Efficiency enhancement of III-nitride light-emitting diodes with strain-compensated thin-barrier InGaN/AlN/GaN multiple quantum wells

Abstract

We introduced strain-compensated thin-barrier indium gallium nitride (InGaN)/aluminum nitride (AlN)/gallium nitride (GaN) multiple quantum wells (MQWs) to replace thin-barrier InGaN/GaN MQWs. The AlN insert layers would effectively compensate the strain of the thin-barrier InGaN/GaN MQWs to improve the opto-electrical properties of light-emitting diodes (LEDs). The 120-mA light output power of thin-barrier InGaN/GaN MQW LEDs could be improved from 31.9 mW to 35.3 mW by introducing 20-s-growth AlN insert layers, possibly reaching almost the same 120-mA light output power of traditional thick-barrier InGaN/GaN MQWs. Moreover, the current dependent external quantum efficiency (EQE) of the thin-barrier InGaN/AlN/GaN MQW LEDs with 20-s-growth AlN insert layers also indicated the largest peak EQE, showing high efficiency in low current injection. The severe carrier overflow effect that degrades the light output efficiency of the thin-barrier InGaN/GaN MQW LED in high current injection can be suppressed by introducing thin-barrier InGaN/AlN/GaN MQW with 20-s-growth AlN insert layers.