Doping induced effects, surface/interface

Some metastable centers may be associated with doped layers or with interface states. The light-induced generation of these centers appears to increase the surface recombination velocity in some cells, causing a decrease in the spectral response at short wavelengths. This effect and the others mentioned above are reversible annealing the a-Si H cells at 200°C for several minutes restores the cells to their initial conditions. 

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