Low-band-gap front-surface barriers for GaAs solar cells

An investigation was conducted of the effectiveness of passivating the front surface of p/n GaAs solar cells with p⁺⁺-Al_x Ga_1-xAs barriers/windows having little or no Al (x =0.00 to 0.35). The thin, heavily doped window layer also serves as a contact layer, eliminating the need for a cap etch. Such cells might prove to be more stable, simpler, and less expensive to manufacture than the currently more popular heterostructure designs which have window layers containing 80-90% Al covered by thick GaAs cap layers. In the all-GaAs cells fabricated, the short-circuit current was 10% less than typical of their standard heteroface cells. However, it was found that cells with a small amount of Al (~20%) in the window layer could be just as efficient as cells made using the conventional heteroface design