Further Improvement in the Light Output Power of InGaN-Based Light Emitting Diodes by Patterned Sapphire Substrate with KOH Wet-Chemical Etching on Sidewall

摘要

This paper presented the fabrication and measurements of InGaN/GaN multiple-quantum well (MQW) light-emitting diodes (LEDs), using patterned sapphire substrate (PSS) combined with roughening technique of KOH wet-chemical etching on chip sidewall, further improvement in the light output power of InGaN-based LEDs could be obtained. For the LED with PSS structure, we can get better light extraction and higher light output power (11.5% at 20 mA) than that of the reference LED. As for the LED with PSS structure and KOH etching on sidewall, it exhibits further enhancement in light extraction and we can get the highest light output power (17.3% at 20 mA) compared with that of the reference LEDs without PSS and KOH treatment. In the results of our experiments, the roughening technique of KOH etching, reducing the totally internal reflection at LED sidewall, was demonstrated to be a simple, cost-effective and feasible method, without expensive or complicated instruments, to further improve the light extraction of InGaN-based LEDs significantly.