Improved Light Extraction Efficiency of GaN Based Blue Light Emitting Diode Using Nano-Scaled Patterned Sapphire Substrate

Abstract

In this study, two different conical-shape nano-patterns were fabricated on the 2-inch diameter sapphire wafer in order to improve the efficiency of light-emitting diodes. The conical-shape nano-patterns were fabricated on the sapphire wafer using a nanoimprint technique and dry etching method. A blue LED structure was grown on the nanoscale-patterned sapphire substrates. The photoluminescence and electroluminescence were measured to confirm the effectiveness of the nano-scale patterns. An improvement in the luminescence efficiency was observed in case that nano-patterned sapphire substrate was used; a 1.44 times-higher photoluminescence intensity and a 1.5 times-higher electroluminescence intensity were observed, compared to those of the light-emitting diodes structure grown on a conventional flat sapphire wafer.