Naseka Y. Defect formation in CdZnTe and polycrystalline diamond films

The thesis is aimed to optical investigation of the peculiarities of defect formation in the detector-grade materials CdZnTe and CVD diamond films, caused by the different technological processes and ionizing radiation. The main investigation methods are photoluminescence and Raman scattering. The testing of the detecting properties of CdZnTe and diamond films was carried out using the standard spectrometric tract. In the work the main types of defects in the studied materials induced by the varying in the growth parameters, doping, thermal treatments and irradiation with fast electrons and γ-quanta were determined. The dynamic of the interaction between the growth defects and defects caused by post-growth actions was ascertained. In particular the efficiency of the doping of the CdZnTe crystals with In and Ge atoms for the compensation of the growth and radiation-induced vacancy type defects was shown. It was ascertained that the effect of the vacancy type defects compensation depends on the concentration of the doping atoms. The dynamic of the interaction of the Ge atoms in Cd0.96Zn0.04Te:Ge crystals with radiation-induced VCd under the accumulation of irradiation dose until 500 kGy was obtained. It was shown that the main rearrangement of the defect-impurity composition of Cd0.96Zn0.04Te:Ge crystals takes place until the dose 100 kGy, which exceeds the corresponding threshold for undoped crystals, and is determined by the generation of the VCd, their ionization and substitution by the Ge atoms with the association in the complexes GeCdVCd. As the result of the investigation of defect formation in the CVD diamond films, caused by the technological peculiarities of their deposition the fact that the films consist of two components – basic diamond and non-diamond (composition of sp2 and sp3 phases) was obtained. Their volume fraction depends on the deposition parameters – substrate material, temperature, working gas and pressure. It was shown that the hydrogen substitution in the mixture CH4+H2 on the N2 and Ar causes the decrease in the size of the diamond grains down to nanometers, the increase in the volume fraction of sp2 carbon phase and the size of their clusters and the substantial decrease in the resistivity (until 10-1 Ohm×cm). The detectors manufactured on the basis on the highly-textured films have shown the high sensibility during registration of the α-particles.