Pressure-induced metallic phase transition in gallium arsenide up to 24.3 GPa under hydrostatic conditions

Abstract

A series of experiments of structural, vibrational and electrical transport characterization of gallium arsenide (GaAs) have been performed up to 24.3 GPa under hydrostatic conditions in a diamond anvil cell (DAC) in conjunction with in situ Raman scattering spectroscopy, electrical conductivity measurements, high-resolution transmission electron microscopy (HRTEM) and atomic force microscopy (AFM). Upon compression, a phase transition from the zinc-blende (zb) to the orthorhombic (Cmcm) structure of GaAs was observed at 12.2 GPa through the discontinuous variations of the Raman shifts, Raman full-width at half-maximum values and electrical conductivity. Furthermore, the results of variable temperature electrical conductivity experiments confirmed that the high-pressure phase (Cmcm) exhibited one obvious metallic behavior. Upon decompression, the Raman scattering results of the recovered sample under ambient conditions indicated that the phase transition was reversible under hydrostatic conditions. The reversibility of the phase transition was further verified by HRTEM and AFM images for the recovered sample.