Optical Properties of GeS

Reflectance and thermoreflectance are measured of single‐crystal GeS in the energy range of 1.2 to 5.2 eV in polarized light with orientations E ∥ a and E ∥ b. Kramers‐Kronig analysis is applied to all curves. Thus ε;1, ε2, Δε1, and Δε2 are obtained which are used together with the band structure of GeS calculated by Grandke and Ley and with the derived selection rules as a basis for the assignment of the characteristic energies to direct interband transitions at some symmetry points and along symmetry lines in the Brillouin zone. Some ellipsometric measurements are performed at 632.8 nm.