Raman analysis of short-range clustering in laser-deposited CdSxTe1-x films

Raman line shapes of the longitudinal optical phonon have been analyzed for the pseudobinary alloy system CdSxTe1-x over the full alloy range. The polycrystalline thin films were grown by pulsed laser deposition at, typically, 370 degrees C including films with x values throughout the miscibility gap (0.06<x<0.97). Peak shift, broadening, and asymmetry arising from spatial correlation effects yield details of the microstructural clustering. The dependence of phonon coherence length on the x value cannot be explained simply from a random occupancy of the anion sublattice. We employed a linear chain model with site probabilities modified by the Warren-Cowley short-range order parameter to infer coherence lengths versus x. The data are best fit with a short-range order parameter of 0.73 at x = 1/2. (C) 1998 American Institute of Physics. [S0003-6951(98)02020-8].