Electronic, dielectric properties and charge transfer in a TlGaS$_2$ : Nd$^{3+}$ single crystal at direct and alternating current

The band structure, density of states, and electronic properties of a 32-atomic supercell of a semiconductor compound TlGaS$_2$ containing neodymium are calculated. On the grown new single crystals of TlGaS$_2$ : Nd$^{3+}$ (0.3 mol% Nd$_2$S$_3$), experimental results on the physical properties have been obtained. The temperature (93–538 K) and frequency (5 $\cdot$ 10$^4$–3.5 $\cdot$ 10$^7$ Hz) dependences of the dc and ac conductivity and the frequency dispersion of the dielectric coefficients of TlGaS$_2$ : Nd$^{3+}$ single crystals have been studied. It was found that in TlGaS$_2$ : Nd$^{3+}$, in the entire studied frequency range, there are losses due to electrical conductivity, and the charge transfer has a hopping character. The parameters of localized states are estimated, such as the density of localized states near the Fermi level and their spread, the average hopping time and distance, and the concentration of deep traps responsible for the dc and ac conductivity in TlGaS$_2$ : Nd$^{3+}$.