Boron-doped a-Si:H/c-Si interface passivation:: Degradation mechanism

The authors report that for a-Si:H/c-Si heterostructure solar cell fabrication the presence of a boron-doped a-Si:H(p(+)) overlayer may cause H-2 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-Si/a-Si:H(i)/a-Si:H(p(+)) structures occurring during low temperature (<= 260 degrees 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.