Wide depletion width of 1 eV GaInNAs solar cells by thermal annealing

We present high quality GaInNAs p-i-n solar cells with depletion widths in excess of 1 m for material absorbing in the practically important 1 eV band gap regime. This is achieved through optimization of post-growth rapid thermal annealing at a temperature of ∼ 910 C. Despite the improvements in material quality evidenced by a low background impurity concentration and improved minority carrier collection, the external quantum efficiency remains limited to ∼50. This is attributed to losses due to efficient radiative recombination in the bulk GaInNAs intrinsic region enhanced via localization of carriers in alloy fluctuations.