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Green Photonics Presentations

Laser-assisted Manufacturing and Micro/Nano Fabrication
(ordered chronologically by start date and time)

Mid-IR laser source using hollow waveguide beam combining
Paper 9726-1

Author(s):  Ian F. Elder, Selex ES Ltd. (United Kingdom), et al.
Conference 9726: Solid State Lasers XXV: Technology and Devices
Session 1: Eyesafe and Mid-IR Lasers I
Date and Time: Monday, February 15, 2016, 8:00 AM

Hollow waveguide technology is a route to efficient beam combining of multiple laser sources in a compact footprint. It is a technology appropriate for combining free-space or fibre-coupled beams generated by semiconductor, fibre or solid-state laser sources. This paper will present results of a breadboard mid-IR system comprising four laser sources combined using a hollow waveguide optical circuit. Three of the sources are quantum cascade lasers (QCLs), a semiconductor laser technology providing direct generation of midwave IR output. The combined beams provide 4.2 W of near diffraction-limited output co-boresighted to better than 20 µrad.


High throughput laser scribing of Cu(In,Ga)Se2 thin-film solar cells
Paper 9735-3

Author(s):  Andreas Burn, Berner Fachhochschule Technik und Informatik (Switzerland), et al.
Conference 9735: Laser Applications in Microelectronic and Optoelectronic Manufacturing (LAMOM) XXI
Session 1: Lasers in Photovoltaics
Date and Time: Monday, February 15, 2016, 9:10 AM

Laser scribing for monolithic cell-to-cell interconnection is an enabler technology for cost-competitive production of Cu(In,Ga)Se2 thin-film solar modules. In the last years we optimized and validated different scribing processes and demonstrated 16.6 percent efficiency on a laser-patterned, grid-less 8 cell mini-module. We demonstrated low dead-zone interconnects of <70µm width and a high performance/high throughput P3 lift-off process. Highest module performances were realized with slow (<200mm/s) P2-scribing, involving direct ablation of CIGS using picosecond pulses. In the running FP7-APPOLO project we optimized P2 processes to overcome this limitation and reach process speeds in excess of 1m/s. Here we present results validation experiments.


Comparative study of broadband, narrowband, and multi-wavelength resonant pumping of Er:YAG lasers
Paper 9726-6

Author(s):  Haro Fritsche, DirectPhotonics Industries GmbH (Germany), et al.
Conference 9726: Solid State Lasers XXV: Technology and Devices
Session 1: Eyesafe and Mid-IR Lasers I
Date and Time: Monday, February 15, 2016, 9:40 AM

The multiplicity of narrow absorption lines of erbium ions in the spectral range from 1450 to 1560 nm is exploited for the development of a highly efficient Er:YAG laser emitting at 1645 nm. We present a comparative analysis on the performance of resonantly pumped Er:YAG lasers using different pumping schemes including both broadband and narrowband sources as well as different pump wavelengths. An absorption efficiency of up to 96% is achieved when pumping with narrow bandwidth sources. Furthermore, multi-wavelength pumping allows for both substantial power scaling and reduction of the laser threshold, thus providing a low power-consuming laser system.


Room-temperature continuous-wave operation of BeZnCdSe quantum-well green-to-yellow laser diodes with sub-10 mA threshold current
Paper 9767-11

Author(s):  Jijun Feng, Univ. of Shanghai for Science and Technology (China), et al.
Conference 9767: Novel In-Plane Semiconductor Lasers XV
Session 3: Blue/Green Emitters
Date and Time: Monday, February 15, 2016, 4:00 PM

Low threshold current ridge waveguide structure BeZnCdSe quantum-well laser diodes (LDs) have been realized, with etching away the top p-type BeMgZnSe/ZnSe:N short-period superlattice cladding layer. Room-temperature continuous-wave lasing can be achieved for three type green-to-yellow lasers at wavelength of 540, 563, and 567 nm, respectively, with the cavity formed by the high-reflection-coated cleaved waveguide facets. The present ridge waveguide type LDs can realize a sub-10-mA threshold current. The device performance can be significantly improved with much lower power consumption.


Ultrafast laser drilling of injector nozzles
Paper 9740-35

Author(s):  Eric P. Mottay, Amplitude Systèmes (France), et al.
Conference 9740: Frontiers in Ultrafast Optics: Biomedical, Scientific, and Industrial Applications XVI
Session 8: Ultrashort Pulse Laser Processing
Date and Time: Monday, February 15, 2016, 4:10 PM

Drilling fuel injector nozzles for automotive industry is one of the first identified industrial application for ultrafast lasers. Nozzle design and engineering is key to future increases in fuel efficiency. Ultrafast lasers micro-processing offers unique flexibility, such as the realization of deep (up to 1 mm) holes with arbitrary shape (zero-taper, inversed-taper…). It also faces technical and economic challenges, such as processing speed and backwall protection. We will review in this presentation the drilling of Gasoline Direct Injection (GDI) nozzles, as well as recent development in laser and beam delivery technologies.


Green microfabrication for flexible electronics by laser direct synthesis and pattering technology
Paper 9735-14

Author(s):  Ming-Tsang Lee, National Chung Hsing Univ. (Taiwan), et al.
Conference 9735: Laser Applications in Microelectronic and Optoelectronic Manufacturing (LAMOM) XXI
Session 4: Laser Direct Writing: Joint Session with Conferences 9735 and 9738
Date and Time: Monday, February 15, 2016, 5:10 PM


Ultrafast laser direct micro-/nano-fabrication: Towards 4D optical printing
Paper 9736-6

Author(s):  Mangirdas Malinauskas, Vilnius Univ. (Lithuania), et al.
Conference 9736: Laser-based Micro- and Nanoprocessing X
Session 2: Laser Nano-Structuring and Processing
Date and Time: Tuesday, February 16, 2016, 10:30 AM

Ultrafast laser based micro- and nano-processing technologies enable the most advanced material manufacturing options. It is proved in terms of spatial resolution, fabrication throughput, choice of materials, and 3D structuring capability. Femtosecond pulses empower precise determination of interaction mechanisms creating a potential to choose the type of material modification within a confined volume. Selectivity of femtosecond direct laser writing enables tuning of physical (mechanical stiffness, refractive index), chemical (reactivity), biological (biocompatibility, resorption) material properties. This can be employed for 4D optical printing, where besides the 3 coordinates in space, the material deposition (modification of its properties) can be distinctively controlled.


Cloaked contact fingers on solar cells enabled by 3D laser lithography
Paper 9738-5

Author(s):  Martin F. Schumann, Karlsruher Institut für Technologie (Germany), et al.
Conference 9738: Laser 3D Manufacturing III
Session 5: 3D Laser Structuring Devices and Lithography III: Joint Session with Conferences 9738 and 9759
Date and Time: Tuesday, February 16, 2016, 1:30 PM

Metallic contact fingers on the sun-facing side of solar cells are necessary to reduce Ohmic losses but also represent optically dead regions reducing the energy conversion per area. In this talk, we present two approaches to solve this problem by “cloaking the contacts”. The first approach uses graded-index metamaterials designed by two-dimensional Schwarz-Christoffel conformal maps, the second free-form surfaces designed by one-dimensional coordinate transformations. We provide proof-of-principle demonstrators using direct laser writing of polymer structures on silicon wafers with opaque metal contacts. Using the so-called shell-writing mode, fabrication times for “masters” are reduced significantly, potentially enabling mass fabrication via imprinting.


Electrically-driven 1D photonic crystal nanolaser integrated on silicon waveguides
Paper 9767-34

Author(s):  Guillaume Crosnier, Lab. de Photonique et de Nanostructures (France), et al.
Conference 9767: Novel In-Plane Semiconductor Lasers XV
Session 7: Lasers on Silicon
Date and Time: Tuesday, February 16, 2016, 5:10 PM

we demonstrate the first non-suspended electrically pumped hybrid InP on Silicon on Insulator (SOI) PhC nanolaser. Electrical injection is obtained using a rib-like structure (footprint below 100µm²) heterogeneously integrated on top of a SOI waveguide circuitry. Room temperature, continuous wave laser operation is shown at 1560nm with a threshold below 100µA. Unlike previous demonstrations, we greatly improve heat-sinking and stability thanks to the use of non-suspended structures.


Ultrashort pulse written volume-Bragg-gratings in fused silica for external stabilization of diode lasers with ultra-low spectral-drift
Paper 9730-19

Author(s):  Daniel Richter, Friedrich-Schiller-Univ. Jena (Germany), et al.
Conference 9730: Components and Packaging for Laser Systems II
Session 5: Laser Diode Packaging III
Date and Time: Wednesday, February 17, 2016, 9:20 AM

We report on our recent investigations on reducing the power dependent drift of externally stabilized laser diodes. Therefore, we directly inscribe VBGs in fused silica by applying ultrashort laser pulses and the phase mask scanning technique. The gratings are used to stabilize 969 nm laser diodes. While the inscribed VBGs are comparable to conventional ones with respect to grating geometries and reflectivities, they exhibit an extremely small residual drift of only 20 pm which is one order of magnitude improvement. We will present detailed information about the inscription process as well as the grating details and further possibilities for improvement.


Pulsed laser deposition of ultrasmall nanoparticles: Transformation into photosensitive black-TiO2 core-shell nanostructures
Paper 9737-21

Author(s):  David B. Geohegan, Oak Ridge National Lab. (United States), et al.
Conference 9737: Synthesis and Photonics of Nanoscale Materials XIII
Session 6: Laser-induced Nanostructures II: Joint Session with Conferences 9735 and 9737
Date and Time: Wednesday, February 17, 2016, 5:30 PM

The formation, pulsed laser deposition, and transformation of ultrasmall amorphous TiO2 nanoparticles into photosensitive core-shell TiO2/Ti2O3 crystalline nanoparticles (“black TiO2”) is reported. First, time-resolved in situ plume diagnostics are used to understand the conditions for the PLD of films consisting of pure, ultrasmall nanoparticles (UNPs, ~ 3 nm) by laser ablation and condensation in low-pressure background gases. Second, these ultrasmall, amorphous TiO2 nanoparticles are transformed by annealing into metastable crystalline phases such as “black TiO2”, a remarkable variant of TiO2 relevant to hydrogen production by photocatalytic water splitting, with preferred growth orientation linked to the defects and ordering of TiO6 octahedral units within each metastable amorphous nanoparticle, as determined by state-of-the-art electron microscopy and spectroscopy.


High-temperature monitoring of an oxy-fuel fluidized bed combustor using femtosecond infrared laser-written fiber Bragg gratings
Paper 9754-38

Author(s):  Robert B. Walker, National Research Council Canada (Canada), et al.
Conference 9754: Photonic Instrumentation Engineering III
Session PWed: Posters-Wednesday
Date and Time: Wednesday, February 17, 2016, 6:00 PM

Femtosecond Infrared (fs-IR) written fiber Bragg gratings (FBGs), have demonstrated great potential for extreme environment sensing. Harsh environments are inherent to the advanced power plant technologies under development to reduce greenhouse gas emissions. The performance of new power systems are currently limited by the lack of sensors and controls capable of withstanding the high temperature, pressure and corrosive conditions present. This paper discusses fabrication and deployment of several fs-IR written FBG arrays, for monitoring the temperature distribution within a fluidized bed combustor. Results include: calibration data to ~1100°C, discussion of deployment strategies, contrast with thermocouple data, and comments on reliability.


Laser-assisted reduction of graphene oxide for paper based large area flexible electronics
Paper 9736-35

Author(s):  Enkeleda Balliu, Mid Sweden Univ. (Sweden), et al.
Conference 9736: Laser-based Micro- and Nanoprocessing X
Session 8: Large Area Micro/Nano Structuring, Laser Interference Patterning
Date and Time: Thursday, February 18, 2016, 9:10 AM

In this work we present fabrication of conductive tracks on paper based substrates by laser assisted reduction of Graphene Oxide (GO). Printed electronics on paper based substrates is becoming more popular due to lower cost and recyclability. Fabrication of conductive tracks is of great importance where metal, carbon and polymer inks are commonly used. An emerging option is reduced graphene oxide (r-GO). Here we have evaluated different laser sources for reduction of GO, showing promising results with a reduction of sheet resistance from 3.5 MOhm for unreduced GO down to 550 Ohm without any observable damage to the paper substrate.


Repurposing mainstream CNC machine tools for laser-based additive manufacturing
Paper 9738-31

Author(s):  Jason B. Jones, Hybrid Manufacturing Technologies (United States), et al.
Conference 9738: Laser 3D Manufacturing III
Session 11: Applications, Systems, Process Developments for Additive Manufacturing I
Date and Time: Thursday, February 18, 2016, 2:20 PM

Despite its commercial success and unique technical capabilities, laser-based industrial 3D printing (additive manufacturing, AM) systems are not yet able to produce parts with the accuracy and surface finish of CNC machining. To enable the geometry and material freedoms afforded by AM, yet achieve the precision and productivity of CNC, hybrid combinations of these two processes have started to gain traction. The engineering to achieve combined processing has also led to a novel beam delivery approach that allows automated changeover between milling and laser-processing in mainstream CNC machines. This presentation highlights its development, challenges and future impact on laser processing.


Post-mortem characterization of fs laser-generated micro-pillars in Li(Ni1/3Mn1/3Co1/3)O2 electrodes by laser-induced breakdown spectroscopy
Paper 9736-47

Author(s):  Peter Smyrek, Karlsruhe Institute of Technology (Germany), et al.
Conference 9736: Laser-based Micro- and Nanoprocessing X
Session 11: Advanced Laser Structuring for Energy Storage and Conversion
Date and Time: Thursday, February 18, 2016, 4:20 PM

The development of new active materials, electrode architectures and innovative manufacturing strategies for lithium-ion batteries is quite important in order to optimize battery performance and production costs. Lithium nickel manganese cobalt oxide (NMC) has been reported as one of the promising cathode material because of its many advantages such as high rate capability. The lithium distribution in electrochemically cycled and unstructured / laser-structured NMC cathodes was investigated post-mortem by using Laser-Induced Breakdown Spectroscopy. The main goal is to develop an optimized three dimensional cell design with improved electrochemical properties based on studies of the homogeneity of the local State-of-Charge.


High speed, high quality Li-ion battery foil cutting using nanosecond lasers
Paper 9736-49

Author(s):  Jim M. Bovatsek, Spectra-Physics (United States), et al.
Conference 9736: Laser-based Micro- and Nanoprocessing X
Session 11: Advanced Laser Structuring for Energy Storage and Conversion
Date and Time: Thursday, February 18, 2016, 5:00 PM

.Pulsed infrared (IR) lasers have, in many cases, successfully replaced mechanical punching processes for Li-ion battery foil cutting. Past studies have shown that using green or ultraviolet (UV) lasers, smaller kerf width and better edge quality can be achieved. However, the cutting speed achieved was low and not acceptable to battery manufacturers. We present Li-ion battery foil cutting results achieved using high power nanosecond Quasar® hybrid fiber laser with pulse-shaping technology. The results show speeds of 1 m/s or higher can be achieved with a burr size of 10 um or less for cutting current-carrying conductors, anode, and cathode foils.


Renewable Energy Generation: Fusion and Photovoltaics
(ordered chronologically by start date and time)

Development of numerical modeling program for organic/inorganic hybrid solar cells by including tail/Interfacial states models
Paper 9743-7

Author(s):  Kuan-Ying Ho, National Taiwan Univ. (Taiwan), et al.
Conference 9743: Physics, Simulation, and Photonic Engineering of Photovoltaic Devices V
Session 2: Advances in Simulation of Photovoltaic Devices
Date and Time: Monday, February 15, 2016, 2:40 PM

A simulation software is developed for modeling the organic(PEDOT:PSS)/inorganic(Si) hybrid solar cells. The simulation software is based on solving the Poisson’s and drift-diffusion equation by utilizing the 1D/2D finite element method (FEM). A Gaussian distribution function or an exponential decay of tail states model is added to simulate the carrier transportation. Such Gaussian distributed tail states are placed around the LUMO and HOMO of the organic material and provide a path for carriers generated in the organic material to hop. Also, the function of field dependent mobility is developed and considered to better describe the carriers in the organic material. In this research, a planar hybrid solar cell is set up as the simulation model. To verify the software developed for simulating the organic / inorganic hybrid solar cells, experimental results are set as the reference for J-V curve fitting, where a good agreement is reached by the fitting experimental results.


Organic molecules for photo-isomeric storage
Paper 9745-7

Author(s):  Hal Gokturk, Ecoken (United States), et al.
Conference 9745: Organic Photonic Materials and Devices XVIII
Session 2: Solar Cells
Date and Time: Monday, February 15, 2016, 2:50 PM

Azobenzene and stilbene molecules which absorb light and store the photon energy as a change in molecular conformation are promising for harvesting of solar energy. In this research two modifications are proposed to improve the fraction of stored energy, which is less than 20%. In modification A, benzene rings are replaced by pyridine rings. In modification B, one of the hydrogens in each benzene ring is replaced by a chlorine atom. Analysis of the proposed molecules by quantum mechanical calculations indicate that stored energy values of B are 2.6 to 4 times higher than those of the original molecules.


Nanospectroscopy of PV devices
Paper 9743-8

Author(s):  Marina S. Leite, Univ. of Maryland, College Park (United States), et al.
Conference 9743: Physics, Simulation, and Photonic Engineering of Photovoltaic Devices V
Session 3: Advances in Characterization of Photovoltaic Devices
Date and Time: Monday, February 15, 2016, 3:30 PM

We resolve the Voc of photovoltaic devices with nanoscale spatial resolution by realizing a variant of Kelvin probe force microscopy, where the difference between the contact potential difference under illumination and in the dark is equal to the photo-generated voltage of the device. We combine this metrology with scanning photocurrent microscopy using near-field scanning microscopy (NSOM) probes as a local source of excitation to image local variations in Jsc within the material, also with nanoscale resolution. We spatially and spectrally resolve the external quantum efficiency within the solar cell devices, while mimicking the power density operation conditions of real devices.


Local transport properties investigation by correlating hyperspectral and confocal luminescence images
Paper 9743-11

Author(s):  Gilbert El-Hajje, Electricité de France (France), et al.
Conference 9743: Physics, Simulation, and Photonic Engineering of Photovoltaic Devices V
Session 3: Advances in Characterization of Photovoltaic Devices
Date and Time: Monday, February 15, 2016, 4:40 PM

The study presents a correlation between two imaging setups: The Hyperspectral Imager and the Scanning Confocal Microscope. These techniques are capable of measuring photovoltaic parameters such as maps of the bang gap energy, external quantum efficiency and the quasi-Fermi levels splitting. Nevertheless, when it comes to thin films materials, the origin of the spatial fluctuations of the latter remain unclear. Correlating these two techniques allows the investigation at the micron scale of the impact of transport properties on a given solar cell's PV performance. This correlation technique is demonstrated and applied on CIGS solar cells.


Silicon solar cell using optimized intermediate reflector layer
Paper 9743-18

Author(s):  Mohamed A. Swillam, The American Univ. in Cairo (Egypt), et al.
Conference 9743: Physics, Simulation, and Photonic Engineering of Photovoltaic Devices V
Session 4: Advances in Light Management and Spectral Shaping of Photovoltaic Devices
Date and Time: Tuesday, February 16, 2016, 9:20 AM

Thin film silicon based photovoltaic cells, have the advantages of using low cost nontoxic abundant constituents and low thermal manufacturing budget. However, better long-term efficiencies need to be achieved overcoming its inherent bad electrical properties of amorphous and/or microcrystalline Silicon. For the goal of achieving best results, multijunction cells of amorphous and microcrystalline silicon thin layers are industrially and lab utilized in addition to using one or more light management techniques such as textured layers, periodic and plasmonic back reflectors, flattened reflective substrates and intermediate reflector layer (IRL) between multijunction cells. The latter, IRL, which is the focus of this paper, serves as spectrally selective layer between different cells of the multijunction silicon thin film solar cell. IRL, reflects to the top cell short wavelength while permitting and scattering longer ones to achieve the best possible short circuit current. In this study a new optimized periodic design of Intermediate reflector layer in micromorph (two multijunction cells of Microcrystalline and Amorphous Silicon) thin film solar cells is proposed. The optically simulated short circuit current reaches record values for same thickness designs when using all-ZnO design and even better results is shown if Lacquer material is used in combination with ZnO. The design methodology used in the paper can be easily applied to different types of IRL materials and also extended to triple and the relatively newly proposed quadruple thin films solar cells.


Design and fabrication of a micro CPV system based on Cu(In,Ga)Se2 microcells array
Paper 9743-19

Author(s):  Sebastien Jutteau, Institut de Recherche et Développement sur l'Energie Photovoltaïque (France), et al.
Conference 9743: Physics, Simulation, and Photonic Engineering of Photovoltaic Devices V
Session 4: Advances in Light Management and Spectral Shaping of Photovoltaic Devices
Date and Time: Tuesday, February 16, 2016, 9:40 AM

Miniaturized cells are increasingly used in CPV systems. We propose a microconcentration systems adapted to thin film microcells arrays. Based on a numerical study to design the optical system with only plano-spherical microlenses and the development of a fabrication process using photolithography, we show a first, very compact, prototype coupling 2500 microcells and microlenses arrays for middle concentration applications.


Design and test of a new facility for assessing spectral normal emittance of solid materials at high temperature
Paper 9744-18

Author(s):  Luca Mercatelli, Istituto Nazionale di Ottica (Italy), et al.
Conference 9744: Optical Components and Materials XIII
Session 4: Optical Systems
Date and Time: Tuesday, February 16, 2016, 10:10 AM

The measurement of spectral emittance is a key topic in the study of new compositions, depositions and mechanical machining of materials for solar absorption and for renewable energies. In this work we report on the realization and testing of a new experimental facility for the measurement of directional spectral emittance which provides emittance spectral information in a controlled environment at medium-high temperatures up to 1300 K. In our device the first test were carried out comparing the results obtained for HfC and TaB2 ultra-refractory ceramic samples to previous monochromatic measurements performed in a research solar furnace, obtaining a good agreement. Moreover, a metallic sample with rare-earth deposition was tested


Charge-carrier dynamics in perovskite semiconductors and the significance for solar cells and lasers
Paper 9746-21

Author(s):  Michael B. Johnston, Univ. of Oxford (United Kingdom), et al.
Conference 9746: Ultrafast Phenomena and Nanophotonics XX
Session 5: Ultrafast Phenomena in Perovskites
Date and Time: Tuesday, February 16, 2016, 10:30 AM

Perovskite semiconductors are a new class of solar cell material that have emerged recently. Remarkable advances have occurred over the past 3 years with power conversion efficiencies for perovskite solar cells leaping from under 10% in 2012 to exceed 20% this year. To unleash the full potential of these materials it is important to gain a firm understanding of their charge carrier dynamics. Here we use time resolved terahertz conductivity spectroscopy to uncover charge generation and recombination dynamics in a range of perovskites. This work has direct implications for the development of perovskite solar cells and lasers.


Design optimization of thin-film/wafer-based tandem junction solar cells using analytical modeling
Paper 9743-22

Author(s):  Lauren M. Davidson, The Univ. of Iowa (United States), et al.
Conference 9743: Physics, Simulation, and Photonic Engineering of Photovoltaic Devices V
Session 5: Perovskites and Hybrid Photovoltaic Devices
Date and Time: Tuesday, February 16, 2016, 11:20 AM

In PC1D and SCAPS solar cell modeling, convergence errors occur if a tandem cell based on a thin-film absorber and a wafer-based absorber is modeled. We have developed an analytical model, designed using Matlab, to model single junction and tandem junction solar cells. In our model we can parametrize various solar cell inputs to optimize quantum efficiency and current-voltage-power characteristics. The Matlab program allows for modeling of both n-terminal and series tandem cells. This paper will present data on design optimization of a perovskite/Si tandem junction solar cell to achieve >30% cell efficiency using the analytical model.


Performance impact of luminescent coupling on monolithic 3- to 6-volt phototransducers for photonic power systems
Paper 9743-30

Author(s):  Matthew M. Wilkins, Univ. of Ottawa (Canada), et al.
Conference 9743: Physics, Simulation, and Photonic Engineering of Photovoltaic Devices V
Session 7: Advances in III-V Photovoltaic Materials and Devices
Date and Time: Tuesday, February 16, 2016, 4:20 PM

A five-junction, monolithically integrated GaAs phototransducer device with > 61% power conversion efficiency and > 5 V open-circuit voltage under monochromatic illumination is presented. Drift-diffusion based simulations including a luminescent coupled generation term are used to study photon recycling and luminescent coupling between each junction. Using the full width of the quantum efficiency at 90% of its maximum as a metric, spectral response of this device is broadened by a factor of 3.5 when luminescent coupling is included in the simulation. This broadened response is consistent with experimental measurements. Photon recycling is also found to significantly improve the voltage of all junctions.


Thin-film vapor-liquid-solid growth of InP for III-V photovoltaics
Paper 9743-31

Author(s):  Christopher G. Bailey, Old Dominion Univ. (United States), et al.
Conference 9743: Physics, Simulation, and Photonic Engineering of Photovoltaic Devices V
Session 7: Advances in III-V Photovoltaic Materials and Devices
Date and Time: Tuesday, February 16, 2016, 4:40 PM

In this investigation, polycrystalline InP material has been produced using a thin film (TF) adaptation of the vapor-liquid-solid (VLS) crystal growth method abbreviated TF-VLS. Electron dispersive spectroscopy of this material indicates the presence of both In and P. Preliminary photoluminescence measurements show emission of 1.34 eV indicative of the InP bandgap. Powder x-ray diffraction measurements have been made resulting in known InP peaks. In addition, drift-diffusion-based photovoltaic simulation software will be used to investigate the effects on performance of various electronic materials properties typical of polycrystalline materials.


Modeling of effects of using polycrystalline substrates for low-cost III-V photovoltaics
Paper 9743-33

Author(s):  Zachary S. Bittner, Rochester Institute of Technology (United States), et al.
Conference 9743: Physics, Simulation, and Photonic Engineering of Photovoltaic Devices V
Session 7: Advances in III-V Photovoltaic Materials and Devices
Date and Time: Tuesday, February 16, 2016, 5:20 PM

High-efficiency III-V photovoltaics depends on high-quality crystalline Germanium substrates as epitaxy templates, which leads to high cell cost. Recrystallized thin-film substrates can reduce costs, but the effects of polycrystallinity and surface roughness on material quality are not quantitatively understood. (In)GaAs solar cells will be grown on crystalline (001) and polycrystalline GaAs and Ge substrates in order to model the impacts of APDs, grain size, and orientation on epitaxial material quality. Models accounting for grain size effects will be developed as predictive tools for using recrystallized “virtual” substrates to predict cell efficiency across many grain sizes and surface morphologies.


1.7eV AlGaAs solar cells epitaxially grown on silicon by SSMBE using a superlattice and dislocation filters
Paper 9743-34

Author(s):  Arthur L. Onno, Univ. College London (United Kingdom), et al.
Conference 9743: Physics, Simulation, and Photonic Engineering of Photovoltaic Devices V
Session 7: Advances in III-V Photovoltaic Materials and Devices
Date and Time: Tuesday, February 16, 2016, 5:40 PM

1.7eV Al0.2Ga0.8As solar cells have been epitaxially grown on Si and GaAs by SSMBE. For the samples grown on Si, an AlGaAs/GaAs superlattice followed by dislocation filters was used to reduce the TDD to about 10^7cm-2. The best cells exhibit a Voc of 964mV on Si and 1128mV on GaAs with high fill factors of respectively 77.6% and 80.3%. Due to the lack of an anti-reflection coating, relatively low Jsc have been measured: 7.30mA.cm-2 on Si and 6.64mA.cm-2 on GaAs. Best efficiencies were respectively 5.46% and 6.02%. A comprehensive model, taking into account the impact of threading dislocations, has also been developed.


Power conversion with Gallium Nitride devices
Paper 9748-35

Author(s):  Srabanti Chowdhury, Arizona State Univ. (United States), et al.
Conference 9748: Gallium Nitride Materials and Devices XI
Session 8: Electron Devices
Date and Time: Wednesday, February 17, 2016, 9:00 AM

Recent studies in power conversion indicate that power converters designed with high efficiency GaN switches result in superior system performances, reducing losses at all levels and potentially leading to lower cost. Enabled by the growth of GaN on Si and availability of bulk GaN substrates, lateral and vertical geometry devices are perfectly positioned to address a large spectrum of power electronic application with increased power density. 600V lateral HEMTs can switch 1.5 times higher operating currents and at least 10 times faster than the state-of-the art Si-based devices without compromising the efficiency of the converter. This allows designing the full converter to operate at high frequencies, reducing the size of the passive components, thereby reducing the form-factor. The ability to operate at higher temperature allows smaller heat sinks making the converter compact. Vertical GaN device offers very high power density making it a more economic solution for higher power ranges.


High performance 1 eV dilute nitride solar cells using quantum wells with cascaded thermally-assisted resonant tunneling design
Paper 9743-38

Author(s):  Alexandre Freundlich, Univ. of Houston (United States), et al.
Conference 9743: Physics, Simulation, and Photonic Engineering of Photovoltaic Devices V
Session 8: Advances in Quantum Well and Superlattice-Enhanced Photovoltaic Devices
Date and Time: Wednesday, February 17, 2016, 9:10 AM

Here we report the demonstration of ~1 eV solar cells with open circuit voltages that exceed significantly the prior art (by nearly 10%). To make this breakthrough possible we have designed devices that incorporate sets of carefully crafted ultra-thin resonantly coupled multi-quantum wells of dilute nitrides. Devices fabricated with appropriate carrier extraction design exhibit near ideal carrier collection efficiency (QE ~1) and an open circuit voltage that approaches the radiative limit of Eg-0.4eV.


Effective drift mobility approximation in multiple quantum-well solar cells
Paper 9743-39

Author(s):  Kasidit Toprasertpong, The Univ. of Tokyo (Japan), et al.
Conference 9743: Physics, Simulation, and Photonic Engineering of Photovoltaic Devices V
Session 8: Advances in Quantum Well and Superlattice-Enhanced Photovoltaic Devices
Date and Time: Wednesday, February 17, 2016, 9:30 AM

We investigate a model for the photocurrent characteristics of multiple quantum well (MQW) solar cells using a carrier time-of-flight technique. The carrier averaged drift velocity in MQWs is found to have linear dependence on the internal field, similarly to carriers in bulk materials. This allows us to approximate MQWs as quasi-bulk materials having effective drift mobilities and simulate the characteristics of MQW cells by using the conventional drift-diffusion model. We have confirmed the model with experimentally obtained carrier collection efficiency, which agrees well when the carrier lifetime in the simulation is set to be tens to hundreds of nanoseconds.


Quasi-Fermi level splitting evaluation based on electroluminescence analysis in multiple quantum-well solar cells for investigating cell performance under concentrated light
Paper 9743-40

Author(s):  Tomoyuki Inoue, The Univ. of Tokyo (Japan), et al.
Conference 9743: Physics, Simulation, and Photonic Engineering of Photovoltaic Devices V
Session 8: Advances in Quantum Well and Superlattice-Enhanced Photovoltaic Devices
Date and Time: Wednesday, February 17, 2016, 9:50 AM

Under high-concentration sunlight condition, enhancement of open-circuit voltage (Voc) with increasing concentration ratio in thin-barrier multiple quantum wells (MQWs) solar cells has been reported to be faster than that in GaAs bulk cells. Investigation of this mechanism, the quasi-Fermi level splitting and the external luminescence efficiency were evaluated by analyzing electroluminescence spectra from a cell with reduced artifacts by temperature increase. It was suggested that the carrier localization inside MQWs results in smaller differences between EL peak energy and quasi-Fermi level splitting and radiative recombination can be dominant by carrier confinement, which may induce relatively higher Voc.


Design optimization for two-step photon absorption in quantum dots by infrared photocurrent spectroscopy
Paper 9743-42

Author(s):  Ryo Tamaki, RCAST, The Univ. of Tokyo (Japan), et al.
Conference 9743: Physics, Simulation, and Photonic Engineering of Photovoltaic Devices V
Session 9: Intermediate Band Solar Cells
Date and Time: Wednesday, February 17, 2016, 11:10 AM

Multi-stacked quantum dot solar cell (QDSC) is a promising candidate for intermediate band solar cell, which can exceed the Shockley-Queisser limit of single-junction solar cells. In currently reported QDSCs, however, photocurrent gain via two-step photon absorption degrades at room temperature due to thermal carrier escape from QDs. In this study, infrared photocurrent spectra in In(Ga)As QDSCs with different barrier materials are investigated by using Fourier-transform infrared spectroscopy technique at low temperature. A universal linear relationship between the threshold temperature and the absorption edge of infrared photo-response reveals strategy for cell optimization to achieve efficient two-step photon absorption at ambient conditions.


Self-formation of ultrahigh-density InAs quantum dots for intermediate-band solar cell applications
Paper 9743-44

Author(s):  Koichi Yamaguchi, The Univ. of Electro-Communications (Japan), et al.
Conference 9743: Physics, Simulation, and Photonic Engineering of Photovoltaic Devices V
Session 9: Intermediate Band Solar Cells
Date and Time: Wednesday, February 17, 2016, 11:50 AM

In-plane ultrahigh-density InAs quantum dots (QDs) were grown on an InAsSb wetting layer/GaAs(001) by molecular beam epitaxy. Coalescence and ripening phenomena of neighboring InAs QDs were effectively suppressed, and those ultrahigh-density QDs were embedded into a GaAsSb capping layer to form a type-II band structure. As a result, in-plane ultrahigh-density of 1×1012 cm-2 and a long photoluminescence decay time of 5 ns were obtained. The proposed growth method of ultrahigh-density InAs QDs is a promising way for development of intermediate-band solar cells with high power conversion efficiency.


Titanium oxide: electron-selective layers for contact passivation of thin-film crystalline silicon solar cells
Paper 9749-46

Author(s):  Yi Liu, Peking Univ. (China), et al.
Conference 9749: Oxide-based Materials and Devices VII
Session 9: Photovoltaics II
Date and Time: Wednesday, February 17, 2016, 2:25 PM

Passivated contacts with carrier-selective layers are important to highly efficient c-Si thin-film solar cells, as they can significantly reduce the minority carrier recombination and improve the majority carrier transport. In this work, we report the use of atomic-layer-deposited (ALD) TiOx thin films as electron-selective layers, forming metal-insulator-semiconductor (MIS) type contacts. The carrier-selection effect was demonstrated on intrinsic, n-type and n+-type silicon surfaces, considering contact recombination current J0c and contact resistivity Rc. The reduced J0c indicated a possible higher open-circuit voltage for devices, and the low resistivity exhibited improved conductivity. The effect of rapid-thermal-anneal (RTA) on contact performance was also investigated.


Exciton-dominated fast recombination in low-temperature CH3NH3PbClxI1-x perovskite thin films
Paper 9745-43

Author(s):  Som Sarang, Univ. of California, Merced (United States), et al.
Conference 9745: Organic Photonic Materials and Devices XVIII
Session 11: Organic/Inorganic Hybrids II
Date and Time: Wednesday, February 17, 2016, 4:50 PM


Simulation study of GaAsP/Si tandem cells including the impact of threading dislocations on the luminescent coupling between the cells
Paper 9743-45

Author(s):  Arthur L. Onno, Univ. College London (United Kingdom), et al.
Conference 9743: Physics, Simulation, and Photonic Engineering of Photovoltaic Devices V
Session 10: Photovoltaics Modeling: Joint Session with Conferences 9742 and 9743
Date and Time: Wednesday, February 17, 2016, 4:50 PM

A model, derived from the Shockley-Queisser detailed balance model, has been adapted to monolithically grown GaAsP/Si tandem cells. The model takes into account the impact of TDs as well as two surface geometries: flat and ideally textured. Additionally the luminescent coupling between the cells, due to reemitted photons from the top cell cascading to the bottom cell, has been considered. We show that, as the TDD increases, non-radiative recombinations take over radiative recombinations in the top cell and the luminescent coupling is quenched. As a result, high TDD cells need to be current-matched for optimal performances as the flexibility due to luminescent coupling is lost.


Down-conversion of solar photons using alkali vapors
Paper 9743-46

Author(s):  Hal Gokturk, Ecoken (United States), et al.
Conference 9743: Physics, Simulation, and Photonic Engineering of Photovoltaic Devices V
Session PWed: Posters-Wednesday
Date and Time: Wednesday, February 17, 2016, 6:00 PM

Alkali elements are known for their multi-photon emissions from excited states. Optical spectra of lithium to cesium were analyzed for down conversion of high energy photons of the solar spectrum to increase the efficiency of silicon solar cells. The spectra suggest that cesium is the most suitable for the down conversion. Cs absorbs at 456 nm & 459 nm. Primary emissions are at 852 nm & 894 nm and secondary emissions are at 917 nm & 876 nm. Cs melts at 28°C, therefore it can be vaporized with the heat generated by the sunlight and the solar cell.


Metal/metal-oxide nanocoatings on black silicon nano-grass for enhanced solar absorption and photochemical activity
Paper 9743-51

Author(s):  Pabitra Dahal, Masdar Institute of Science & Technology (United Arab Emirates), et al.
Conference 9743: Physics, Simulation, and Photonic Engineering of Photovoltaic Devices V
Session PWed: Posters-Wednesday
Date and Time: Wednesday, February 17, 2016, 6:00 PM

In this work we present our experimental results on the optical absorption enhancement of metal/metal-oxides nanocoatings on black silicon fabricated by reactive ion etch, atomic layer deposition and magnetron sputtering. Our results are compared to finite-difference time domain simulations based on the actual fabricated structures, as obtained by focused ion beam milling slice&view and TEM sample preparation. A study of the influence of various process parameters on the geometry of the fabricated micro and nanostructures and the corresponding change in optical properties is also presented. Applications of such highly absorbing metamaterials to full solar photocatalysis is discussed.


Green solar cells using natural pigments having complementary absorption spectrum
Paper 9743-55

Author(s):  Sreeja S., C.S.I.R. Madras Complex (India), et al.
Conference 9743: Physics, Simulation, and Photonic Engineering of Photovoltaic Devices V
Session PWed: Posters-Wednesday
Date and Time: Wednesday, February 17, 2016, 6:00 PM

Natural photosensitizers are non-toxic, inexpensive, biodegradable alternatives to the typically used metal-based porphyrins in Dye Sensitized Solar Cells. However, their narrow absorption spectra result in low efficiencies of the solar cells. In this study, we investigated co-sensitization of complementary natural plant pigments: chlorophyll, having an absorption maxima at 435 nm and 668 nm was used in combination with betanin, having an absorption maxima at 537nm. Results show that the broad absorption spectrum, attributed to co-sensitization of betanin with chlorophyll resulted in higher efficiency of 3.24% for the co-sensitized solar cells than efficiencies of 1.79% and 0.96% achieved for betanin and chlorophyll solar cells respectively.


Low-temperature and UV-irradiation treatments of porous titania-capped silica GNRs for dye solar cells (DSCs)
Paper 9749-43

Author(s):  Sarah Lai, Consiglio Nazionale delle Ricerche (Italy), et al.
Conference 9749: Oxide-based Materials and Devices VII
Session PWed: Posters-Wednesday
Date and Time: Wednesday, February 17, 2016, 6:00 PM

For DSCs some stringent requirements are needed such as transparency in the 500-600-nm. Moreover they need the use of a co-sensitizing NIR dye to improve absorbance in visible region. The use of GNRs with appropriate aspect ratio improves the organic dye adsorption. Here a nanostructured material, made of a core of gold nanorods incapsulated into a silica shell and finally coated with titania, were prepared and printed on a glass substrate. Before and after sintering procedure, films and nanoparticles were characterized morphologically and optically. Preliminary results showed a good retain of nanorods shape and optical properties and a promising efficiency.


Visible to near-infrared narrow-band thermal emitters based on silicon-rod photonic crystals
Paper 9756-53

Author(s):  Masahiro Suemitsu, Osaka Gas Co., Ltd. (Japan), et al.
Conference 9756: Photonic and Phononic Properties of Engineered Nanostructures VI
Session 12: Photonic Crystal Structures I
Date and Time: Thursday, February 18, 2016, 8:50 AM

Selective thermal emitters which can emit light at the wavelengths less than near-infrared regime are important for highly efficient thermo-photovoltaic (TPV) power generation systems. Here we demonstrate for the first time visible to near-infrared narrow-band thermal emission by using rod-type two-dimensional silicon photonic crystals. Maximum emissivity of 0.8 has been achieved at the wavelengths less than 1.1 um at 1300K, while the emissivity at the wavelengths of 1.1 and 4 um has been suppressed substantially below 0.05.


High-contrast subwavelength grating-based smart power window
Paper 9757-29

Author(s):  Ameen Elikkottil, Academy of Scientific & Innovative Research (India), et al.
Conference 9757: High Contrast Metastructures V
Session 8: Novel Devices
Date and Time: Thursday, February 18, 2016, 4:00 PM

High contrast subwavelength gratings based smart power window comprises of a high index TiO2 grating material on a planar glass substrate capable of simultaneous energy harvesting from IR radiation, heat load reduction and maximizing natural lighting. The proposed Smart Power Window (SPW) is simulated and optimized using rigorous coupled wave analysis and finite difference time domain methods to guide near infrared radiation (700-1100 nm) falling on the window to the edges, where silicon solar cells are placed for electricity generation. Simulations show that 20-30 W/m2 of electricity can be potentially generated using the SPW while simultaneously reducing the total infrared transmission by 30%, thereby reducing the heat load of buildings. SPW with a large area (>100 cm2) is fabricated using interference lithography.


Environmental Monitoring and Sensing
(ordered chronologically by start date and time)

Novel label-free biosensing technology for monitoring of aqueous solutions
Paper 9725-23

Author(s):  Florian Kehl, ETH Zürich (Switzerland), et al.
Conference 9725: Frontiers in Biological Detection: From Nanosensors to Systems
Session 6: New Biosensing Methods
Date and Time: Monday, February 15, 2016, 5:00 PM

Waste water, drinking water and other industrial water are increasingly polluted with a large variety of contaminants, such as pesticides or residuals of pharmaceuticals. In order to meet the demand for continuous and consistent monitoring of these aqueous solutions we propose a novel label-free technology comprising proprietary chip and reader device designs. The core of the system is constituted by a planar-grated-waveguide chip, dedicated to label-free sensing. The reader device operating with a novel read-out concept has proved to be highly sensitive towards effective refractive index changes and has enabled affinity studies for small and large molecules.


Interband cascade laser sources in the mid-infrared for green photonics
Paper 9767-37

Author(s):  Johannes Koeth, nanoplus GmbH (Germany), et al.
Conference 9767: Novel In-Plane Semiconductor Lasers XV
Session 8: Interband and Quantum Cascade Lasers
Date and Time: Wednesday, February 17, 2016, 8:50 AM

Tunable Laser Absorption Spectroscopy has proven to be a versatile tool for gas sensing applications. Especially the Mid-Infrared (MIR) wavelength region from 3 to 6 microns is of great interest since here many technologically relevant gas species as well as pollutants have fundamental absorption features. In recent years, interband cascade lasers (ICLs) have evolved into important laser sources for sensing since they are able to cover the MIR wavelength range of interest. In this work novel application-grade single-mode ICL devices with wavelength tuning ranges up to 30 nm suitable for addressing the air pollutant sulfur dioxide SO2 are presented.


Fully solution-processed organic light-emitting electrochemical cells (OLEC) with inkjet-printed micro-lenses for disposable lab-on-chip applications at ambient conditions
Paper 9745-30

Author(s):  Zhe Shu, Fraunhofer-Institut für Angewandte Optik und Feinmechanik (Germany), et al.
Conference 9745: Organic Photonic Materials and Devices XVIII
Session 8: OLEDs
Date and Time: Wednesday, February 17, 2016, 9:00 AM

Microfluidic lab-on-a-chip devices can be used for chemical/biological analyses such as environmental monitoring. However, in order to make a monolithic and cost-efficient/disposable sensing device, direct integration of excitation light source for fluorescent sensing is often required. Hereby we introduce an fully solution processed blue organic light-emitting electrochemical cells fabricated under ambient conditions. It is able to achieve light intensity > 2500 cd/m2 under pulsed driving mode and maintain stable after 1000 cycles, which fulfils requirements for simple fluorescent on-chip sensing applications. In order to further improve emitting light intensity, micro-lenses are inkjet printed on rear side of substrates.


Theoretical analysis of quantum-dot quantum cascade lasers: design considerations and current requirements
Paper 9767-50

Author(s):  Stephan Michael, Technische Univ. Kaiserslautern (Germany), et al.
Conference 9767: Novel In-Plane Semiconductor Lasers XV
Session 11: New Device Concepts
Date and Time: Wednesday, February 17, 2016, 4:20 PM

The present contribution investigates a microscopic model for electrically pumped quantum dots as active material for quantum cascade lasers. We consider an AlGaAs heterostructure composed of self-organized dots-in-a-well sandwiched between a source and a drain quantum wells. By computing the achievable steady-state gain including electron-electron and electron-phonon scattering processes, we obtain design requirements for the whole structure. Using an optimized "theoretical design," we predict that the quantum-dot active material can achieve similar modal gain with smaller threshold currents, compared to a standard quantum-well active material as used in quantum cascade lasers.


Climate engineering with oxide photocatalysts
Paper 9749-54

Author(s):  Hal Gokturk, Ecoken (United States), et al.
Conference 9749: Oxide-based Materials and Devices VII
Session 10: Oxides as Environmental Catalysts and Sensors
Date and Time: Wednesday, February 17, 2016, 4:20 PM

Photocatalysts which are activated by sunlight are promising materials to design climate engineering processes such as neutralization of pollutants in the atmosphere or creation of cloud condensation nuclei. In this research sequestration of CO2 in air with titanium oxide is investigated. Two types of interactions are of interest: (a) CO2 versus the photocatalytic surface, (b) CO2 versus reactive gas species (O2-, OH, OH-) generated by the photocatalyst. The analysis is carried out with quantum mechanical calculations. Results indicate that CO2 does not react with the TiO2 surface, but it can be sequestered with negative ions generated by the photocatalyst.


Impact of glycerol on zinc-oxide-based thin film transistors with indium molybdenum oxide transparent electrodes
Paper 9749-56

Author(s):  Mateusz T. Madzik, Masdar Institute of Science & Technology (United Arab Emirates), et al.
Conference 9749: Oxide-based Materials and Devices VII
Session 10: Oxides as Environmental Catalysts and Sensors
Date and Time: Wednesday, February 17, 2016, 4:50 PM

We report the fabrication of thin film transistors with ZnO channel and indium molybdenum oxide electrodes by sputtering. The fabricated transistors were then exposed to glycerol. We observe a permanent change in device performance after immersion of the FET in glycerol. Control structures without channel material are also used for demonstrating that the effect of saturation current increase is not due to glycerol alone as sugar alcohol is a low conductive medium. Various electrical and optical parameters are compared to pre-soak in ethanol control structures. The presented results are useful for further integration of photonics and electronics in sensing applications.


Low-cost flexible thin-film sensor devices from bacteria-synthesized nanoparticles
Paper 9749-57

Author(s):  Christopher Jacobs, Oak Ridge National Lab. (United States), et al.
Conference 9749: Oxide-based Materials and Devices VII
Session 10: Oxides as Environmental Catalysts and Sensors
Date and Time: Wednesday, February 17, 2016, 5:05 PM

We report here on the development of flexible thin-film sensors produced using low-cost starting nanomaterials, and low-temperature deposition and sensing to reducing the overall energy cost of production. Nanoparticle starting materials were synthesized by anaerobic metal-reducing bacteria, and pulsed laser was used to deposit flexible ZnO and ZnS thin-film sensors on polymeric substrates at temperatures of 150 °C. These sensors were found to be sensitive to UV-light, oxygen, and humidity and UV irradiation further improved sensitivity and reversibility. Statistical analysis described different chemical sensing mechanisms under dark and irradiated conditions, and also suggests that water and oxygen have different, mixed-sensing mechanisms under UV-irradiated conditions.


Oxide nano-ions for carbon dioxide sequestration
Paper 9749-64

Author(s):  Hal Gokturk, Ecoken (United States), et al.
Conference 9749: Oxide-based Materials and Devices VII
Session PWed: Posters-Wednesday
Date and Time: Wednesday, February 17, 2016, 6:00 PM

Conversion of carbon dioxide to a beneficial product which has economic value is the most viable solution to combat global warming. One such approach is mineralization of CO2 to carbonates by reacting it with water vapor. However the reaction does not proceed rapidly due to an activation barrier. What is proposed in this research is lowering of the barrier by adding oxide nanoions SO4, PO4 and SiO4 carrying a charge of -2 to -4. Quantum mechanical calculations indicate that the barrier is lowered to zero in the presence of the nanoions and the reactions yield H2CO3, HCO3- and CO3--.


Effects of UV activation on sorption/desorption kinetics and electronic response of carbon allotropes in humid and oxygen rich environments
Paper 9745-54

Author(s):  Eric Muckley, Oak Ridge National Lab. (United States), et al.
Conference 9745: Organic Photonic Materials and Devices XVIII
Session PWed: Posters-Wednesday
Date and Time: Wednesday, February 17, 2016, 6:00 PM

Demand is growing for carbon-based electronics because of their low cost, mechanical flexibility, and compatibility with roll-to-roll processing. Carbon allotropes including metallic and semiconducting carbon nanotubes, fullerenes, and graphene have shown promise for application in a wide range of flexible thin film electronic devices including photovoltaics, LEDs, transistors, biointerfaces, and sensors. While semiconducting carbon allotropes exhibit a wide range of bandgaps, intrinsic and extrinsic dopants allow for further tunability of the bandgap and work function of these materials. However, the environmental stability of doped films in oxygen and humid atmospheres may become a fundamental limitation on the practical application of carbon allotropes for optoelectronic and biomedical applications. The high surface area of carbon-based nanostructured materials allows gas adsorption which makes tuning of the optoelectronic properties of carbon allotropes unpredictable. An effective and popular method of inducing gas desorption from carbon surfaces is UV treatment. Here, we study the effect of UV activation on the electronic properties and sorption kinetics of different carbon nanostructures in humid and oxygen rich environments using in situ quartz crystal microbalance (QCM) and electronic measurements. By correlating electrical measurements with the QCM response, we determine conductivity change as a function of the adsorbed mass of oxygen and water and compare these across different nanostructures in order to investigate the mechanisms behind UV activation of carbon surfaces.


Solid State Lighting and Displays
(ordered chronologically by start date and time)

Single-crystal phosphors for high-brightness white LEDs/LDs
Paper 9768-4

Author(s):  Encarnación G. Víllora, National Institute for Materials Science (Japan), et al.
Conference 9768: Light-Emitting Diodes: Materials, Devices, and Applications for Solid State Lighting XX
Session 1: Nanomaterials and Nanostructures for LEDs I
Date and Time: Monday, February 15, 2016, 11:50 AM

Single-crystal phosphors (SCPs) are attracting recently a considerable attention as alternative to conventional ceramic powder phosphors (CPPs), especially for application in high-brightness white LEDs and LDs. SCPs present two main characteristics in comparison with CPPs: firstly, they exhibit an excellent conversion efficiency and thermal stability, and secondly, they possess an outstanding thermal conductivity in comparison with CPPs embedded in binders. Consequently, even at high irradiances, the temperature of SCPs remains low and their quantum efficiency high, whereas conventional phosphors are already burned out. SCPs are therefore very promising for the emerging the markets of LD-headlights and projection-mapping.


First demonstration of orange-yellow light-emitter devices in InGaP/InAlGaP laser structure using strain-induced quantum well intermixing technique
Paper 9767-9

Author(s):  Mohammed A. Majid, King Abdullah Univ. of Science and Technology (Saudi Arabia), et al.
Conference 9767: Novel In-Plane Semiconductor Lasers XV
Session 2: Materials Developments
Date and Time: Monday, February 15, 2016, 2:40 PM

In this paper, a novel strain-induced quantum well intermixing technique is employed to promote interdiffusion via application of a thick-dielectric encapsulant layer, in conjunction with cycle annealing at elevated temperature. With this technique we have successfully tuned the bandgap of InGaP/InAlGaP structure from 640nm to565nm (~250meV). HRTEM, EELs geometric phase analysis (strain-mapping) and COMSOL-simulation are performed to confirm the strain-induced mechanism. Orange semiconductor-laser, yellow and greenish-yellow LEDs emitting at a wavelength of 608nm, 583nm and 570nm, have been demonstrated from this interdiffusion-process. Total output power of ~4.5mW noted for yellow LED, which is the highest ever reported power on this material system at room temperature.


LEDs for solid-state lighting: searching room for improvements
Paper 9768-11

Author(s):  Sergey Y. Karpov, STR Group-Soft Impact Ltd. (Russian Federation), et al.
Conference 9768: Light-Emitting Diodes: Materials, Devices, and Applications for Solid State Lighting XX
Session 3: High Current Performance and Droop in InGaN LEDs
Date and Time: Monday, February 15, 2016, 4:20 PM

State-of-the art LEDs for solid-state lighting are reviewed with the focus on their efficiency and ways for its improvement. Various schemes of color mixing are discussed and optimal parameters of LEDs providing high-quality white light are estimated. Mechanisms of the LED efficiency losses are considered on the heterostructure, chip, and device levels, including high-current efficiency droop, “green gap”, current crowding, Stokes losses, and various recombination losses. Other factors lowering the LED efficiency, like phase separation in InGaN alloys and plastic relaxation in strained heterostructures, are also considered. Possible room for improvement of III-N and III-P LED efficiency is finally discussed.


3D numerical modeling of the carrier transport and radiative efficiency for InGaN/GaN light-emitting diodes with V-shaped pits
Paper 9768-14

Author(s):  Chi-Kang Li, National Taiwan Univ. (Taiwan), et al.
Conference 9768: Light-Emitting Diodes: Materials, Devices, and Applications for Solid State Lighting XX
Session 3: High Current Performance and Droop in InGaN LEDs
Date and Time: Monday, February 15, 2016, 5:30 PM

In this paper, a V-pit embedded inside the multiple quantum wells (MQWs) LED was studied by a three-dimensional (3-D) stress-strain solver and Poisson, drift-diffusion solver are employed to study the current path, where the quantum efficiency and turn-on voltage will be discussed. The model will be calibrated by PL measurements especially for the parameters of threading dislocation. In our simulation, we found that the V-pit structure would not only enhance the hole percolation length but act as a potential barrier to prevent nonradiative recombination from TD. Finally, we implemented the indium fluctuation model into the V-pit structure and we found the turn-on voltage is earlier compared with the planar LED with indium fluctuations, because the V-pit structure provide more percolation length through sidewall QWs for both the electron and hole.


3-pad flip chip COB LED: Novel approach in lowering thermal resistance thus enabling smaller heat sink on super high-power LEDs
Paper 9768-16

Author(s):  Dongwook Noh, Flip Chip Opto Inc. (United States), et al.
Conference 9768: Light-Emitting Diodes: Materials, Devices, and Applications for Solid State Lighting XX
Session 4: Novel Technologies for LED Design and Fabrication I
Date and Time: Tuesday, February 16, 2016, 8:30 AM


GaN-nanowire-based light-emitting diodes
Paper 9768-25

Author(s):  Lars Samuelson, Lund Univ. (Sweden), et al.
Conference 9768: Light-Emitting Diodes: Materials, Devices, and Applications for Solid State Lighting XX
Session 6: Nanomaterials and Nanostructures for LEDs II
Date and Time: Tuesday, February 16, 2016, 1:30 PM

GaN semiconductor nanowires are highly interesting since they offer routes to dislocation-free materials, and the possibility to reach higher In-concentrations and to design optimal cavities and arrays for optimal control of the out-coupling of light. Today, highly efficient blue and green NW-LEDs in the GaN-InGaN materials system can be fabricated. We expect also to very soon realize efficient yellow and red GaN-based nanowire-based LEDs, which will complete the ideal system for color rendering optimization of tri-color R-G-B or four-color R-Y-G-B individually addressable NW-LEDs. This will offer significant avenues towards application areas within advanced display applications as well as in lighting.


Light emission in the NIR and VIS from SIALON rare-earth-doped thin films for integrated optical devices
Paper 9744-37

Author(s):  Ivan Camps, Consejo Superior de Investigaciones Científicas (Spain), et al.
Conference 9744: Optical Components and Materials XIII
Session 9: Optical Properties of Rare-Earth-Doped Materials
Date and Time: Wednesday, February 17, 2016, 9:40 AM

RE-doped mixed compounds such as oxynitrides are attractive because the matrix composition can be varied in order to tune its optical and electric properties. Wavelength emission tunability is also possible since RE-doped nitrides show a longer wavelength emission compared to oxides due to the smaller electronegativity of N3- over O2-. We show successful emission in the NIR- VIS range of SIALON amorphous thin films doped with Er3+, Eu3+ or Eu2+ ions. The light emission is modified as a function of the RE distribution and concentration. Furthermore control of the Eu oxidation state is achieved and therefore of its spectral emission.


Dislocation-free c-oriented platelets based on GaN nanowire seeds
Paper 9748-48

Author(s):  Lars Samuelson, Lund Univ. (Sweden), et al.
Conference 9748: Gallium Nitride Materials and Devices XI
Session 11: Nanostructures
Date and Time: Wednesday, February 17, 2016, 4:00 PM

There are a number of application-areas in GaN and III-N technologies, wherein device limitations are still the result of dislocations and defect density levels in the semiconductor crystal. Such applications are, for instance, UV-emitting LEDs, red-emitting LEDs, and GaN-based electronics – for high power and RF. In this work, we present a method to fabricate wafer-scale arrays of dislocation-free platelets with smooth c-oriented surfaces. On these c-planes high quality device-layers are grown for electronic and optoelectronic devices. We also show how the technique can be extended to ternary nitride-platelets, for an eventual realization of III-N platelet–wafers of choice (InGaAl) compositions.


Fully transparent thin film transistors based on zinc oxide channel layer and molybdenum doped indium oxide electrodes
Paper 9770-16

Author(s):  Mateusz T. Madzik, Masdar Institute of Science & Technology (United Arab Emirates), et al.
Conference 9770: Advances in Display Technologies VI
Session 4: Driving Algorithm and Electronics
Date and Time: Thursday, February 18, 2016, 3:40 PM

In this work we report the fabrication of thin film transistors (TFT) with zinc oxide channel and molybdenum doped indium oxide (IMO) electrodes, achieved by room temperature sputtering. Hafnium oxide was used as gate dielectric, deposited by atomic layer deposition. A set of devices was fabricated, with varying channel width and length from 5 μm to 300 μm for different deposition parameters. Output and transfer characteristics were then extracted to study the performance of thin film transistors, namely threshold voltage, saturation current and channel mobility, enabling to determine optimal fabrication process parameters. Optical transmission in the UV-VIS-IR are also reported.


Communications
(ordered chronologically by start date and time)

High-precision 3D printing: fabrication of micro-optics and integrated optical packages
Paper 9753-2

Author(s):  Ruth Houbertz, Multiphoton Optics GmbH (Germany), et al.
Conference 9753: Optical Interconnects XVI
Session 1: Novel Optical Waveguide and Interconnect Technologies
Date and Time: Monday, February 15, 2016, 11:00 AM

We present new concepts for micro-optical devices that allow for higher integration and degrees of automation by additive manufacturing. Our two-photon-absorption (TPA) machine achieves surfaces of optical quality. The fabrication process is compatible with ORMOCER® materials of excellent transmission at data and telecom wavelengths. We introduce a new type of grating coupler, which allows to significantly decrease the overall package size. The focus of our discussion is on production speed, reliability, automation and reduction of total process steps for fabrication of electro-optical boards.


Ultrahigh refractive index chalcogenide based copolymers for infrared optics
Paper 9745-11

Author(s):  Soha Namnabat, The Univ. of Arizona (United States), et al.
Conference 9745: Organic Photonic Materials and Devices XVIII
Session 3: Optical Waveguides
Date and Time: Monday, February 15, 2016, 5:00 PM

Here we report a new class of polymers that possess high refractive indices and superior optical transmission in the infrared. Using a new technique called inverse vulcanization, which consists of crosslinking linear sulfur polymer chains with organic molecules, we were able to obtain refractive indices in the range of 2. These polymers also demonstrate high transparencies within the near, short-wave and mid-wave infrared, where hydrocarbon based polymers are highly absorbing. In order to further increase the refractive index, additional chalcogenide elements were incorporated; applications of such polymers in mid-infrared photonics, compact optical elements and dense photonic circuits will be discussed.


Planar polymer and glass graded index waveguides for data centre applications
Paper 9753-16

Author(s):  Richard C. Pitwon, Seagate Systems (UK) Ltd. (United Kingdom), et al.
Conference 9753: Optical Interconnects XVI
Session 4: Electrical-Optical PCB Technologies
Date and Time: Tuesday, February 16, 2016, 8:30 AM

Embedded optical waveguide technology for printed circuit boards has advanced considerably over the past decade both in terms of materials and achievable waveguide structures. We report on the suitability of graded index polymer waveguides, fabricated using the Mosquito method, and graded index glass waveguides, fabricated using ion diffusion on thin glass foils, for deployment within future data centre environments. To this end, we characterise the wavelength dependent performance of the different waveguide types as part of an optically disaggregated data storage system and with respect to different common high speed data protocols used at the intra and inter rack level.


Optical links sizing for future broadband geostationary satellite feeder
Paper 9739-22

Author(s):  Sylvain Poulenard, Airbus Defence and Space SAS (France), et al.
Conference 9739: Free-Space Laser Communication and Atmospheric Propagation XXVIII
Session 7: Systems Engineering II: Analysis
Date and Time: Tuesday, February 16, 2016, 10:30 AM

An optical link based on a multiplex of wavelengths at 1.55µm is foreseen to be a valuable alternative to the conventional radio-frequencies for the feeder link of the next-generation of high throughput geostationary satellite. A preliminary optical feeder link system for a 600Gbps bent-pipe satellite is described. The required availability of the link is achieved thanks to a network of geographically spread optical ground stations. Fine pointing mirrors implemented at the ground station compensates in real time for the atmospheric turbulence to reduce both the downlink fiber injection losses and the uplink pointing errors.


Nanolasers and related issues for integrated photonics applications
Paper 9751-4

Author(s):  Cun-Zheng Ning, Arizona State Univ. (United States), et al.
Conference 9751: Smart Photonic and Optoelectronic Integrated Circuits XVIII
Session 2: Plasmonic Nano-Lasers, Antennas, and Structures
Date and Time: Tuesday, February 16, 2016, 3:40 PM

On-chip photonic integration requires light sources of small foot print, high bandwidth, and high energy-data-rate efficiency. Currently lasers meeting all these requirements are still need to be developed. In this talk we will describe our efforts in the last few years in developing metallic cavity nanolasers. Issues such as energy data rate efficiency, modulation speed, noise, thermal performance, as well as their relationship with device size will be described. Recent results on new generation of nanolaser design and fabrication will be also presented including metallic cavity nano-membrane lasers.

Important Dates

Author Notification
26 September 2016

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