Improved light extraction of GaN-based light-emitting diodes by ITO patterning with optimization design

The method of surface patterning of indium tin oxide (ITO) transparent current layer has been investigated in this study to improve the light extraction efficiency of GaN-based light-emitting diodes (LEDs). Optimized design of the patterns on ITO has been performed by ray-tracing simulation and LEDs with different periodic micro-circle structures on ITO have been fabricated. The light output power of the LEDs with the optimal patterns on ITO exhibited 46.4% enhancement compared to the conventional LEDs at 20 mA injection current without electrical degradation. Detailed processing parameters are also provided. It is indicated from the results that the surface-patterned ITO technique could have potential applications in high-power GaN-based LEDs. (C) 2009 Elsevier Ltd. All rights reserved.