Boron-doped a-Si:Hc-Si interface passivation: Degradation mechanism

The authors report that for a-Si:Hc-Si heterostructure solar cell fabrication the presence of a boron-doped a-Si:H (p+) overlayer may cause H2 effusion from a (few nanometers) thin underlying intrinsic a-Si:H (i) film at moderate temperatures. This phenomenon is in agreement with losses in the electronic passivation quality of c-Sia-Si:H (i) a-Si:H (p+) structures occurring during low temperature (≤260 °C) postdeposition annealing. Consequently, it is argued that such passivation degradation is due to Si-H rupture in the a-Si:H (i) film, likely resulting in Si dangling bond defects, mediated by the presence of the doped layer.