Optical properties of SbSi: Co and SbSeI: Co single crystals

Abstract

Single crystals of SbSI: Co and SbSeI: Co were prepared by the Bridgman technique. The optical absorption spectra of these single crystals were investigated in the wavelength range 500–2500 nm. We determined the optical energy gaps of these compounds, and identified the electric states of cobalt impurity in these single crystals. We observed the impurity absorption peaks at energies of 14000-4000 cm −1 range due to cobalt impurity. It can be explained that the impurity absorption peaks are attributed to the electronic transitions between the energy levels of cobalt ions, which are sited in tetrahedral ( T d ) symmetry of crystal lattice as Co 3+ and Co 2+ ions. The crystal field parameters Dq are given by 697 cm −1 for Co 3+ and 454 cm −1 for Co 2+ ions in SbSI: Co single crystals, and also 847 cm −1 for Co 3+ and 452 cm −1 Co 2+ ions in SbSeI: Co single crystals.