A method of forming contacts for a back-contact solar cell, the method comprising: forming a thin dielectric layer on a substrate ; forming a polysilicon layer on the thin dielectric layer ; forming and patterning a solid-state p-type dopant source on the polysilicon layer , the patterning exposing regions of the polysilicon layer between a plurality of regions of the solid-state p-type dopant source; and forming an n-type dopant source layer over the exposed regions of the polysilicon layer and the plurality of regions of the solid-state p-type dopant source, the forming comprising at least partially driving dopants from the n-type dopant source layer into the exposed regions of the polysilicon layer to form a plurality of n-type dopant-containing polysilicon regions between the plurality of regions of the solid-state p-type dopant source , wherein forming the n-type dopant source layer further comprises at least partially driving dopants from the plurality of regions of the solid-state p-type dopant source into the polysilicon layer, characterized by loading the substrate in a reaction chamber and, without removing the substrate from the reaction chamber, performing both the forming of the n-type dopant source layer over the exposed regions of the polysilicon layer and the plurality of regions of the solid-state p-type dopant source and the at least partially driving of the dopants from the n-type dopant source layer into the exposed regions of the polysilicon layer to form the plurality of n-type dopant-containing polysilicon regions between the plurality of regions of the solid-state p-type dopant source ; removing the substrate from the reaction chamber ; and, subsequently, heating the substrate to provide a plurality of n-type doped polysilicon regions among a plurality of p-type doped polysilicon regions , wherein prior to the heating , removing the plurality of regions of the solid-state p-type dopant source and removing the n-type dopant source layer . forming a thin dielectric layer on a substrate ; forming a polysilicon layer on the thin dielectric layer ; forming and patterning a solid-state p-type dopant source on the polysilicon layer , the patterning exposing regions of the polysilicon layer between a plurality of regions of the solid-state p-type dopant source; and forming an n-type dopant source layer over the exposed regions of the polysilicon layer and the plurality of regions of the solid-state p-type dopant source, the forming comprising at least partially driving dopants from the n-type dopant source layer into the exposed regions of the polysilicon layer to form a plurality of n-type dopant-containing polysilicon regions between the plurality of regions of the solid-state p-type dopant source , wherein forming the n-type dopant source layer further comprises at least partially driving dopants from the plurality of regions of the solid-state p-type dopant source into the polysilicon layer, characterized by loading the substrate in a reaction chamber and, without removing the substrate from the reaction chamber, performing both the forming of the n-type dopant source layer over the exposed regions of the polysilicon layer and the plurality of regions of the solid-state p-type dopant source and the at least partially driving of the dopants from the n-type dopant source layer into the exposed regions of the polysilicon layer to form the plurality of n-type dopant-containing polysilicon regions between the plurality of regions of the solid-state p-type dopant source ; removing the substrate from the reaction chamber ; and, subsequently, heating the substrate to provide a plurality of n-type doped polysilicon regions among a plurality of p-type doped polysilicon regions , wherein prior to the heating , removing the plurality of regions of the solid-state p-type dopant source and removing the n-type dopant source layer . <EOS>