Raman and photoluminescence investigation of ZnxCd1-xSe thin film under high pressure

Abstract

Micro-Raman and photoluminescence (PL) studies of ZnxCd1-xSe (x=0.68) thin film have been carried out under high pressure at room temperature. In the PL spectra, the PL energy gap shift exhibits sublinearity with pressure and a least-square fitting to the experimental data gives a pressure coefficients of α=0.082 eV/GPa and β=-0.0052 eV/GPa2. The second-order pressure coefficient β of the energy gap obtained experimentally is anomalously large and its origin was explained by alloy potential fluctuation with increasing pressure. In the Raman spectra, the first-order pressure coefficient was also calculated by least-square fit. The low energy tail of the longitudinal-optical (LO) phonon was found to develop with pressure for the first time, and the line shape change with pressure is interpreted in terms of a "spatial correlation" (SC) model.