Optical absorption in GaTe under high pressure

This paper reports on the pressure dependence at room temperature of the ab sorption coefficient of the layered semiconductor gallium telluride. The ab sorption edge in the explored pressure range (up to 6.1 GPa) can be account ed for through the superposition and interaction of a direct gap and an ind irect gap. The pressure shift of the direct gap is strongly nonlinear, star ting at low pressure with a coefficient of -85.7 +/- 0.4 meV/GPa and exhibi ting a minimum at around 2.9 GPa. The exciton binding energy decreases unde r pressure, which can be related to the increase of the dielectric constant . The broadening of the exciton line is explained through phonon-assisted i ntervalley scattering of conduction-band electrons after the crossover betw een direct and indirect gaps, with an estimation of the related intervalley deformation potential.