Temperature dependence of the refractive index of direct band gap semiconductors near the absorption threshold: Application to GaAs

Using a semiempirical model of the dielectric constant taking excitonic effects correctly into account, we calculate dn/dT for direct band gap semiconductors by separating the contribution of the excitonic enhancement near the band gap energy E(g) from a background term described by the high frequency dielectric constant epsilon(infinity). Comparison of the model with experimental data suggests that dE(g)/dT approximate to 4,5 x 10(-4) eV K-1 and d epsilon(infinity)/dT approximate to 1.32x10(-4) K-1 for GaAs at room temperature, a significant shift from the currently accepted values of these parameters. (C) 1996 American Institute of Physics.