| Abstract [eng] |
The investigation of high density carrier dynamics in GaN, InGaN, and diamond samples with different defect density by light induced transient grating technique is presented in the thesis. The experimental studies on numerous samples, grown at different conditions, combined with extensive measurements in a wide range of carrier densities (1E16-1E20 cm-3) and temperature (9-300K) is used to identify the interplay of radiative and nonradiative recombination mechanisms, to determine carrier lifetime, diffusion coefficient, and diffusion length. It is shown that dislocation governed carrier recombination is a dominant recombination channel in GaN samples with dislocation density above 1E8 cm-2, otherwise, the bimolecular recombination dominates at high carrier densities. Experimentally observed increase of carrier diffusivity in GaN is caused by Fermi pressure at degenerate carrier plasma. The correlation between the carrier lifetime and concentration of nitrogen defects points out that nitrogen-related defects act as the main centers of nonradiative recombination in synthetic diamonds. A novel heterodyne detection scheme for LITG technique is presented. The heterodyning is achieved by coherently mixing the picosecond pulses of diffracted and scattered light. It is shown that a phase difference between theses fields can be controlled by moving holographic beam splitter along its grating vector. |
