Spatial Uniformity of Large-Area Silicon Layers (43 Ã\x97 43 cm2) Grown by Convection-Assisted Chemical Vapor Deposition

Silicon layers have been grown by convection-assisted chemical vapor deposition (CoCVD) on assembled substrates with a rectangular area of 43 cmtimes43 cm. First cells have been produced from these epitaxially grown layers with efficiencies exceeding 11%. The layers were investigated with respect to layer thickness, dopant incorporation and uniformity within the deposited area. The experiments show that the spatial distribution of the Si-layer growth rate in vapor flow direction depends strongly on the tilt angle of the reactor. At an optimum angle, a variation of less than plusmn10% in layer thickness was obtained. Profiles of dopant incorporation correlate with growth rate profiles. The effect of a non-uniform absorber thickness on a typical photovoltaic device was calculated