Study on the Microstructure of Polycrystalline Silicon Films Treated with Line Shaped Electron Beam
Line shaped electron beam was used for the recrystallization of nanocrystalline silicon layer that had been deposited on the low cost borosilicate glass-substrate in this paper. Polycrystalline silicon films of a 20μm thickness, which are the base for a solar cell absorber, have been investigated. Tungstendisilicide (WSi2) was formed at the tungsten/silicon interface as well as grain boundaries of the silicon. WSi2 improved the wetting and adhesion of the silicon melt. The surface morphology of the film was strongly influenced by the recrystallization energy density applied. Low energy density resulted in non wetted WSi2/W areas due to the reaction between the silicon melt and the tungsten. With the increased energy, the capping layer become smooth and continuous due to the pinholes becomes fewer and smaller. Excess of the energy density led to larger voids in the capping layer, more WSi2/Si eutectic crystallites, a thinner tungsten layer, and a thicker tungstendisilicide layer.
Hyungsun Kim, Junichi Hojo and Soo Wohn Lee
L. Fu et al., "Study on the Microstructure of Polycrystalline Silicon Films Treated with Line Shaped Electron Beam", Materials Science Forum, Vols. 544-545, pp. 471-474, 2007