Light Output Enhancement of UV Light-Emitting Diodes With Embedded Distributed Bragg Reflector

Abstract

We demonstrate the output power enhancement of ultraviolet light-emitting diodes (UVLEDs) by epitaxial lateral over-growth (ELOG) on a distributed Bragg reflector (DBR) patterned substrate. The patterned DBR mesas are used as ELOG masks to improve material quality as well as reflectors to enhance the light output coupling. Compared with the conventional UVLEDs, the surface pit density of UVLEDs at regions right above embedded patterned DBR were reduced from 2.5 x 10(6) to 1.6 x 10(6) cm(-2). The improved light extraction efficiency is verified by ray tracing simulation. The luminous intensity of this novel structure is enhanced by 75% compared to that of reference UVLED structure at the wavelength 390 nm.