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Proceedings Paper

Estimation of free carrier concentrations in high-quality heavily doped GaN:Si micro-rods by photoluminescence and Raman spectroscopy
Author(s): M. S. Mohajerani; S. Khachadorian; C. Nenstiel; T. Schimpke; A. Avramescu; M. Strassburg; A. Hoffmann; A. Waag
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Paper Abstract

The controlled growth of highly n-doped GaN micro rods is one of the major challenges in the fabrication of recently developed three-dimensional (3D) core-shell light emitting diodes (LEDs). In such structures with a large active area, higher electrical conductivity is needed to achieve higher current density. In this contribution, we introduce high quality heavily-doped GaN:Si micro-rods which are key elements of the newly developed 3D core-shell LEDs. These structures were grown by metal-organic vapor phase epitaxy (MOVPE) using selective area growth (SAG). We employed spatially resolved micro-Raman and micro-photoluminescence (PL) in order to directly determine a free-carrier concentration profile in individual GaN micro-rods. By Raman spectroscopy, we analyze the low-frequency branch of the longitudinal optical (LO)-phonon-plasmon coupled modes and estimate free carrier concentrations from ≈ 2.4 × 1019 cm−3 up to ≈ 1.5 × 1020 cm-3. Furthermore, free carrier concentrations are determined by estimating Fermi energy level from the near band edge emission measured by low-temperature PL. The results from both methods reveal a good consistency.

Paper Details

Date Published: 8 March 2016
PDF: 7 pages
Proc. SPIE 9768, Light-Emitting Diodes: Materials, Devices, and Applications for Solid State Lighting XX, 976803 (8 March 2016); doi: 10.1117/12.2212890
Show Author Affiliations
M. S. Mohajerani, Technische Univ. Braunschweig (Germany)
S. Khachadorian, Technische Univ. Berlin (Germany)
C. Nenstiel, Technische Univ. Berlin (Germany)
T. Schimpke, OSRAM Opto Semiconductors GmbH (Germany)
A. Avramescu, OSRAM Opto Semiconductors GmbH (Germany)
M. Strassburg, OSRAM Opto Semiconductors GmbH (Germany)
A. Hoffmann, Technische Univ. Berlin (Germany)
A. Waag, Technische Univ. Braunschweig (Germany)

Published in SPIE Proceedings Vol. 9768:
Light-Emitting Diodes: Materials, Devices, and Applications for Solid State Lighting XX
Heonsu Jeon; Li-Wei Tu; Michael R. Krames; Martin Strassburg, Editor(s)

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