Analysis and Control of Deep-Level Defects in Dilute Nitride Semiconductor GaInNAsSb

Deep-level defects in as-grown and annealed dilute nitride semiconductor GaInNAsSb solar cells grown by molecular beam epitaxy were investigated by admittance spectroscopy measurement and compared to determine the mechanism of post-annealing effects on improving the collection of photo carriers. The annealing was confirmed to be effective to decrease nitrogen-related defects in the as-grown GaInNAsSb sample as well as the background carrier concentration. This effect is considered to be mainly responsible for the improved collection of photo carriers. In addition, we found an optimal annealing temperature that suppresses the formation of new defects, leading to a remarkable improvement of the photo carrier collection.