Reflectance and thermoreflectance spectra and energy band structure of GeSe crystals

The reflectance spectra of orthorhombic GeSe crystals are studied in the region 0.5 to 12 eV in polarized light with E ∥ a and E ∥ b at 290 K and a Kramers‐Kronig analysis is performed. The thermoreflectance spectra are investigated in the region 1 to 5 eV for E ∥ a and E ∥ b at 300 and 90 K. The energy band structure calculations of GeSe are carried out by the pseudopotential method, and the spectra of the imaginary part of the dielectric constant are calculated by the k · p method. A classification and interpretation of main structures of optical spectra of GeSe by direct interband transitions at critical points T, U, T and high symmetry lines B' V, A is presented on the basis of calculated band structure and selection rules for optical dipole transitions of orthorhombic A4B6 crystals. [Russsian Text Ignored.]