A model for low temperature interface passivation between amorphous and crystalline silicon

Excellent passivation of the crystalline surface is known to occur following post-deposition thermal annealing of intrinsic hydrogenated amorphous silicon thin-film layers deposited by plasma-enhanced chemical vapour deposition. The hydrogen primarily responsible for passivating dangling bonds at the crystalline silicon surface has often been singularly linked to a bulk diffusion mechanism within the thin-film layer. In this work, the origins and the mechanism by which hydrogen passivation occurs are more accurately identified by way of an interface-diffusion model, which operates independent of the a-Si:H bulk. This first-principles approach achieved good agreement with experimental results, describing a linear relationship between the average diffusion lengths and anneals temperature. Similarly, the time hydrogen spends between shallow-trap states is shown to decrease rapidly with increases in temperature circuitously related to probabilistic displacement distances. The interface reconfiguration model p...