Room-Temperature Photoluminescence in Layered ?-GaSe, GaSe0.9S0.1, GaSe0.8S0.2 under Pressure

Photoluminescence spectra of the direct free excitons and strain-induced states in e-GaSe, GaSe0.9S0.1, and GaSe0.8S0.2 under hydrostatic pressure up to 1 GPa are reported for the first time. Red-shift and broadening with pressure were detected for all bands. The pressure coefficients of the direct free excitons and strain-induced states were determined and compared with those existing in literature.