Effect of contact spreading layer on photovoltaic response of InGaN-based solar cells



Different conductive films are used as p-GaN current spreading layers in order to explore photovoltaic action of InGaN/GaN double heterojunction solar cells. It is found that the devices with the 200-nm thick indium-tin oxide (ITO) transparent spreading layers shows a very small decrease in fill factor compared to those with the 3-nm Ni/3-nm Au semitransparent metal, but the former demonstrates an enhancement of short-circuit current density by 24% due to the increased amount of light that reaches the solar cell. This improvement in usable light is shown by the increase in transmission and external quantum efficiency.