Performance enhancement of nitrogen-polar GaN-based light-emitting diodes prepared by metalorganic chemical vapor deposition.

Abstract

Nitrogen-polar (N-polar) III-nitride materials have great potential for application in long-wavelength light-emitting diodes (LEDs). However, the poor quality of N-polar nitride materials hinders the development of N-polar devices. In this work, we report the enhanced performance of N-polar GaN-based LEDs with an optimized InGaN/GaN double quantum well (DQW) structure grown by metalorganic chemical vapor deposition. We improved the quality of the N-polar InGaN/GaN DQWs by elevating the growth temperature and introducing hydrogen as the carrier gas during the growth of the quantum barrier layers. N-polar LEDs prepared based on the optimized InGaN/GaN DQWs show significantly enhanced (by over 90%) external quantum efficiency and a weakened droop effect compared with a reference LED. More importantly, the optimized N-polar DQWs show a significantly longer emission wavelength than Ga-polar DQWs grown at the same QW growth temperature. This work provides a feasible approach to improving the quality of the N-polar InGaN/GaN QW structure, and it will promote the development of N-polar GaN-based long-wavelength light-emitting devices for micro-LED displays.