Nature of doped a-Si:H/c-Si interface recombination

Doped hydrogenated amorphous silicon (a-Si:H) films of only a few nanometer thin find application in a-Si:H/crystalline silicon heterojunction solar cells. Although such films may yield a field effect at the interface, their electronic passivation properties are often found to be inferior, compared to those of their intrinsic counterparts. In this article, based on H-2 effusion experiments, the authors argue that this phenomenon is caused by Fermi energy dependent Si-H bond rupture in the a-Si:H films, for either type of doping. This results in the creation of Si dangling bonds, counteracting intentional doping of the a-Si:H matrix, and lowering the passivation quality.