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Proceedings Paper

InGaN MQW green LEDs using p-InGaN and p-InGaN/p-GaN superlattices as p-type layers
Author(s): Russell D. Dupuis; Jae B. Limb; Jianping Liu; Jae-Hyun Ryou; Clarissa Horne; Dongwon Yoo
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Paper Abstract

High-efficiency "true" green light-emitting diodes (LEDs) (λ~550nm) are one of the key elements in realizing high-brightness RGB-based white-lighting systems. Because the InGaN multiple quantum wells (MQWs) in the active regions of green LEDs contain a high indium alloy composition and a corresponding large lattice mismatch, the QW has a reduced material quality and contains large piezoelectric fields induced by the large strain. The piezoelectric field reduces the overlap of the electron-hole wave functions, and so results in reduced internal quantum efficiency in green LEDs. In addition, other effects can strongly impact InGaN materials with high indium content, e.g., detrimental annealing of the MQW active region during the subsequent growth of the p-type hole injection and contact layers. In this study, the optical and structural characteristics of green LEDs employing p-InGaN and p-InGaN/p-GaN superlattices (SLs) were examined. For the LEDs with a p-In0.04Ga0.96N:Mg layer grown at 840°C, only a slight decrease in PL intensity was observed compared to similar structures grown without a p-layer. However, pits are observed for p- In0.04Ga0.96N:Mg layers, which may cause increased reverse current leakage. In order to decrease the reverse leakage current, p-InxGa1-xN/p-GaN SLs were developed. The hole concentration of the p-InxGa1-xN/p-GaN SLs is close to that of p-In0.04Ga0.96N, and is much higher than that of p-GaN grown at an acceptably low temperature. In addition, pits disappear in optimized p-InxGa1-xN/p-GaN SLs. In order to study the structural and optical characteristics of green LEDs with p-In0.04Ga0.96N and p-InxGa1-xN/p-GaN SL layers, I-V characterization and electroluminescence measurements were performed and the results will be described in detail.

Paper Details

Date Published: 15 February 2008
PDF: 8 pages
Proc. SPIE 6894, Gallium Nitride Materials and Devices III, 68941D (15 February 2008); doi: 10.1117/12.766915
Show Author Affiliations
Russell D. Dupuis, Georgia Institute of Technology (United States)
Jae B. Limb, Georgia Institute of Technology (United States)
Jianping Liu, Georgia Institute of Technology (United States)
Jae-Hyun Ryou, Georgia Institute of Technology (United States)
Clarissa Horne, Georgia Institute of Technology (United States)
Dongwon Yoo, Georgia Institute of Technology (United States)

Published in SPIE Proceedings Vol. 6894:
Gallium Nitride Materials and Devices III
Hadis Morkoç; Cole W. Litton; Jen-Inn Chyi; Yasushi Nanishi; Euijoon Yoon, Editor(s)

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