Effects of hole-injection through side-walls of large V-pits on efficiency droop in III–nitride LEDs**Project supported by the National Key Research and Development Project of China (Grant No. 2017YFB0403303) and the Key Technologies Research and Development Program of Tianjin, China (Grant Nos. 18YFZCGX00760 and 18YFZCGX00400).

Abstract

Although the solid-state lighting market is growing rapidly, it is still difficult to obtain ultra-high brightness white light emitting diodes (LEDs). V-pits are inevitably introduced during the metalorganic chemical vapor deposition (MOCVD) growth of multiple quantum wells (MQWs) in III–nitride LEDs, and thus affecting the carrier dynamics of the LEDs. Specifically designed structures are fabricated to study the influence of the V-pits on the hole transportation and efficiency droop, and double quantum wells (QWs) are used to monitor the transportation and distribution of holes based on their emission intensity. It is found that when compared with the planar QWs, the injection of holes into the QWs through the side walls of the V-pits changes the distribution of holes among the MQWs. This results in a higher probability of hole injection into the middle QWs and enhanced emission therein, and, consequently, a lower efficiency droop.