High-Pressure Behaviour of the Exciton and the Absorption Edges in Ga Se

From a study on the optical absorption edge of Ga Se under hydrostatic pressure up to 14 kilobars, it is shown that the indirect gap energy decreases with pressure faster than the direct edge and the exciton level associated with it. Increasing overlap of the indirect edge and the direct exciton causes enhanced interference between the exciton line and the continuum of structure due to indirect transitions, which depletes the exciton strength under pressure.