Temperature Dependence of the Energy Gap in GaAs and GaP

Abstract

Absorption measurements from 300°–973°K for GaAs and to 1273°K for GaP were made in order to determine the energy gap E_g of these materials at high temperatures. These data, together with previously published results, show that the energy‐gap width may be represented by a simple expression for all temperatures. As a function of the absolute temperature T, the direct gap in GaAs is given by E_g=1.522−5.8×10⁻⁴T² / (T+300) eV, and the indirect gap in GaP is given by E_g=2.338−6.2×10⁻⁴T² / (T+460) eV. The general form of the expression for the energy gap is E_g=E_g(0)−aT² / (T+β), where E_g(0) is the energy gap at 0°K, β is approximately the 0°K Debye temperature, and a is an empirical constant.