Preparation And Mechanism Analysis Of Crystalline Silicon Films With Preferred Orientation

With the emergence of energy and environmental problems,renewable energy,especially photovoltaic power generation technology,is increasingly valued,but the relatively high cost of photovoltaic power generation is a major obstacle to the large-scale popularization of photovoltaic power generation.In the cost of photovoltaic power generation,the price of solar cell module is a large part of it,and crystalline silicon thin film is a big development direction to reduce the price of solar cell.Compared with traditional crystalline silicon solar cells,it reduces the use of silicon materials and reduces the cost.Compared with the amorphous silicon thin film solar cell,it has no photoinduced attenuation effect,less defect states and higher photoelectric conversion efficiency.In the crystalline silicon thin film solar cell,the most important problem to be solved is the preparation of high quality polysilicon thin film.Our research goal is to prepare crystalline silicon thin films with high crystallinity and preferential orientation.In this paper,the thickness of crystalline silicon thin films prepared by experiments is determined according to the absorption coefficient of crystalline silicon materials to light and the diffusion length of small particles,and then combined with the deposition rate of magnetron sputtering instrument thin films.Then,graphite sheets were selected as the substrate material,and crystalline silicon thin films about 5.2 μm thick were prepared by magnetron sputtering technology,conventional thermal annealing technology and rapid thermal annealing technology.Besides,XRD,Raman,SEM and other characterization methods were used to analyze the preferred orientation,crystallinity and section morphology of the thin films.The main results are as follows:(1)according to the optical absorption coefficient of crystalline silicon material and the diffusion length of minority carriers,the optimal thickness of crystalline silicon thin film solar cell is calculated theoretically from 40 to 55 micrometers,which provides a reference for crystalline silicon thin film deposition.(2)the mechanism of preferred orientation of crystalline silicon thin films is described.During magnetron sputtering,if the substrate temperature is not high enough to cause heterogenic nucleation,grains with one or two preferred orientations will be produced only on the substrate and sedimentary surface.The following conventional thermal annealing treatment can promote the growth of fine grains.In this process,the growth rates of different crystal surfaces are different,so the crystal silicon thin films with preferred orientation can be obtained.(3)Crystalline silicon films with completely different preferred orientations were prepared on graphite plates and quartz glass substrates.Crystalline silicon thin films with Si(111)and Si(220)of totally different preferred orientation were prepared by using polished graphite plate as the substrate at 550℃ substrate temperature plus 600℃ annealing temperature and 700℃ substrate temperature plus 750℃ annealing temperature respectively.Crystal silicon thin films with Si(111)and Si(220)of totally different preferred orientation were prepared by using quartz glass as the substrate at 650℃ substrate temperature plus 650℃ annealing temperature and 750℃ substrate temperature plus 650℃ annealing temperature respectively.