Optical properties and electronic band structure of SnS single crystals

Reflection and absorption spectra of SnS single crystals (Pnma (D-2h(16)) space group) were investigated at low and room temperatures. Features attributed to three excitonic states were found out. Parameters of excitons and bands were determined. The first excitonic states are formed at Gamma-Y direction of Brillouin zone and have hole effective mass m(V1)* = 2.6m(0) and electron effective mass m(C1)* = 1.3m(0). The second excitonic states near X point in direction Gamma-X and the third excitonic states in U point of Brillouin zone are formed. Excitonic transitions in U point are allowed in both polarizations and effective mass of holes in U point (m(V1)* = 3.46m(0)) is more than one at Gamma-Y direction (m(V1)* = 2.6m(0)). Polarized transitions in reflection spectra of E parallel to b and E perpendicular to b polarizations in wide energy range of 1-6 eV were revealed. Optical functions (n, k, epsilon(1) and epsilon(2)) for polarizations E parallel to b and E perpendicular to b in the wide energy range by Kramers-Kronig relations were calculated.