Preparation Of Polycrystalline Silicon Thick Films And Analyses Of Their Properties

The energy crisis and environment problem increasingly prominent propelled the development of renewable energy, as a kind of clean, pollution-free, abundant new energy, solar energy is expected to replace traditional energy and become the mainstream of the energy in the future. Solar power mainly relies on the solar battery, Due to their high stability, low cost and relatively simple production process, polycrystalline silicon solar cell obtained the rapid development in recent years. In order to promote the large-scale application of the polysilicon batteries, people always study how to reduce the production cost of solar cells and improve the efficiency of the battery. Using cheap substrate and growing superior quality of polysilicon film become one of the most promising research directions on the preparation of high efficiency low cost solar cells.Based on the similar physical and chemical properties of graphite and silicon, in this paper, using polishing graphite flake as substrate material of the growth of polysilicon film. In order to reduce the negative impact of the lattice mismatch and the coefficient of thermal expansion mismatch between graphite substrate and the polycrystalline silicon film, this article introduced the polysilicon film seed layer as a transition layer, at the same time, the transition layer can be used as a barrier layer to stop the spread of the impurities in the graphite to the polysilicon film.In this paper, first of all, polysilicon film seed layer was fabricated by using the magnetron sputtering technology (MSC), rapid thermal annealing (RTA) on the polishing graphite flake, meantime, the best condition of the growth of seed layer was explored, then the polysilicon film was deposited on the seed layer via chemical vapor deposition (CVD), at last, the influence of experimental conditions on the preferred orientation and crystallinity was analyzed by theory, X-ray diffraction (XRD), scanning electron microscope (SEM) and microwave reflectance photoconductivity decay (u-PCD) was used in the characterization and analysis, Some of the main results and conclusions are as follows:1 polysilicon film seed layer was fabricated on the polishing graphite flake by using MSC and RTA, the best conditions for preparation of polycrystalline silicon thin film seed was obtained through a large number of experiment:sputtering time and temperature of 1000 ℃, respectively, annealing temperature of 850 ℃, and annealing time of 180 s, in which condition with high Si (220) preferred orientation of polycrystalline silicon thin film seed crystal layer was prepared on the polishing graphite substrate.2 the polycrystalline silicon film was deposited on the seed layer using CVD technique, SEM, XRD and u-PCD spectrum analysis showed that the high quality polycrystalline silicon film was gained, meanwhile, the introduction of polysilicon film seed layer is beneficial to the deposition of polycrystalline silicon film and the subsequent preparation of solar cells.3 The scherrer’s equation, the minimum energy principle, nucleation theory and mismatch degree formula were used to analysis the preferred orientation and crystallinity of polycrystalline silicon thin film seed layer and polysilicon film, Theoretical analysis was correspond with the experimental results.