Temperature dependence of absorption coefficient spectra for μc-Si films by resonant photothermal bending spectroscopy

Resonant photothermal bending spectroscopy (R-PBS) has been developed for estimating absorption coefficient spectra of thin film semiconductors. This technique has been applied to hydrogenated microcrystalline silicon (μc-Si:H) films at different measurement temperatures. It is found that absorption coefficient of μc-Si:H films at 0.7–1.1 eV is relevant for the localized states and decreases with increasing measurement temperature. The localized state exists at ∼0.7 eV in the band gap from the band edge. The origin of the absorption is also discussed.