Date of Award

1-1-2009

Document Type

Campus Access Dissertation

Department

Electrical Engineering

First Advisor

Mohammod A. Khan

Abstract

Light Emitting Diodes (LEDs) are finding numerous applications in several commercial systems because they have unique properties. LEDs are more energy efficient, robust, small in size, very reliable and are sustainable in hazardous environmental conditions making them a good substitute for existing light sources in home lighting, displays, data storage and transmission, and street and automobile lighting.

Cost is one of the key issues that still limit the substitution of conventional light sources with solid-state LED lighting. The cost issue is intimately tied to the overall system power conversion efficiency as it dictates the number of light emitting diodes needed to produce a certain light output power. The system power conversion efficiency itself is dictated by the LED internal quantum efficiency (IQE), the light extraction and the efficiency and the device package.

In this dissertation, an effort has been made to improve the overall efficiency of III-N LED devices by controlling the process parameters which are used to fabricate the device and the device design. More specifically we have targeted deep ultraviolet (DUV) LEDs and blue-green light emitting diodes. The epilayer structures for the DUV LEDs are primarily based on high aluminum content AlGaN and that for the blue green comprise of GaN and InGaN. Hence the focus of our thesis is to devise new schemes for a better processing of high Al-content AlGaN, GaN and InGaN layers. We have also devised new schemes to improve the light extraction efficiency as well.

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