Charge carrier absorption in <i>n</i>-type Sb2Se3

The optical and electrical properties of n-type chlorine-doped Sb2Se3 single crystals, with free carrier concentrations above 1016 cm−3 at room temperature, have been studied. The experiments reveal a strongly polarized temperature-dependent long-wavelength infrared absorption attributable to conduction band electrons within the material. For wavelengths between 1.6 and 6 μm, the room temperature absorption varies as λ2.5±0.3, suggesting that longitudinal optical mode scattering is the dominant electron scattering mechanism. The results are most consistent with the hypothesis that electron transport in Sb2Se3 is band-like and not intrinsically limited by small-polaron self-trapping.