The authors demonstrate the formation of pn and nn(+) junctions based on silicon supersaturated with sulfur (up to 0.46 at. %) using a combination of ion implantation and pulsed laser melting. Silicon wafers were implanted at 200 keV S-32(+) to doses ranging from 1x10(15) to 1x10(16) ions/cm(2) and subsequently melted and resolidified by using a homogenized excimer laser pulse. Above a threshold laser fluence of similar to 1.4 J/cm(2), the process produces a single crystal supersaturated alloy, free of extended defects, with a sharp junction between the laser melted layer and the underlying substrate, located near the maximum penetration of the melt front. Hall effect measurements indicate that the laser melted layers are n doped with a free carrier density up to 8x10(18)/cm(3) that decreases by one-third upon postirradiation furnace annealing at 550 degrees C. Dark current-voltage measurements performed on these structures show good rectifying behavior. The photovoltaic characteristics of the junctions were enhanced by postirradiation annealing at 550-800 degrees C. These effects are attributed to the evolution of a population of point defects that survive the laser treatment. The influence of ion implantation dose, laser fluence, and annealing temperature on the properties of the junctions is also presented and discussed. (C) 2007 American Vacuum Society.