Method of doping silicon, metal doped silicon, method of making solar cells, and solar cells

A low temperature process for forming a metal doped silicon layer in which an amorphous silicon layer is deposited onto a substrate at low temperatures, with a metal layer then deposited upon the silicon layer is described. This structure is then annealed at low temperatures to form a metal doped polycrystalline silicon having greater than about 1x10^20 dopant atoms per cubic cm of silicon