V. Yu. Rud

Physical properties of CuxAg1−xIn5S8 single crystals and related surface-barrier structures

The electrical properties and photoluminescence spectra of single crystals of the ternary compounds CuIn5S8, AgIn5S8 and their solid solutions have been investigated. We have determined the type of conductivity, the mobility, charge carrier concentrations and energies of the radiative transitions in these materials. We have fabricated surface-barrier structures from these single crystals and measured the voltaic photosensitivity.

Optical absorption and photosensitivity of CuInxGa1-xSe2 thin film structures

Thin polycrystalline films of CuInxGa1−xSe2 (0⩽x⩽1) were fabricated by pulsed laser evaporation. Results of measurements of the optical properties, photocurrent polarization indicatrices, and spectral dependence of the photoconversion quantum yield of In-p-CuInxGa1−xSe2 structures are discussed. A window effect in the photosensitivity has been observed, and it is concluded that it is possible to use CuInxGa1−xSe2 thin films as photoconverters of solar radiation.

Synthesis and characterization of n-ZnO:Al/CoPc/p-Si structures

Photosensitive structures of the n-ZnO:Al/CoPc/p-Si type were synthesized for the first time using vacuum sublimation of cobalt phthalocyanine (CoPc) and magnetron sputtering of a ZnO:Al target. The maximum photoresponse is observed when the structure is illuminated from the side of the ZnO layer and amounts to ≅400 V/W at T = 300 K. Mechanisms of current transfer and peculiarities of the photosensitivity spectrum are considered. It is suggested that the new photosensitive structures can be used in multiband photoconverters of natural radiation with a broad working spectral range.

Thin-film photosensitive structures based on a homoconjugated organosilicon polymer-copper phthalocyanine heterojunction

Rectifying photosensitive structures of the ITO/P(Si)/CuPc type have been synthesized based on a heterojunction between a homoconjugated organosilicon polymer P(Si) and copper phthalocyanine CuPc. The maximum voltage responsivity of the samples (∼1 V/W at T = 300 K) was observed when the structure was illuminated from the P(Si) side. In this illumination mode, thin-film photovoltaic converters based on the proposed heterojunction exhibit a fine structure in the photosensitivity spectrum. It is suggested that the new structures can be used as selective photosensors.

Photosensitive structures based on HgGa2S4 single crystals: Preparation and properties

Photosensitive structures based on n-HgGa2S4 single crystals were prepared and investigated. It was concluded that HgGa2S4 crystals are promising for the fabrication of photodetectors of natural and linearly polarized light in the short-wavelength spectral region.

Photosensitive point structures based on CuIn2m + 1Se3m + 2 crystals

Photosensitive point structures based on CuIn2m + 1Se3m + 2 (m = 0, 1, 2) single crystals have been obtained for the first time by means of electric-discharge welding (EDW). The stationary current-voltage characteristics and the photovoltaic properties of the structures based on CuInSe2, CuIn3Se5, and CuIn5Se8 ternary semiconductors have been studied, which show evidence for the rectification effect and photoconversion. The character of interband transitions is established and the bandgap width variation in this series of compounds is traced. It is concluded that EDW can be successfully used for the fabrication of photoconverters based on multicomponent semiconductors.

Effect of electron irradiation on the photopleochroism of ZnO/CdS/Cu(In,Ga)Se2 solar cells

The effect of irradiation with 1-MeV electrons to various doses on the photosensitivity of ZnO/CdS/Cu(In, Ga)Se2 solar cells and related CdS/Cu(In,Ga)Se2 and ZnO/Cu(In,Ga)Se2 heterostructures has been studied. Both the photoconversion efficiency and the coefficient of induced photopleochroism of ZnO/CdS/CIGS solar cells remained practically unchanged upon irradiation up to a total dose of 10−17 cm−2. It is suggested that the method of polarization photoelectric spectroscopy can be used for evaluating the effect of electron irradiation on the photosensitivity of semiconductor photoconverters.

Photoluminescence of II–IV–V2 and I–III–VI2 crystals passivated in a sulfide solution

An investigation was made to determine how chemical treatment of the surface of II–IV–V2 and I–III–VI2 semiconductor crystals (such as CdSiAs2, ZnSnP2, CuGaSe2, and r-AgInS2) using a solution of ammonium sulfide in tert-butyl alcohol influences their photoluminescence properties. It is shown that the photoluminescence intensity is enhanced substantially after treatment with the spectral profile and energy position of the band peaks remaining unchanged.

Photovoltaic effect in a p-type CuInSe2/green leaf heterojunction

Photosensitive p-type CuInSe2/green leaf heterojunctions are fabricated. The photocurrent polarization indicatrix, as well as the spectral dependences of the quantum efficiencies for photoconversion and of the natural photopleochroism of the heterojunctions, are measured. The polarization dependence of the photosensitivity suggests that the upper valence band in CuInSe2 is of type G7. A window effect is observed in the sensitivity ratio and these heterojunctions may find applications as photoconverters for the intensity and polarization of light.

Photoelectric properties of an electrolyte contact with a CuInSe2 thin film

We have studied the photoelectric properties of the potential barrier which arises at the interface between an electrolyte and thin n-CuInSe2 films deposited on glass by vacuum evaporation. Photoelectrochemical cells were used to observe the rectification and photosensitivity near the fundamental absorption of CuInSe2 for photon energies ħω>1 eV. It was found that there is a correspondence between the spectral dependence of the absorption and the photosensitivity of the cells, which indicates a constant quantum efficiency for the photoconversion process. We conclude with a discussion of the practical application of the potential barriers studied.