Polycrystalline silicon thin film solar cells prepared by PECVD-SPC

R. H. BUITRAGO; G. A. RISSO; M. CUTRERA; M. BATTIONI; L. DE BERNARDEZ; J. A. SCHMIDT; R. D. ARCE; R. R. KOROPECKI

INTERNATIONAL JOURNAL OF HYDROGEN ENERGY

Elsevier

Lugar: Amsterdam; Año: 2008 vol. 33 p. 3522 - 3525

0360-3199

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 mm of total thickness. Schott AF-37 glass is used as a substrate, for their ability to withstand temperatures of up to 800 ºC. The amorphous cell is subsequently annealed at gradual temperatures of 100 ºC to achieve dehydrogenation up to 650–700 ºC for 12 h 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 ºC, 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 mA 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.