Yavorskyi R. Structural, morphological and optical properties of thin-film heterostructures based on compounds II-VI.

In PhD thesis based on complex experimental studies and relevant theoretical calculations, the analysis of the influence of structural, morphological and optical properties of the upper ZnO layer, the "window layer" of CdS, the absorption layer of CdTe and their heterostructures on the efficiency of the photoelectric cell was performed.The methods of scanning electron and atomic force microscopy are used to analyze the surface morphology of CdS and CdTe thin films deposited on glass and (100) silicon substrates by open evaporation in vacuum. A series of samples was deposited by various technological parameters. ZnO thin films were deposited by laser pulse deposition on glass and silicon substrates.From the phase analysis by the EDS method it follows that the deposited films are characterized by a stoichiometric composition. In addition, based on the diffraction spectrum of CdTe/glass thin films, there is a slight shift of the diffraction peaks towards a smaller angle, which indicates that the CdTe layer is under compressive stress, because the calculated values of a0 = 6.500 Å and a0 = 6.497 Å exceed for a standard powder sample (6.481 Å). The stress developed in the thin film is double: internal and external. Internal stress can be caused by conditions prevailing during film deposition (substrate temperature, deposition rate, etc.), while external stress is determined by the difference in thermal expansion coefficients between the substrate and the thin film.