Temperature dependence of Raman scattering and luminescence of the disordered Zn0.5Cd0.5Se alloy

We report on luminescence and Raman scattering measurements of zineblende Zn0.5Cd0.5Se thin film grown by molecular beam epitaxy. From the luminescence data of the exciton peak, the dependence of the energy gap with temperature [dE(g)/dT = (4.35 +/- 0.01) X 10(-4) meV/K] and zero-temperature phonon renormalization energy (DeltaE(0) = 30 +/- 1 meV) have been obtained. The broadening of the excitonic emission as the temperature increases is mainly due to scattering processes with longitudinal optical phonons and residual ionized impurities. Raman scattering shows a multiphonon structure, which depends on the temperature. At low temperatures, up to the fifth-order phonon peaks appear due to resonant effects. The increase in the Raman intensity as the temperature decreases is discussed in terms of a model which gives a very good quantitative agreement of the relative intensity between successive phonon peaks. (C) 2002 Elsevier Science Ltd. All rights reserved.