Tl1−xIn1−xSnxSe2 (x = 0, 0.1, 0.2, 0.25) single-crystalline alloys as promising non-linear optical materials

Novel materials for the infrared two-photon absorption—Tl1−xIn1−xSnxSe2 single crystals (x = 0, 0.1, 0.2, 0.25) were grown. Their optoelectronic properties including two-photon absorption at wavelength equal to 9.4 μm at different temperatures were studied. From the spectral data it was established that band gap energy increases with increasing SnSe2 content in the solid solutions reaching its maximum for the largest content (x = 0.25). The infrared two photon absorption has achieved its maximal value at x = 0.1. The temperature dependence of the optical band gap at various compositions in the range of 77–300 К is practically linear. The band gap value decreases with the increase of T causing the spectral shift of the absorption edge to the low-energy region. Additionally X-ray photoelectron core-level spectra for pristine and Ar+-ion irradiated surfaces of Tl1−xIn1−xSnxSe2 single crystals have been measured.