Kostylyov V. The processes of photovoltaic energy conversion in silicon multilayer structures with a diffusion-field barriers.

Dissertation is devoted to solving the complex scientific problem - development of scientific principles creation of high efficiency solar cells (SC) and solar battery (SB) based upon multilayer structures with combined diffusion-field barriers. The thesis summarize the results of complex experimental and theoretical studies of photoelectric energy conversion processes in silicon multilayer structures with combined diffusion-field barriers. Is discussed the features of generation and recombination processes and collection of nonequilibrium charge carriers in silicon structures with surface diffusion-field barriers based on mono and polycrystalline silicon. Recombination processes in silicon structures with spatially nonuniform distribution of recombination centres is analyzed. The physical model of the SC is proposed and a computer simulation of photoelectric energy conversion is carried out. Are discussed exciton effects in crystalline silicon and their influence on the processes of photoelectric energy conversion. A new approach to analyze the mechanisms of influence of surface recombination on the process of collecting non-equilibrium charge carriers in silicon photosensitive structures with diffusion-field barriers is proposed. Experimentally shown that at formation of active n+ - regions in p-type silicon by means thermal diffusion of phosphorus occurs the effect of selfgettering, when the volume of silicon substrate is purified from generation-recombination complexes, while the deterioration of recombination parameters of n+-region occurs due to its contamination gettered fast diffused amount of impurities and defects. Is shown that formed at the same conditions silicon dioxide layers thermally grown on flat and textured surface of silicon significantly differ by impurity composition and microstructure of the transitional layer. Are proposed the physical principles of diffusion-field type SС creation. SС basic design is developed based on silicon wafers n- and p- conductivity type with a efficiency 20% (AM1, 5). Keywords: photovoltaic energy conversion, silicon, multilayer structures, diffusion-field barriers, texturing, recombination.