Poland)
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Normally-off AlGaN/GaN HEMTs with p-GaN-gate, which offer high drain current and low on-state resistance at high threshold voltage and breakdown voltage values above 600V, are particularly attractive for high-power electronics applications. In this work we present the results of development of high power normally-off p-GaN gate AlGaN/GaN high electron mobility transistors carried out at Łukasiewicz Research Network-Institute of Microelectronics and Photonics. We have developed key technological steps i.e. selective etching of p-GaN layers over AlGaN, deposition of proper passivation layer as well as thermally stable isolation of adjacent devices using selective Fe+ ion implantation, which were integrated in the process flow of manufacturing of high power transistors. Finally we have shown measurements of developed normally-off p-GaN gate AlGaN/GaN HEMT power transistors assembled using in-house developed process in TO-220 package.
Author(s): Tae Kyoung Kim, A. B. M. Hamidul Islam, Yu-Jung Cha, Joon Seop Kwak, Korea Institute of Energy Technology (Korea, Republic of)
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We have fabricated InGaN/GaN multiple-quantum-well flip-chip blue ultrathin side-emitting (USE) light-emitting diode (LED) by top and bottom mirrors and investigated the sidewall light emission performances for backlight unit. Fabricated USE-LED has uniform light-output-power (LOP) and peak wavelength characteristics at each sidewall except poor light extraction efficiency (LEE) which is improved by fabricating ZnO nanorods on each sidewall. The optimized nanorods improve the LEE of USE-LED. Thus, the LOP increases >80% compared to the Reference-LED. Furthermore, the light-tools simulation results reveal that the LEE of nanorods-based USE-LED increases in lateral direction due to decrease in internal reflection of light.
Session 12: (Red) LEDs and Micro LEDs
Session Chairs: Yasufumi Fujiwara, Osaka Univ. (Japan), Noelle Gogneau, Ctr. de Nanosciences et de Nanotechnologies (France)
Author(s): Lars Samuelson, Lund Univ. (Sweden)
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The large lattice mis-match between red-emitting active layers, with at least 35% indium in the QWs, and the GaN substrate still limits the efficiencies to very low values, typically <5%. We propose to use seeding techniques originally developed for nanowire growth, to seed the formation of ternary InGaN pyramids later converted into thin c-facet platelets of InGaN. The top-facet of each such template is on the scale 300nm to 1µm, thus better described as template for nanoLEDs. These can either be used as single nanoLED for a pixel or as an array of such nanoLEDs, constituting a complete microLED pixel.
Author(s): Kazuhiro Ohkawa, Daisuke Iida, Zhe Zhuang, King Abdullah Univ. of Science and Technology (Saudi Arabia)
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Fabrication of InGaN-based RGB micro-LEDs is crucial to realize inexpensive micro-LED displays. We have grown InGaN-based red LED structures on c-plane patterned sapphire substrates (PSS) by our original metalorganic vapor-phase epitaxy (MOVPE). The structures are p-GaN/hybrid MQWs/(InGaN/GaN) SLs/n-AlGaN/thick-n-GaN/GaN/PSS. The hybrid MQWs consist of red DQWs and blue SQW, resulting in intense red EL emissions. The thick-n-GaN can release compressive strain from substrates and reduce defect density. The overall structure was pseudomorphic. The device performance of the standard-size red LEDs and 17 m x 17 m micro-LEDs will be shown in the presentation.
Author(s): Hongxing Jiang, Jingyu Lin, Texas Tech Univ. (United States)
Author(s): Krzysztof Gibasiewicz, Agata Bojarska-Cieślińska, Grzegorz Muziol, Czeslaw Skierbiszewski, Institute of High Pressure Physics (Poland); Szymon Grzanka, Institute of High Pressure Physics (Poland), TopGaN Ltd. (Poland); Anna Kafar, Institute of High Pressure Physics (Poland); Piotr Perlin, Institute of High Pressure Physics (Poland), TopGaN Ltd. (Poland); Stephen Najda, TopGaN Ltd. (Poland); Tadeusz Suski, Institute of High Pressure Physics (Poland)
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In this paper, we try to resolve problems related to decreasing the size of an LED, and find a solution that would let us preserve optoelectronics parameters. The main idea is to use tunnel junctions to define the current path and, therefore, define the size of µLED. This way, during fabrication, there is no need to etch the active region. That way, it does not introduce any degradation nor problems related to surface states or differences in electrical fields inside the device. We have fabricated such devices with sizes ranging from 100 µm-5 µm. In the characterization of these devices, it became apparent that, both electrical and optical parameters, are fully scalable with size. Most importantly, we do not observe an increase in the non-radiative recombination coefficient even for the smallest device. In addition, we observe excellent thermal stability of their light emission characteristics.
Session 13: LED Efficiency
Session Chairs: Aurelien David, Google (United States), Rinat Yapparov, KTH Royal Institute of Technology (Sweden)
Author(s): Dong-Pyo Han, Motoaki Iwaya, Tetsuya Takeuchi, Satoshi Kamiyama, Isamu Akasaki, Meijo Univ. (Japan)
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This study aimed to understand and elucidate the factors limiting efficiency in GaInN-light-emitting diodes (LEDs) via carrier- and thermo-dynamics analysis. To this end, the WPE of LED was decoupled into its component elements, and then carrier- and thermo-dynamics analyses were conducted using efficiency elements. These analyses clearly demonstrated that the carrier behavior is dependent of the driving current, i.e., internal quantum efficiency and voltage efficiency are simultaneously degraded due to the carrier accumulation in the active region.
Author(s): Mitsuru Funato, Yoshinobu Matsuda, Yoichi Kawakami, Kyoto Univ. (Japan)
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InGaN-based three dimensional structures fabricated on (-1-12-2) through a regrowth technique are promising for highly efficient polychromatic emitters because the structures do not involve (0001) polar-plane facets. We experimentally demonstrate (1) fast radiative recombination in all the facet quantum wells, (2) structure and eventually emission color tunability through the control of mask geometry for the regrowth, and (3) LED operation with pastel and white color emission. These findings suggest promising features of our polar-plane-free faceted InGaN quantum wells as the next generation visible emitters.
Author(s): Yasufumi Fujiwara, Shuhei Ichikawa, Dolf Timmerman, Jun Tatebayashi, Osaka Univ. (Japan)
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Development of an efficient red LED based on GaN is pivotal to ultra-small-size, full-color, and high-resolution micro-LED displays. We invented a narrow-band red LED using Eu-doped GaN (GaN:Eu). We have boosted the output power by actively manipulating radiative recombination probability of the Eu emission, which can be achieved through control of their photon fields in micro- and nano-cavities. In this talk, drastic enhancement of Eu emission due to the Purcell effect is demonstrated in a microdisk (MD) cavity and a two-dimensional photonic crystal (2D-PhC) nanocavity using GaN:Eu.
Session 14: Nanostructured Devices
Session Chairs: Gwénolé Jacopin, Institut NÉEL (France), Jonas Lähnemann, Paul-Drude-Institut für Festkörperelektronik (Germany)
Author(s): Ray-Hua Horng, National Chiao Tung Univ. (Taiwan); Chun-Xin Ye, Po-Wei Chen, National Chung Hsing Univ. (Taiwan); Daisuke Iida, Kazuhiro Ohkawa, King Abdullah Univ. of Science and Technology (Saudi Arabia); Yuh-Renn Wu, National Taiwan Univ. (Taiwan); Dong-Sing Wuu, National Chi Nan Univ. (Taiwan), National Chung Hsing Univ. (Taiwan)
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InGaN-based light-emitting-diodes (LEDs) in different chip sizes from 100x100 to 10x10 µm2 have been realized by laser-based direct writing and maskless technology. In comparison with the conventional AlGaInP LEDs, the demands for AlGaInP micro-LEDs are more complicated owing to the increased sidewall defects. However, in the scaling process of the InGaN micro LEDs, the optoelectronic characteristics are much different from AlGaInP-based micro-LEDs. The emission wavelength of the 10×10 μm2 InGaN-based LED is shifted from 617.15 to 576.87 nm as the injection current is increased from 0.1 mA to 1 mA. The blue shift is obvious than the others micro-LED and can attribute to the band filling effect. Furthermore, the light emission color can be changed from red to blue-green by increase injection current. The results suggest that the InGaN-based LED have a great scaling potential and might be free of serious sidewall effect, suitable for high-resolution, full-color displays applications.
Author(s): Yoshio Honda, Nagoya Univ. (Japan)
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The three-dimensional structure of GaN is expected to have new device applications in MEMS and optical applications. In this study, we have fabricated GaN cantilevers. The structures were fabricated by MOVPE with insulating GaN layers between the n-GaN layers. The cantilever structure was fabricated by Photo-electrochemical etching etching using an InGaN sacrificial layer inserted between the sandwich structure and the substrate. The cantilever structure was monomorphic, and the resonance was confirmed by applying an AC voltage. The Young's modulus was calculated from the resonance frequency and compared with previously reported values.
Author(s): Noelle Gogneau, Ctr. de Nanosciences et de Nanotechnologies (France); Pascal Chrétien, Lab. Génie électrique et électronique de Paris (France); Tanbir Kaur Sodhi, Amaury Chevillard, Laurent Couraud, Laurent Travers, Jean-Christophe Harmand, Francois H. Julien, Maria Tchernycheva, Ctr. de Nanosciences et de Nanotechnologies (France); Frédéric Houzé, Lab. Génie électrique et électronique de Paris (France)
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GaN nanowires (NWs), due to their high piezoelectric properties, are considered as promising nanomaterials to develop high-efficient piezoelectric generators. To further improve the device performances and use them for real applications, it is essential to establish the relationship between the NW characteristics and their piezoelectric conversion properties. Based on an advanced nano-characterization tool, we quantify the electromechanical coupling coefficient of GaN NWs and highlight that this coefficient is affected by the formation of the Schottky nano-contact harvesting the piezo-generated energy, and is extremely sensitive to the surface charge effects, strongly pronounced in sub-100 nm wide GaN NWs.
Session 15: Electronic and Nanostructured Devices
Session Chairs: Vitaliy S. Avrutin, Virginia Commonwealth Univ. (United States), Kazuhiro Ohkawa, King Abdullah Univ. of Science and Technology (Saudi Arabia)
Author(s): Enrico Zanoni, Matteo Meneghini, Gaudenzio Meneghesso, Fabiana Rampazzo, Veronica Zhan Gao, Chandan Sharma, Francesca Chiocchetta, Univ. degli Studi di Padova (Italy); Giovanni Verzellesi, Alessandro Chini, Marcello Cioni, Nicolò Zagni, Univ. degli Studi di Modena e Reggio Emilia (Italy); Claudio Lanzieri, Alessio Pantellini, Marco Peroni, Luca Latessa, Leonardo S.p.A. (Italy); Carlo De Santi, Univ. degli Studi di Padova (Italy)
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This paper reports results concerning dynamic performance and reliability of Fe-doped and C-doped 0.15 and 0.25 um-gate AlGaN/GaN HEMTs. Experimental results are compared to 2D hydrodynamic simulations in order to validate hypotheses on failure mechanisms. Dominant failure mechanism of Fe-doped devices is trapping of hot-electrons at AlGaN/SiN interface on the gate-drain region. C-doping enhances dynamic effects and degradation: in off-state, hole emission from 0.9 eV CN traps induces RON increase; in semi-on and on-state VT positive shift results from hot-electron injection into the buffer region under the gate, while RON increase is a consequence of hot-electron trapping into surface traps.
Author(s): Juhyeon Kim, Mohammed Azzouz, Duncan Steel, Pei-Cheng Ku, Univ. of Michigan (United States)
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A large long-range Coulomb interaction between two laterally positioned GaN single-photon emitters is shown. Compared to III-As quantum dots, GaN quantum dots enable highly localized wavefunctions, exhibit a small dielectric constant and strong piezoelectricity. These unique properties lead to a strong bitrion binding energy to be achievable between two GaN quantum dots at a distance as large as 40nm, enabling an optically addressable spin gate to be realized and paving the way for a GaN spin-based quantum processor.
Author(s): Gwénolé Jacopin, Sylvain Finot, Institut NÉEL (France); Corentin Le Maoult, David Vaufrey, CEA-LETI (France); Etienne Gheeraert, Institut NÉEL (France)
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Due the reduced dimensions of micro-light-emitting diodes (μLEDs), non-radiative sidewall recombinations are becoming increasingly important and therefore it is necessary to quantify the impact of surface recombinations (SR). Here, we probe the influence of SR on the optical properties of InGaN/GaN μLEDs with a spatial resolution of 100 nm and a time resolution of 50 ps using spatially-resolved time-correlated cathodoluminescence spectroscopy. Variations in carrier lifetime near sidewalls enabled us to quantify the surface recombination velocity. By coupling this technique with a diffusion model, we demonstrate that the combination of KOH treatment and Al2O3 passivation drastically improves the efficiency of μLEDs
Author(s): Zhe Zhuang, Daisuke Iida, Martin Velazquez-Rizo, Kazuhiro Ohkawa, King Abdullah Univ. of Science and Technology (Saudi Arabia)
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We demonstrated amber InGaN-based micro LEDs (47 × 47 µm2) with 606 nm peak emission at 20 A/cm2. The amber LEDs were obtained the output power density of 2.26 mW/mm2 at 20 A/cm2 by on-wafer EL measurement. Also, the peak on-wafer EQE was obtained as 0.56%. The peak wavelength of the micro-LEDs exhibited a large blue-shift from 624 to 591 nm at 5 to 100 A/cm2. We evaluated the temperature stability of the micro-LEDs. It found that the characteristic temperature was gradually increased with current density increase because SRH non-radiative recombination could be suppressed at high current densities.
Conference Chair
Institute of Industrial Science, The Univ. of Tokyo (Japan)
Conference Chair
Virginia Commonwealth Univ. (United States)
Conference Chair
Technische Univ. Chemnitz (Germany)
Program Committee
Otto-von-Guericke-Univ. Magdeburg (Germany)
Program Committee
Institute of High Pressure Physics (Poland)
Program Committee
Raffaella Calarco
Paul-Drude-Institut für Festkörperelektronik (Germany)
Program Committee
National Sun Yat-Sen Univ. (Taiwan)
Program Committee
National Central Univ. (Taiwan)
Program Committee
Martin Feneberg
Otto-von-Guericke-Univ. Magdeburg (Germany)
Program Committee
Kyoto Univ. (Japan)
Program Committee
Lab. Charles Coulomb (France)
Program Committee
Ecole Polytechnique Fédérale de Lausanne (Switzerland)
Program Committee
Yale Univ. (United States)
Program Committee
RIKEN (Japan)
Program Committee
National Chiao Tung Univ. (Taiwan)
Program Committee
Chih-Fang Huang
National Tsing Hua Univ. (Taiwan)
Program Committee
Motoaki Iwaya
Meijo Univ. (Japan)
Program Committee
Technische Univ. Berlin (Germany)
Program Committee
Elison Matioli
Ecole Polytechnique Fédérale de Lausanne (Switzerland)
Program Committee
Nippon Mektron, Ltd. (Japan)
Program Committee
Mie Univ. (Japan)
Program Committee
CEA-DRF (France)
Program Committee
Ritsumeikan Univ. (Japan)
Program Committee
Virginia Commonwealth Univ. (United States)
Program Committee
Institute of High Pressure Physics (Poland)
Program Committee
Univ. of Florida (United States)
Program Committee
Tae-Yeon Seong
Korea Univ. (Korea, Republic of)
Program Committee
Peking Univ. (China)
Program Committee
Hanyang Univ. (Korea, Republic of)
Program Committee
Maria Tchernycheva
Ctr. de Nanosciences et de Nanotechnologies (France)
Program Committee
Akio Wakejima
Nagoya Institute of Technology (Japan)
Program Committee
National Taiwan Univ. (Taiwan)
Program Committee
Seoul National Univ. (Korea, Republic of)