Photoelectrical properties and the electronic structure of Tl1−xIn1−xSnxSe2 (x = 0, 0.1, 0.2, 0.25) single crystalline alloys

Photoelectrical properties of Tl1−xIn1−xSnxSe2 single crystalline alloys (x = 0, 0.1, 0.2, 0.25) grown using the Bridgman–Stockbarger method were studied. The temperature dependence of electrical and photoconductivity for the Tl1−xIn1−xSnxSe2 single crystals was explored. It has been established that photosensitivity of the Tl1−xIn1−xSnxSe2 single crystals increases with x. The spectral distribution of photocurrent in the wavelength spectral range 400–1000 nm has been investigated at various temperatures. Photoconductivity increases in all the studied crystals with temperature. Therefore, thermal activation of photoconductivity is caused by re-charging of the photoactive centers as the samples are heated. Based on our investigations, a model of center re-charging is proposed that explains the observed phenomena. X-ray photoelectron valence-band spectra for pristine and Ar+-ion irradiated surfaces of the Tl1−xIn1−xSnxSe2 single crystals have been measured. These results reveal that the Tl1−xIn1−xSnxSe2 single-crystal surface is sensitive to the Ar+ ion irradiation that induced structural modification in the top surface layers. Comparison on a common energy scale of the X-ray emission Se Kβ2 bands representing energy distribution of the Se 4p-like states and the X-ray photoelectron valence-band spectra was done.