Reflectivity of the ternary compound Ga(1-x)AlxSb from 2 to 5.5 eV

Abstract
The reflectivity of the ternary compound Ga(1-x)AlxSb has been measured on single-crystalline layers from 2 to 5.5 eV for 01, E1+ Delta 1, E'0, E'0+ Delta '0 and E2 with the composition x is reported. A parabolic variation is found for E1, E1- Delta 1 and Delta 1, whereas the E2 transition varies linearly with x. As for the variation of E1, the experimental bowing is compared to that calculated by the dielectric two-band method in the virtual crystal approximation, to which a term due to the effects of aperiodicity is added.