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

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Abstract
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 °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.