Temperature dependence of the fundamental energy gap in GaAs

We show that the temperature dependence of the fundamental gap energy E₀ of GaAs can be theoretically described within the empirical local pseudopotential approach for the band structure. For the calculation we take into account the thermal expansion effect and two contributions of the deformation potential type electron-phonon interaction. These are the Debye-Waller part, which shifts the gap to lower energies with increasing temperature, and the self-energy part, which partly cancels the shift caused by the Debye-Waller part.