Efficiency Improvement of Short-Period InGaN/GaN Multiple-Quantum Well Solar Cells With ${\hbox{H}} _{2}$ in the GaN Cap Layer

The thick-well InGaN/GaN short period multiple quantum well solar cells (SCs) with H 2 in the GaN cap layer exhibits an improved open-circuit voltage, fill factor, and conversion efficiency ( η%) compared with those of SCs without the ramped H 2 in the GaN cap layer. The η% of the SC with the ramped H 2 in the GaN cap layer (0.77%) shows a 67.4% improvement compared with that of the SC without the ramped H 2 (0.46%). Furthermore, the η% of SC with patterned sapphire substrate (PSS) (1.36%) indicates a 76.6% improvement compared with that of SC without PSS (0.77%).