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Proceedings Paper

Dominant transverse-electric polarized emission from 298 nm MBE-grown AlN-delta-GaN quantum well ultraviolet light-emitting diodes
Author(s): Cheng Liu; Yu Kee Ooi; S. M. Islam; Huili Grace Xing; Debdeep Jena; Jing Zhang
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Paper Abstract

III-nitride based ultraviolet (UV) light emitting diodes (LEDs) are of considerable interest in replacing gas lasers and mercury lamps for numerous applications. Specifically, AlGaN quantum well (QW) based LEDs have been developed extensively but the external quantum efficiencies of which remain less than 10% for wavelengths <300 nm due to high dislocation density, difficult p-type doping and most importantly, the physics and band structure from the three degeneration valence subbands. One solution to address this issue at deep UV wavelengths is by the use of the AlGaN-delta-GaN QW where the insertion of the delta-GaN layer can ensure the dominant conduction band (C) - heavyhole (HH) transition, leading to large transverse-electric (TE) optical output. Here, we proposed and investigated the physics and polarization-dependent optical characterizations of AlN-delta- GaN QW UV LED at ~300 nm. The LED structure is grown by Molecular Beam Epitaxy (MBE) where the delta-GaN layer is ~3-4 monolayer (QW-like) sandwiched by 2.5-nm AlN sub-QW layers. The physics analysis shows that the use of AlN-delta-GaN QW ensures a larger separation between the top HH subband and lower-energy bands, and strongly localizes the electron and HH wave functions toward the QW center and hence resulting in ~30-time enhancement in TEpolarized spontaneous emission rate, compared to that of a conventional Al0.35Ga0.65N QW. The polarization-dependent electroluminescence measurements confirm our theoretical analysis; a dominant TE-polarized emission was obtained at 298 nm with a minimum transverse-magnetic (TM) polarized emission, indicating the feasibility of high-efficiency TEpolarized UV emitters based on our proposed QW structure.

Paper Details

Date Published: 16 February 2017
PDF: 8 pages
Proc. SPIE 10104, Gallium Nitride Materials and Devices XII, 101041R (16 February 2017); doi: 10.1117/12.2252487
Show Author Affiliations
Cheng Liu, Rochester Institute of Technology (United States)
Yu Kee Ooi, Rochester Institute of Technology (United States)
S. M. Islam, Cornell Univ. (United States)
Huili Grace Xing, Cornell Univ. (United States)
Debdeep Jena, Cornell Univ. (United States)
Jing Zhang, Rochester Institute of Technology (United States)

Published in SPIE Proceedings Vol. 10104:
Gallium Nitride Materials and Devices XII
Jen-Inn Chyi; Hiroshi Fujioka; Hadis Morkoç; Yasushi Nanishi; Ulrich T. Schwarz; Jong-In Shim, Editor(s)

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