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

Micro-Raman and photoluminescence (PL) studies of a ZnxCd1-xSe (x=0.68) thi n film sample have been carried out under high pressure at room temperature . In the PL spectra, the PL energy gap shift exhibits sublinearity with pre ssure and a least-square fitting to the experimental data gives pressure co efficients of alpha = 0.082 eV/GPa and beta = -0.0052 eV/GPa(2). The second -order pressure coefficient beta of the energy gap obtained experimentally is anomalously large and its origin was explained by alloy potential fluctu ation with increasing pressure. From the Raman spectra, the first-order pre ssure coefficient was also calculated using least-square fitting. The low e nergy tail of the longitudinal-optical phonon was found to develop with pre ssure and the line shape change with pressure is interpreted in terms of a ''spatial correlation" model. (C) 1998 American Institute of Physics. [S002 1-8979(98)05021-X].