Polycrystalline silicon thin film solar cells prepared by PECVD-SPC

Among the most promising technological alternatives for the development of photovoltaic modules and cells of a low cost, good energetic conversion and feasibility for mass production, polycrystalline silicon thin film solar cells deposited directly on a transparent substrate are currently being considered the best. We have developed in our laboratory a PECVD reactor capable of producing the deposition of amorphous hydrogenated silicon at rates of above 2 nm/seg, allowing a significant production per line on the plant. Discharge gas is silane, to which diborane or phosphine is added so as to form the cell. Basically, work is done on a structure of cell type TCO/n+/p-/p+/M, which has 2 mu m of total thickness. Schott AF-37 glass is used as a substrate, for their ability to withstand temperatures of up to 800 degrees C. The amorphous cell is subsequently annealed at gradual temperatures of 100 degrees C to achieve dehydrogenation up to 650-700 degrees C for 12h until their complete crystallization is achieved. Our results show a complete crystallization of silicon with a grain size of less than a micron, with a dehydrogenation process at 500 degrees C, leaving a remainder of less than 1% in hydrogen as monohydrate. The parameters of the cell estimated from the IV curve yield low values, FF<0.55, Icc <200 mu A and Voc<420mV. The high series resistance is due to the grain size and defect density, which will be attempted to be improved by post-hydrogenation and rapid thermal annealing (RTA) methods at high temperatures. (C) 2008 International Association for Hydrogen Energy. Published by Elsevier Ltd. All rights reserved.