Recent Progress of AlGaN Deep-UV LED using Transparent Contact Layer

摘要

Deep ultraviolet light-emitting diodes (DUV-LEDs) are attracting much attention for a wide variety of applications, such as sterilization, water purification, medical fields and biochemistry, UV curing, and so on. Through the recent developments of AlGaN DUV LED, high internal quantum efficiency (IQE) more than 60% has been achieved by reducing the threading dislocation density (TDD) of AlN buffer layers. However, the light-extraction efficiency (LEE) is still quite low (usually below 8%), because of a heavy UV absorption through a p-GaN contact-layer. Transparent contact layer is considered to be necessary in order to obtain useful high LEE (50-70%) in DUV LED. We are developing high LEE DUV LEDs by using transparent p-AlGaN contact layer [1, 2].