Reflectance and photoluminescence characterization of BexZn1-xTe epilayers

BexZn1-xTe thin films were grown on InP substrates by molecular beam epitaxy (MBE). Optical properties of the epilayers were studied using reflectance and photoluminescence (PL) measurements. An increase in the full width at half maximum of the emission line with the increase in BeTe content was observed and explained by the disorder-induced broadening. The temperature dependence of the band gap energy was determined from reflectance spectra and fitted by semiempirical equation taking into account average phonon energy and electron-phonon interaction. A reduction of the temperature variation of the band gap with the increase in BeTe content was observed. We propose that this effect is due to the decrease of the lattice contribution caused by the lattice hardening properties of BeTe