No abstract

The method of long-wave spectroscopy made it possible to study the IR reflection spectra of layered single crystals β-Tl1-xCuxInS2 (0≤X≤0.015) in in the frequency range of 40-500 cm−1 and the temperature range of 84 ¸ 300 K. It was shown that partial substitution of thallium atoms with copper atoms leads to a decrease in the frequencies of the corresponding oscillations in the frequency range of 40-500 cm−1 and does not lead (at these concentrations) to local oscillations. It was found that solid solutions β-Tl1-xCuxInS2 (X=0 ÷ 0.015) exhibit the characteristic single-mode behavior. It was shown that partial substitution of thallium atoms with copper atoms in single crystals β-Tl1-xCuxInS2 (X = 0.005; 0.010; 0.015) weakens the ionic bond in Tl–S, as a result of which the frequencies of “internal” oscillations shift towards low temperatures.

The anisotropy of the refractive index and the electro-optical effect in Tl1-xCuxGaSe2(0≤X≤0/02) crystals were studied. Refractive indices were shown to rise as they approach their own absorption band. The electro-optical effect in TlGaSe2 crystals was studied. It was shown that the EO effect in the case where the light and external electric field are directed along the “C” axis within the studied electric fields (up to 5 kV / cm) is quadratic. The quadratic EO effect for TlGaSe2 equals 1.3 · 10−9 CGS units. It was found that when the electric field is directed perpendicular to the “C” axis and the light is directed along the “C” axis the EO effect is linear. The results of the EO measurements are consistent with the fact that the TlGaSe2 compounds crystallize in a monoclinic lattice, with the space group Cc, but at the same time the TlGaSe2 crystals have higher symmetry than Cc.

By the method of thermal oxidation of n-type CuInSe2 crystals, n - n+ structures with a maximum absolute current photosensitivity of up to 10 mA / W were obtained at low rectification and no-load photovoltage. The used modes of thermal oxidation led to the formation of n-type layers on the surface of the n-CuInSe2 plates, the resistivity of which is 2-2.5 times higher concerning the initial substance. Measurements of the stationary current-voltage characteristics have shown that the structures obtained have a slight rectification K. All the structures obtained exhibit photosensitivity, which dominates when illuminated from the side of the layer in the spectral region of about 1 eV. The optimization of the process can reveal the technological possibilities of a significant improvement in the rectifying properties of isotypic structures based on CuInSe2.