Optimum Parameters for Obtaining Polycrystalline Silicon for Photovoltaic Application

Abstract

The cost effective conversion of solar energy into electricity via solar cells remains an ongoing concern of researchers worldwide. The use of polysilicon has been suggested as a possible alternative to achieve this goal. The presence of traps in the grain boundaries having dangling bonds, however, limits the photovoltaic efficiency of solar cells synthesized from polysilicon. The present work constitutes search for optimal processing parameters for the development of polycrystalline silicon solar cells and their large scale manufacturing. The processing parameters depend essentially on the operating temperature, duration of the isothermal heating and the rate of growth of the polysilicon solar cell. These parameter in turn depends highly on the crystallographic states and purity of the material. The optimal processing parameters result in high nucleation rate followed by growth of the silicon grains. This process leads to the crystallization of polysilicon solar cells. In this study the processing parameters for the melting, crystallization and cooling have been optimized. The X-ray diffraction patterns of the samples show the presence of various crystalline phases. The study of crystal orientations by X-ray diffraction patterns shows the crystal orientation along (111), (110) and (100) planes. The (110) and (100) planes are present predominately on the material surface with an advantage for the (110) plane.