G. A. Il’chuk

Photosensitivity of n-CdS/p-CdTe heterojunctions obtained by chemical surface deposition of CdS

A new technology of chemical surface deposition is developed, and thin CdS films (35–100 nm) on the p-CdTe substrates are obtained. Electrical and photoelectric properties of n-CdS/p-CdTe heterojunctions are studied, and it is shown that the developed method provides high efficiency of photoconversion in the range restricted by the CdTe and CdS band gaps. It is shown that the method of chemical surface deposition of CdS can be used in the design of thin-film n-CdS/p-CdTe.

Photosensitive structures based on single-crystal silicon and phthalocyanine CuPc: Fabrication and properties

Vacuum thermal deposition of phthalocyanine CuPc onto the surface of crystalline silicon and subsequent magnetron sputtering of ZnO:Al are used to form n-ZnO:Al-p-CuPc-n-Si photosensitive structures for the first time. The highest photosensitivity of these structures SUm≈20 V/W is attained if the ZnO side of the structure is illuminated and is observed in the photon-energy range 1–3.2 eV at T=300 K. An induced photopleochroism is observed if the linearly polarized light is incident obliquely on the ZnO side; the magnitude of the photopleochroism oscillates as a result of the interference of linearly polarized light in the ZnO film. It is concluded that the suggested structures have prospects for use in broadband photoconverters of natural light and in rapidly tunable photoanalyzers of linearly polarized light.

Fabrication and photoelectric properties of oxide/CdTe structures

A new technological process is proposed for forming an energy barrier in cadmium telluride crystals, and rectifying photosensitive anisotype and isotype structures are obtained. The photoelectric properties of the obtained structures and their dependence on the geometry of illumination with natural or linearly polarized light were investigated and are discussed. The new technology can be applied to the fabrication of different kinds of photoconversion structures based on cadmium telluride.

Photoelectric Properties of ZnO/CuPc/Si Structures

Abstractn-ZnO:Al/CuPc/n(p)-Si structures were formed using vacuum-evaporation deposition of copper phthalocyanine (CuPc) layers on the surface of n-and p-Si wafers with subsequent magnetron-sputtering deposition of ZnO:Al layers on the CuPc surface. It is shown that the structures obtained exhibit a high photosensitivity (∼80 V/W at T=300 K) in the spectral range 1.65–3.3 eV. The rectification factor and photovoltaic effect in these structures are discussed in relation to the properties of silicon substrates. It is concluded that the contact of phthalocyanine with diamond-like semiconductors (e.g., silicon) are promising for application in wide-band high-efficiency photovoltaic converters.

Electrochemical synthesis of thin CdS films

Thin cadmium sulfide (CdS) films have been electrochemically synthesized on metal substrates and the related photosensitive surface barrier structures have been obtained. The proposed method can be used in the technology of thin-film photoelectric converters with large areas.

Optoelectronic effects in semi-insulating CdTe single crystals and structures based on them

The authors describe a gas-transport reaction method they recently developed using the compounds NH4Cl (Br, I) as transport agents. Using this method, they were able to grow semiinsulating cadmium telluride single crystals with carrier concentrations p=108–1010 cm−3 at T=300 K. These crystals were used to fabricate In-CdTe surface-barrier structures with peak voltaic photosensitivities of ∼105 V/W. Their investigations of the emission properties of homogeneous crystals at T=77K and distinctive features of their photosensitivity spectra revealed that these material characteristics derive from the use of Cl, Br, and I as dopants. By illuminating their In-CdTe structures with linearly polarized light at oblique incidence, they generated induced photopleochroism, which was measured and used to determine the refraction index of the material, which is found to be n=2.8. The paper concludes with a discussion of how these structures can be used as photodetectors of natural and linearly polarized light.

Photoelectric cells based on n-Ox/n-InSe heterojunctions: fabrication and properties

Rectifying photosensitive n-Ox/n-InSe heterojunctions, where n-Ox is native oxide of InSe, are obtained by the thermal treatment of the n-InSe crystals in air. The spectra of the relative quantum efficiency of the originally obtained heterojunctions are investigated in natural and linearly polarized radiation. It is shown that the heterojunctions obtained manifest broad-band photosensitivity, and photopleochroism emerges under oblique incidence of the linearly polarized radiation. The nature of the photopleochroism revealed is discussed. It is concluded that the isotype Ox/InSe structures can be used as photoconverters of natural and linearly polarized radiation.

Fabrication and Photoelectric Properties of n-ZnO:Al/PdPc/p-Si Structures

Photosensitive n-ZnO:Al/PdPc/p-Si structures were fabricated by vacuum sublimation of palladium phthalocyanine with subsequent magnetron sputtering of ZnO:Al films on p-Si substrates. The current transport mechanisms and the photosensitivity of the structures obtained were investigated. It is shown that structures based on PdPc films are promising for photosensitive devices based on contacts between organic and inorganic semiconductors.

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.

Fabrication and photosensitivity of heterojunctions based on CuIn3Se5 crystals

Heterojunctions based on p-CuIn3Se5 crystals are fabricated by magnetron sputtering of an n-ZnO:Al target and by putting naturally cleaved n-GaSe thin wafers onto polished surfaces of p-CuIn3Se5 wafers. The current-voltage characteristics and mechanisms of current flow in the diodes under study are analyzed. The photovoltaic effect revealed in the fabricated structures is discussed. It is shown that the fabricated photosensitive heterojunctions are promising for the development of selective analyzers of linearly polarized radiation.