Effect of phonon scattering on free-carrier absorption in n-type indium antimonide films

Abstract

The free-carrier absorption in n-type InSb films has been investigated for carriers confined in quasi-two-dimensional (2D) semiconductors with the nonparabolic energy band of electrons. We discuss the effect of phonon scattering on the free-carrier absorption coefficient (α) for both deformation-potential coupling and piezoelectric coupling. α is found to depend on the photon polarization relative to the direction normal to the quasi-2D structure, the photon frequency, the film thickness, and the temperature. α could be complex due to the interaction between photons, phonons, and electrons. (i) When the acoustic phonon scattering is dominant, α increases with decreasing the film thickness for phonons polarized parallel or perpendicular to the layer plane. It is also shown that α increases with decreasing photon frequency and increasing temperature for photons polarized parallel to the layer plane, while for photons polarized perpendicular to the layer plane the α temperature-dependence is more complicated. (ii) If the piezoelectric scattering is dominant, α is also decreasing with increasing the film thickness for photons polarized parallel or perpendicular to the layer plane. But α decreases with increasing temperature for photons polarized perpendicular to the layer plane. Moreover, numerical results for the parallel polarization are much smaller than those for the perpendicular polarization.