Band-edge luminescence in quaternary AllnGaN light-emitting diodes

Operation of InGaN multiple-quantum-well (MQW) light-emitting diodes (LEDs) with quaternary AlInGaN barriers at room and elevated temperatures is reported. The devices outperform conventional GaN/InGaN MQW LEDs, especially at high pump currents. From the measurements of quantum efficiency and total emitted power under dc and pulsed pumping, we show the emission mechanism for quaternary barrier MQWs to be predominantly linked to band-to-band transitions. This is in contrast to localized state emission observed for conventional InGaN/InGaN and GaN/InGaN LEDs. The band-to-band recombination with an increased quantum-well depth improves the high-current performance of the quaternary barrier MQW LEDs, making them attractive for high-power solid-state lighting applications. (C) 2001 American Institute of Physics.