Pressure-dependent Raman scattering and photoluminescence of Zn1-xCdxSe epilayers

Abstract

Raman and photoluminescence spectra of cubic Zn1-xCdxSe (0 <= x <= 0.32) epilayers were obtained at high pressure. The impurity mode I observed in the phonon Raman spectra at low temperature confirms the intermediate phonon mode behavior. A split transverse optical phonon mode was found in the down-stroke high-pressure Raman scattering. Additionally, the pressure-dependent longitudinal optical (LO) phonon frequencies and the Gruneisen parameter (gamma(LO)) were obtained by quadratic polynomial fitting. Pressure-driven resonant Raman scattering effect was observed in samples with a high Cd concentration (x >= 0.18). The critical pressure of semiconductor-to-metal phase transition (Pt) decreases as the Cd content increases. As the Cd concentration increases from 0 to 0.32, Pt falls from 13.6 to 9.4 GPa, according to Pt (GPa)=13.6-6.8x-20.3x(2). (c) 2007 American Institute of Physics.