Photoinduced free-carrier absorption in microcrystalline silicon

Photoinduced absorption was observed in microcrystalline Si:H. The wavelength dependence was fit well by λ^γ with γ between 1.5 and 1.8 indicating absorption by free carriers. The induced absorption was much stronger than in single crystal Si; it decreased exponentially with temperature; and increased sublinearly with excitation intensity. These observations are interpreted in terms of a model in which the observed free-carrier absorption occurs in the grains but the recombination process is governed by the amorphous matrix.