Ultraviolet-spectrum Light-emitting Diodes with Omnidirectional Reflectors for High Extraction Efficiency

摘要

This report covers the period August 1st to August 31st 2002 while I was working for Boston University (BU). On September 1st I transferred to Rensselaer Polytechnic Institute (RPI). It is my understanding that this report is required for the transfer of the contract from BU to RPI. The reflective properties of a triple-layer omni-directional reflector have been investigated. The reflector has a two-fold purpose namely it serves as ohmic contact to the top GaN layer of a UV LED and also as a reflector. The reflector consists of the semiconductor (GaN), indium tin oxide (ITO) and a metal layer. It was found that the reflector has reflectivities exceeding 90% for all angles of incidence. Such highly reflective ohmic contacts are desirable as conventional ohmic contacts represent a major loss mechanism in UV LEDs.