Buchkovska M. Electronic properties of nanoscale thin film barrier and ohmic contacts for GaN and SiC wide-gap semiconductors.

Results of researches published in 20 scientific works are presented for the thesis defense purpose.The results of comprehensive research and study processes occurring in ohmic contact with the barrier and diffusion barriers based on nanostructured films TiB2 to SiC and GaN wide-gap semiconductors are presented in thesis. The dependence of thermal stability for barrier contact of Au-TiB2-n-6H SiC films vs parameters of TiB2 film were shown. The optimal nanocrystalites sizes and thermal stability of contacts electrophysical parameters after annealing at Т = 1000°С were determined. At contacts with Au-TiB2-n-GaN Schottky barrier on current-voltage characteristics at room temperature two distinctive areas where predominate field and thermoelectronic mechanism of current transport were detected. It was shown that current transport may be related to tunneling from the end of shunt dislocation, which crossing the space charge region. Self-diffusion of contacting layers and the structural continuity of TiB2 barrier layer at high-temperature processing and structural stability of Au TiB2 Ni-n-SiС and Au-TiB2-Al-Ti-n-GaN-i-Al2O3 at Т = 900°С of ohmic contacts were not detected. The dominant current transport mechanisms were established and contact resistivity was calculated. Degradation processes in LED chips based on GaN contacts were investigated. It was shown that main factor of degradation processes in ohmic contact at high temperatures was diffusion between contacting layers. For the first time, software for research of LED modules, depending on the parameters of the spread chips were developed.