Kidalov V. Heterojunctions on the basis of single-crystal and porous А2В6 and А3В5 structures obtained by radical beam epitaxy

Heterojunction on the basis of А3B5 (GaN/GaAs; GaN/por-GaAs) і А2B6 (ZnO/ZnSe; ZnO/ZnS:Mn). Scanining electron microscopre. X-ray diffraction, photoluminescence, This thesis dedicated to analysis of properties of heterojunctions on the basis of single-crystal and porous А2В6 and А3В5 structures obtained by radical - beam epitaxy. For reduction of stress in heterostructure GaN/GaAs it is offered to use porous substrates GaAs. The epitaxial layer GaN grown on the porous GaAs substrates is found to have no cracks on the surface. By results of a Raman spectroscopy, XRD measurements and analyses of spectra of a photoluminescence the stress GaN-films obtained on single-crystal (1GPa) and porous GaAs substrates (0,4 GPa) are determined. With the help of nitridation of porous GaAs (001) in nitrogen plasma thin films cubic - GaN were obtained. The conclusion was made that quality of the GaN films is dependent on the degree of porosity of the GaAs substrate. The samples of porous GaAs were fabricated by an electrochemical method on n- and p- type GaAs. Low-frequency Raman shift of the peaks, conditioned by the main optical phonons, in the Raman spectra of the porous GaAs was observed. Estimations of the size of nanocrystals in a porous GaAs by results of a Raman spectroscopy, photoluminescences and scanning electron microscopy are in a good agreement within the limits of 5-10 nm. In PL spectra porous GaAs layers both n- and p-type the broad peak in the region of 590-650 nm was observed, that bound with quantumsized effects as a result of formation of nanoobjects. The simulation of nitridation process of GaAs has allowed to establish technological conditions at which there is a full replacement of As atoms by atoms of azote in substrates GaAs and in surface area GaAs thin films of GaN are created. Depending on modes of radical-beam epitaxy the structures p-ZnO/n-ZnSe and p-ZnO/p-ZnSe/n-ZnSe are obtained. The photoluminescence of ZnO layers obtained by a method of radical-beam epitaxy is studied. The luminescence of Tm3+ in p- type ZnS and Er3+ in p- type ZnSe. The doping with rare - earth elements was performed by means of ion implantation in n-type materials. The post- implantation annealing of the radiation damages was performed in the atomic flux VI group elements. The interaction of such a flux with the treated crystal leads also to the inversion of the conductivity of these semiconductors to p-type. It was found that in both cases rare -earth elements occupy zinc sites. Doping with oxygen of ZnS:Mn films was performed by annealing at 673 -873 K in an atomic oxygen flow obtained by a HF discharge. The effect of such a doping on the electro optical, luminescent and photoelectrical characteristics of thin-film electroluminescent structures based on these films has been studied. The following changes in the films doped with O have been revelated from the obtained results: 1) the appearance at the upper interface of a thin ZnO layer and under it a ZnS1-x Ox layer with x < 0,013; 2) an increase of the concentration of Znvacancies and their complexes with donors in the bulk of the film; 3) the appearance of point oxygen defects and their complexes with other defects, e.g. with Mn2+ ions in the bulk.