ENERGY-GAP VARIATION IN MIXED III–V ALLOYS

Abstract

Values of E 0 , 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 E 0 with composition can be fitted very well to an equation of the form E 0 = A + Bx + Cx 2 , where x is the mole fraction of one component compound. Such a relation is expected from a virtual-crystal type of analysis.If E 0m is 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 eV 3/2 .