Raman spectroscopy study of Zn1-xMnxSe thin films under high-pressure

Abstract

Raman spectroscopy was used to study phase transitions of substrate-free Zn1-xMnxSe thin films, x=0.07, 0.17, and 0.29, under high pressure up around 20.0 GPa at ambient temperature. One Raman mode, transverse optical split mode, was observed before metallization at 2.9 +/- 1.0, 2.4 +/- 0.8, and 2.1 +/- 0.6 GPa for Zn0.71Mn0.29Se, Zn0.83Mn0.17Se, and Zn0.93Mn0.07Se thin films, respectively. The semiconductor-metallic transition pressure for Zn0.71Mn0.29Se, Zn0.83Mn0.17Se, and Zn0.93Mn0.07Se thin films was observed at 9.4 +/- 0.4, 10.9 +/- 0.6, and 11.7 +/- 0.2 GPa, respectively. It was found that the relation of the ionicity and the reduction of the pressure in transition from semiconductor to metal phase for Zn1-xMnxSe thin films was not the same as that of bulk crystals. The percentage of the increasing of the Gruneison parameter of longitudinal optical mode for semiconductor to metal phase transition might be the important factor inherently related to the reduction of phase transition pressure for substrate-free Zn1-xMnxSe thin film systems. (c) 2007 American Institute of Physics.