Electroreflectance of GaSe. I. Around 3.4 eV

Abstract

Electroreflectance of layer compound ε-GaSe is measured around 3.4 eV at 77 K and around 3.2 eV at 300 K with the Schottky-barrier technique for the modulation field F parallel to the c-axis and with the transverse electroreflectance for F⊥c, where the light is incident nearly normal to the layers. It is found from the experimental results that the structure is due to an excitonic transition at M₀ critical point. The transition energy is estimated the to be 3382 meV at 77 K and 3225 meV at 300 K, and binding energy of the exciton 9 meV.