THE TEMPERATURE-DEPENDENCE OF THE BAND-GAPS IN INP, INAS, INSB, AND GASB

We calculate the dependence of the direct band gaps E0 on temperature in the narrow-gap materials InP, InAs, InSb, and GaSb. Our calculation is based on the Allen-Heine approach and includes two effects: (i) thermal expansion and (ii) electron-phonton interaction. The latter when expanded in perturbation theory up to second order in the atomic displacements includes two terms: Debye-Waller and self-energy (or Fan-) terms. The results obtained by including all these terms within the rigid-pseudoion model compare reasonably well with available experimental results.