Analysis of light-induced degradation mechanisms in $\alpha$-Si:H/$\mu$-Si:H solar photovoltaics

The photoinduced degradation of the $i$-$\alpha$-Si:H layer in tandem photovoltaic converters based on $\alpha$-Si:H/$\mu$-Si:H structures is analyzed in terms of the “H-collision-” and “floating-bond” models and modifications of these. It is shown that the form of the degradation dependence is well described by all models under consideration. Compared with the modified models, the original “H-collision-” and “floating-bond” models yield estimates for saturated dangling-bond concentrations, which are always dependent on the intensity of the light that caused the degradation. The modified “floating-bond” model makes it possible to exclude this dependence, and the modified “H-collision” model describes the occurrence of this dependence in a certain range of illumination intensities and its absence in another range, which is in best agreement with experimental data.