Investigations of layered semiconductors using photoreflectance

Crystalline GaSe was investigated using optical reflectance stimulated by additional illumination of the sample. The investigations were performed at room temperature for wavelengths from 400 nm to 1100 nm. The additional illumination was obtained using Ar laser radiation (λ = 488 nm) chopped with different frequencies (up to 4 kHz). The obtained photoreflectance spectral characteristics were fitted with the appropriate theoretical dependence to obtain critical energy of the investigated material. The obtained results have been compared with the literature data as well as the results of the performed standard investigations of optical transmittance, reflectance, photoconductivity and photoelectromagnetic effect. (author)