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The authors have developed a simple, cheap and reproducible technology for obtaining thin-film heterostructures based on CdTe with a given surface morphology during vacuum deposition, which contributes to their low cost [1, 2]. The critical dimensions (thicknesses) of individual layers of the heterostructure were substantiated, a simulation was performed and a wide range of optical properties was investigated [3]. It is shown that for the deposited CdS / CdTe heterostructure on glass it is possible to obtain an efficiency of 15.8%. Given that thin films are relatively new systems, their study can offer much wider opportunities for technological improvement of photovoltaic energy converters. According to the analysis of modern literature data, the efficiency can be increased by performing deposition on ITO films and introducing nanoparticles of controlled sizes.

Thin films of CdTe were obtained by vapor phase condensation, namely by open vacuum evaporation, using different technological factors, in particular, different thickness (different time of deposition t) d = (540 -2835) nm, deposition temperature T v = 200°C and evaporator temperature T e (500 -600)°C. The films were deposited on silicon substrates. The morphology of thin film condensates is determined on the basis of ASM and SEM studies analysis. Were received dependences of avarage roughness and root mean square roughness from the material of substrate and film thickness. It was established that the growth of surface nanostructures is determined by Strankі-Krastanov mechanism.Кeywords: cadmium telluride, thin films, nanostructures, growth processes.Стаття поступила до редакції 15.09.2017; прийнята до друку 05.12.2017.

Fundamental and applied research on renewable energy is actively supported for the development of world science and maintaining the energy independence and security of different countries. This section analyzes the publications of scientists from two countries-Ukraine and Poland-in the field of "thermoelectricity," "photoelectricity," and "bioenergy" to find regularities in each state and to determine the prospects for joint research. Ukraine and Poland share a common border and have similar climatic conditions and historical heritage, but Poland is a member of the EU, and its legislation in the field of renewable energy complies with the regulations of the European Community. Ukraine is making every effort to develop renewable energy. Comparison of the state of research in these countries is also an example of the analysis of the situation at the borders of EU countries and may answer questions related to sustainable development, the mass transition to renewable energy, and the refusal to use fossil fuels and nuclear power plants. The analysis is based on the results of data published in the international scientific databases Web of Science and Scopus. The most advanced areas of research in each country are identified, analyzed, and aimed at practical application.

The paper presents the study of the optical properties of a thin layer of Cadmium Sulphide deposited on Cadmium Telluride films. CdTe thin films were obtained by vapor phase condensation method using different technological factors, in particular, different thickness (different time of deposition τ) on glass substrates. After deposition the optical properties were analysed by Swanepoel method, using transmission spectra. The upper thin layer of CdS was deposited by thermal evaporation method on CdTe thin films. The change in optical properties of CdS/CdTe heterojunction in comparison with CdTe thin films was investigated. Using a Swanepoel method were calculated the main optical constants, such as refractive index, absorption coefficient and optical conductivity. By this method the thickness of the thin film was determined and compared with the experimental values obtained by the profilometer.