Vlasiuk V. Photoelectric processes in photosensitive silicon structures with surface passivated

The thesis examines the processes of photoelectric energy conversion in silicon photosensitive structures with passivated surface. The paper summarizes the results of complex experimental and theoretical research of the peculiarities of the photoconversion in photosensitive silicon structures with passivated surface. The peculiarities of the processes of generation, recombination and collection of nonequilibrium charge carriers in these structures are considered. The bulk and surface recombination processes and their influence on the photoconversion efficiency of are analyzed. Investigated on the decrease of surface recombination losses in photosensitive silicon structures by formation of heterojunctions on silicon. Experimental data on the influence of the creation of heterojunctions ІТО/Si, n-ZnO/Si, р-ZnO/Si, SiC/Si on the surface recombination velocity are obtained. Calculation of the recombination velocity in the space charge region (SQR) is performed in the assumption that the recombination in the SQR is determined by one deep level, the calculations of its dependence on Shockley-Reed-Hall lifetime, which is realized in SQR. The magnitude of the values Shockley-Reed-Hall lifetime in SQR was determined and its comparison with the lifetime in the quasineutral base region was determined. The latter was from measurements of the spectral dependencies of the short-circuit current. The characteristics of deep centers that determine the recombination velocity in the SQR are estimated, in particular, the their energy position, the concentration and cross sections of the capture of electrons and holes by these centers. Found non-radiative recombination parameter was equal 8,2∙1015 см-3. The influence of the exiton non-radiative recombination in silicon on the main photoelectric parameters of silicon solar cell, namely, the open circuit voltage, the fill factor and the photoconversion efficiency in the case of large and in the case of small values Shockley-Reed-Hall lifetimes is investigated. The contribution of exciton effects to the internal quantum yield of luminescence in silicon is analyzed. It was taken into account as a positive effect associated with the presence of radiative exciton recombination, as well as the negative, caused by the contribution of non-radiation exciton recombination. The dependences of internal quantum yield of luminescence in silicon of the levels of doping and excitation levels, as well as on the rate of surface recombination at room temperature have been analyzed. It is shown that at Shockley-Reed-Hall lifetimes > 1 ms, the positive effect is dominant, and at <1 ms - negative.