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.