Band Structure and Transport Properties of Some 3–5 Compounds

Abstract

The experimental information relevant to the band structure of the compounds InSb, InAs, GaSb, GaAs, GaP, AlSb and some of their alloys is synthesized and interpreted in terms of a consistent theoretical picture which exploits the close relationship linking the band structures of the group 4 and 3–5 semiconductors. It is shown that the momentum matrix element determining the conduction band masses in those compounds whose edge is of symmetry type Γ1, is nearly constant. Simple theoretical expressions, agreeing well with experiment, are derived for the corresponding effective masses and valence band spin-orbit splittings, following Kane's theory for InSb. The dominant scattering mechanisms determining the transport properties are reviewed briefly. Arguments are presented which show deformation potential scattering to be unimportant relative to polar optical mode scattering. A heuristic treatment indicates that the relaxation time approximation can be applied reasonably to polar scattering for temperatures T>ℏωl/K, where ωl is the longitudinal optical frequency. Multiband transport effects are discussed with special reference to the Nernst effect in GaAs and the electron mobility in GaSb. An explanation of the high-temperature behavior of the Nernst coefficient in GaAs in terms of polar and intervalley scattering is proposed. The mobility in GaSb remains unexplained.