ENERGY-GAP VARIATION IN MIXED III–V ALLOYS

Abstract

Values of E0, the lowest direct optical transition, are available for several III-V alloy systems, from measurements of optical absorption, electroreflectance, electroluminescence, etc. It is shown that in all available cases the variation of E0with composition can be fitted very well to an equation of the form E0 = A + Bx + Cx2, where x is the mole fraction of one component compound. Such a relation is expected from a virtual-crystal type of analysis.If E0mis the mean of the energy gaps of the component compounds of the system, it is found that an empirical relation of the form [Formula: see text] appears to hold where α is approximately 0.3 eV3/2.