Opanasyuk A. Structural, electrophysical and optical properties of II-VI compound thin films and their heterojunction

The thesis is devoted to research of the physical processes and effects related to real structure of the II-VI compound thin films and their heterojunction, optimization of the structural, optical and electrophysical properties one- and multilayer structures based on II-VI compound in order to development photoactive microelectronic devices with improved properties. For this purpose the complex analysis of the surface morphology, chemical composition, structural and substructural properties of the films depending on growth conditions was performed, also the influence of this parameters on optical and electrophysical, as well as point defects structure. As a result the growth conditions of the single-phase layers with good optical and structural properties, usable for devices manufacture has been determined. The method of injection spectroscopy which allow to obtain information about localized centers (LC) parameters in II-VI compound band-gap and related materials with narrow distribution of localized centers directly from the voltage-current characteristics (VCC) of the space charge limited current (SCLC) was developed. The influence of spatial inhomogeneity of the films along depth and with presence of near surface states at one or both interfaces on LC parameters determination accuracy has been studied. Also the calculations of corrective coefficients which allow taking into account spatial inhomogeneity of the material during traps parameters determination. With the help of the analysis of the VCC SCLC, -Т dependencies and low-temperature photoluminescence the (LC) parameters (depth energy and concentration) in films was determined and their identification was carried out. The ZnTe/CdTe and ZnS/CdTe heterojunctions (HJ) were obtained, and then the structural and electrophysical properties of these multilayer structures were investigated. Namely the current flow mechanisms and parameters which described these mechanisms were defined, also the band diagrams of the HJ was plotted.