Optical properties of the band-edge exciton in GaSe crystals at 10 K

Abstract

Optical constants (absorption coefficient and refractive index) of unstrained GaSe samples at low temperature have been measured in the vicinity of the band-edge and exciton series. A quantitative fit with Elliott's model is given for the position and intensity of the levels. This does not necessitate any variation of the apparent oscillator strength with thickness (or temperature). Parameters of the tridimensional hydrogenic series obtained from this fit give values of the band gap, the exciton binding energy, the damping of the excited levels, the oscillator strength of the transition, and the reduced effective masses of the exciton.