Temperature dependence of optical energy gap of GaSe

Summary form only given. Thin films and wafers of cleaved crystalline GaSe were investigated using optical reflectance (R) and transmittance (T) for wavelengths from 200 nm to 1050 nm. The investigations were performed at different temperatures from 77 K to 333 K using a cryogenic microminiature refrigeration system based on the Joule-Thomson effect. The derived spectra of the real part of the refractive index and the absorption coefficient are presented.