Effect of Crystalline Quality on Photovoltaic Performance for Solar Cell Using X-Ray Reciprocal Space Mapping
ABSTRACT This paper presents the In0.17Ga0.83As solar cell grown on misoriented GaAs substrate (2°- and 15°-off) by metalorganic chemical vapor deposition. The crystalline quality of the In0.17Ga0.83As solar cell is determined by X-Ray reciprocal space mapping (RSM). RSM results show that the crystalline quality of In0.17Ga0.83As solar cell grown on 2°-off GaAs substrate is better than that of 15°-off GaAs substrate. Moreover, the photovoltaic performance of In0.17Ga0.83As solar cell grown on 2°-off GaAs substrate is found to be better than that of In0.17Ga0.83As solar cell grown on a 15°-off GaAs substrate, because the InxGa1-xAs epilayer grown on 15°-off GaAs substrate shows a large strain relaxation in the active layer of the solar cell. A large strain relaxation causes high dislocation density at the initial active layer/InxGa1-xAs graded layer interface for the solar cell grown on 15°-off GaAs substrate. The effect of dislocation defects on the solar cell performance can be alleviated using the p-i-n structure as the epilayer grown on 15°-off GaAs substrate.