Raman spectroscopy and the pressure effect of the diluted magnetic semiconductors Zn1-xMnxSe

Abstract

The Raman spectroscopy of Zn1-xMnxSe thin films with Mn concentration x = 0.04, 0.19 and 0.32 and high pressure induced phase transition of Zn0.76Mn0.24Se crystal are investigated. The energy-dispersive x-ray diffraction (EDXD) is used to study the pressure induced phase transition. It is found the zone-center optical phonons of Zn1-xMnxSe thin films exhibit an intermediate mode behaviour. For Zn0.76Mn0.24Se crystal, three Raman modes: one TO mode at 197.2 cm(-1), one LO mode at 249.4 cm(-1), and a Mn local mode located at 222.5 cm(-1) are found at ambient pressure. The Mn local mode splits into two modes at 4.7 GPa while visible anomaly splittings of TO mode occur at 6.0 and 8.9 GPa. The semiconductor-metal phase transition of Zn0.76Mn0.24Se crystal is observed at 9.6GPa which is 4.8 GPa lower than that of ZnSe crystal. The reduction of the phase transition pressure is ascribed to the increasing of the volume factor of the impurity atom.