Raman spectroscopy study of Zn1-xFexSe under high pressure

Abstract

Zn1-xFexSe, x = 0, 0.018, 0.035 and 0.16, were studied by Raman scattering spectroscopy up to 35.0 GPa, Lt was found that the semiconductor-metal phase transition pressures for these samples are 14.4, 12.8, 12.0 and 10.9 Cpa, respectively. Before the semiconductor-metal phase transition, a visible anomaly of the TO Raman mode splitting was observed at 4.7 and 9.1 GPa for ZnSe, at 3.3 and 5.9 GPa for Zn0.982Fe0.018Se, and at 4.5 and 7.2 Cpa for Zn0.965Fe0.035Se, respectively, while Zn0.84Fe0.16Se showed mode splitting at 4.7 GPa only. For these samples, one of the TO splitting modes exhibits phonon softening (red shift), while the other manifests wavenumber increasing (blue shift) with pressure. For x = 0.018, 0.035 and 0.16, a new Raman mode, which was identified as Fe local mode, was observed between the pure ZnSe LO and TO modes, Fe local mode exhibits blue shift behaviour before metallization and disappears as the pressure is higher beyond the metallization pressure. PACS numbers: 62.50. + p, 64.60. - i, 78.30.Fs. Copyright (C) 1999 John Wiley & Sons, Ltd.