A precise ray tracing simulation model for GaN based light emitting diodes

Abstract

A simulation model for light extraction efficiency (LEE) was proposed, considering the real structure of GaN-based light emitting diodes and absorption of GaN, electrodes and encapsulation materials, as well as the difference between TE and TM modes, the effects of active layer reabsoption and photo recycling. The slope angle and the depth of the pattern were optimized for patterned sapphire substrates (PSSs). Results show fill factor affects the LEE improvement most and air holes buried in the interface between n-GaN and PSS diminish LEE improvement of the pattern. Then a best improvement of 26% is obtained with the optimized pattern. Especially it is noticeable that the simulated result of LEE (39.2%) and the derived internal quantum efficiency (43.9%) agree well with the experimental results (38%, 45.1% respectively). © 2010 Wiley-VCH Verlag GmbH & Co. KGaA.