Free-carrier absorption in n-type gallium arsenide films for polar optical phonon scattering

Abstract

The free-carrier absorption in n-type GaAs films has been investigated for quantum well structures fabricated from III-V semiconducting materials where polar optical phonon scattering is predominant. Attention is given mainly to the case where the electromagnetic radiation is polarized in the layer plane, and the processes involving both emission and absorption of polar optical phonons. The energy band of electrons in semiconductors is assumed to be nonparabolic. Results are shown that the free-carrier absorption coefficient in n-type GaAs films depends upon the photon frequency, the width of the quantum wells, and temperature. However, in the small quantum well region such as the width of quantum wells d<30 Angstrom, the free-carrier absorption coefficient will be independent of temperature. Moreover, the free-carrier absorption coefficient oscillates with the width of quantum wells for larger quantum wells. (C) 1996 American Institute of Physics.