Pressure-Dependent Phonon Scattering of Layered GaSe Prepared by Mechanical Exfoliation*

Few-layered gallium selenide (GaSe) is obtained by using the mechanical exfoliation method, and its properties are characterized by photoluminescence and Raman spectroscopy. The pressure-dependent phonon scatterings of bulk, few-layered, oxidized few-layered GaSe are characterized up to 30 GPa by using a diamond anvil cell with inert argon used as the pressure transmission medium. All the GaSe samples processed a phase transition around 28 GPa. A new vibration mode at 250 cm−1 is found in oxidized few-layered GaSe by Raman spectra, which is indexed as the Raman vibration mode of α-Se.