Carrier transport via V-shaped pits in InGaN/GaN MQW solar cells**Project supported by the National Natural Science Foundation of China (Grant Nos. 61564007 and 11364034) and the Sci-Tech Support Plan of Jiangxi Province, China (Grant No. 20141BBE50035).

Abstract

Carrier transport via the V-shaped pits (V-pits) in InGaN/GaN multiple-quantum-well (MQW) solar cells is numerically investigated. By simulations, it is found that the V-pits can act as effective escape paths for the photo-generated carriers. Due to the thin barrier thickness and low indium composition of the MQW on V-pit sidewall, the carriers entered the sidewall QWs can easily escape and contribute to the photocurrent. This forms a parallel escape route for the carries generated in the flat quantum wells. As the barrier thickness of the flat MQW increases, more carriers would transport via the V-pits. Furthermore, it is found that the V-pits may reduce the recombination losses of carriers due to their screening effect to the dislocations. These discoveries are not only helpful for understanding the carrier transport mechanism in the InGaN/GaN MQW, but also important in design of the structure of solar cells.