TY  - JOUR
AU  - A.I. Pogodin
AU  - I.O. Shender
AU  - M.M. Pop
AU  - M.J. Filep
AU  - T.O. Malakhovska
AU  - O.P. Kokhan
AU  - V.Yu. Izai
AU  - R. Mariychuk
TI  - Particularities of optical behavior of Ag 8 SiS 6 single crystal
T2  - Semiconductor Physics, Quantum Electronics & Optoelectronics
VL  - 27
IS  - 3
SP  - 280
EP  - 286
PY  - 2024
DO  - 10.15407/spqeo27.03.280
UR  - https://doi.org/10.15407/spqeo27.03.280
AB  - Ag8SiS6 single crystal was grown by directional crystallization from melt. A crystal sample was investigated by optical ellipsometry and spectroscopy. This sample had nonlinear spectral dependences of the refractive index n and the extinction coefficient k. The presence of a sharp maximum in the spectral dependence of the refractive index and a rather sharp decrease in the values of the extinction coefficient k at the wavelength of 780 nm were found. The behavior of the optical absorption edge of the Ag8SiS6 single crystal in the temperature range of 77…300 K was studied. An exponential dependence of the absorption coefficient α obeying the Urbach rule was observed at all the investigated temperatures. The optical pseudo-gap Eg* and the Urbach energy EU were calculated from the obtained experimental data. An increase in temperature of the Ag8SiS6 crystal was found to lead to a monotonic, almost linear decrease in Eg* (1.853…1.615 eV) and a monotonic nonlinear increase in EU (44.32…55.01 meV). The contributions of the temperature-independent (EU)X,C and temperature-dependent (EU)T components to the total Urbach energy EU for Ag8SiS6 were evaluated within the Einstein model.
KW  - argyrodite
KW  - single crystal
KW  - optical absorption edge
KW  - Urbach’s rule
ER  -