X-Ray, Raman and Photoluminescence Study of Vacancy Ordered ?-Ga2Se3 under High Pressure

Abstract

The effect of pressure on the structure and optical properties of vacancy-ordered β-Ga2Se3 has been investigated by X-ray diffraction, Raman and photoluminescence spectroscopies using diamond anvil cell. From the shift of the photoluminescence peak with pressure, the pressure dependence of the band gap energy (dEg/dP) is derived to be 46 meV/GPa. From Rietveld analysis, the pressure dependencies of the lattice parameters and the atomic positions are obtained. The relation between these crystal data and the pressure dependence of the band gap energy is discussed. From the X-ray measurements, a structural phase transition at 14 GPa is observed, as is observed in α-Ga2Se3. In the Raman scattering measurement, pressure-tuned resonant phenomenon is observed near 2.5 GPa, where the band gap energy of β-Ga2Se3 coincides with the photon energy of the argon ion laser (λ = 514.5 nm) used for Raman measurement as excitation light.