Raman study of phonon modes and disorder effects in Pb1-xSrxSe alloys grown by molecular beam epitaxy -: art. no. 013513

We report phonon modes and alloy disorder effects of Pb1-xSrxSe alloys (x <= 0.3) grown on BaF2 (111) substrates by Raman spectroscopy measurements. On the basis of phonon modes in binary PbSe and SrSe, first-, second-, and high-order Raman scattering phonon frequencies of ternary Pb1-xSrxSe are observed, together with the deduction of the disorder activated modes due to the breakdown of the selection rule. The alloy disorder is found to play a more important role than the strain effect in Pb1-xSrxSe, and has been further investigated by employing the special correlation model. The PbSe-like second-order features are also shown to broaden slightly and diminish in intensity with increasing Sr concentration, which has been attributed to a weak breakdown in the long-range order. (c) 2006 American Institute of Physics.