Ga0.80In0.20As 1.20-eV high quantum efficiency junction for multijunction solar cells

Abstract
A Ga0.80In0.20As junction for solar cell applications grown on GaAs by organometallic vapor phase epitaxy (OMVPE) with a peak collection quantum efficiency of 92% is reported. This junction is fabricated using step‐graded layers to reduce misfit dislocations between the junction and the substrate. The effects of step grading on the projected short circuit current density, peak quantum efficiency, and diode ideality factor have been measured. With grading, the ideality factor is reduced from n=2.7 to 1.2 for current densities greater than 0.01 A/cm2. This high‐performance Ga0.80In0.20As can serve as an excellent low‐gap junction for multijunction solar cells.