We have investigated the growth and optical properties of a set of BexZn1-x
Te epitaxial layers having different composition, with x ranging from 0-0.7
. Comparison of the reflectivity and the photoluminescence spectra allowed
us to locate the direct-to-indirect band gap crossover for this alloy at x
approximate to0.28. The Gamma --> Gamma direct band gap exhibits a linear d
ependence on composition over the entire compositional range and can be fit
ted to the equation E-Gamma (g)(x)=2.26*(1- x)+4.1*x. It increases linearly
with BeTe content at a rate of 18 meV for a change of 1% in BeTe content.
The Gamma -->X indirect band gap for BexZn1-xTe can be fitted to the equati
on E-X (g)(x)=3.05*(1-x)+2.8*x-0.5*x*(1- x), suggesting that the energy of
the indirect Gamma -->X transition for ZnTe is about 3.05 eV. (C) 2001 Amer
ican Institute of Physics.