Date of Award

1-1-2011

Document Type

Campus Access Dissertation

Department

Electrical Engineering

First Advisor

Asif Khan

Abstract

This dissertation focuses on improving deep ultraviolet light emitting diodes, by improving the base nAlGaN layer upon which the device layers are grown. The AlN buffer layer, superlattice strain-relieving layer and nAlGaN layer are sequentially and systematically optimized. Rough/Smooth AlN layers are shown to yield the highest quality nAlGaN layers compared to Pulsed Lateral Overgrowth AlN or AlN grown on Patterned Sapphire Substrate. A Rough/Smooth style superlattice with a high number of periods yields the best crystal quality and lowest strain nAlGaN layer. By optimizing the temperature of the nAlGaN layer, and using the optimized AlN and superlattice layers, the off-axis x-ray line width was reduced from ~660 arc seconds to below 500 arc seconds, which corresponds to an estimated 90% reduction in dislocation density. Conductivity and transparency were also improved, by 20% and 15% respectively.

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