Raman scattering study of (GaAs)(1-x)(Si-2)(x) alloys epitaxially grown onGaAs

(GaAs)(1-x)(Si-2)(x) metastable alloys grown on (001), (110), (112), and (1 11) GaAs substrates, with Si fractions in the range 0 less than or equal to x less than or equal to0.43, were studied by Raman scattering. Two modes ne ar the LO and TO modes of GaAs, besides two local modes associated either w ith Si-As or Si-Ga and Si-Si bonds, are observed in the Raman spectra. The ratio of integrated intensities of TO-like and LO-like modes (I-TO/I-LO) is used to evaluate the short range order. It is observed that the zinc blend e to diamond transition reported in the literature for these alloys does no t influence the Si fraction dependence of the short range order. (C) 2001 A merican Institute of Physics.