A solution to the problem of the shortage of silicon feedstock used to grow multicrystalline ingots can be the production of a feedstock obtained by the direct purification of upgraded metallurgical silicon by means of a plasma torch. It is found that the dopant concentrations in the material manufactured following this metallurgical route are in the 10(17) cm(-3) range. Minority carrier diffusion lengths L-n are close to 35 mu m in the raw wafers and increases up to 120 mu m after the wafers go through the standard processing steps needed to make solar cells: phosphorus diffusion, aluminium-silicon alloying and hydrogenation by deposition of a hydrogen-rich silicon nitride layer followed by an annealing. L-n values are limited by the presence of residual metallic impurities, mainly slow diffusers like aluminium, and also by the high doping level. (C) 2008 Elsevier B.V. All rights reserved.