Solar cell emitter region fabrication using substrate-level ion implantation

A method of fabricating a solar cell, the method comprising:

• forming a lightly doped region in a back surface of the semiconductor substrate by ion implantation, the lightly doped region of a first conductivity type of a first concentration, wherein the back surface is opposite a light-receiving surface of the semiconductor substrate;
• forming a first plurality of dopant regions of the first conductivity type of a second, higher, concentration by ion implantation, the first plurality of dopant regions overlapping with a first portion of the lightly doped region;
• forming a second plurality of dopant regions by ion implantation, the second plurality of dopant regions having a second conductivity type of a concentration higher than the first concentration, and the second plurality of dopant regions overlapping with a second portion of the lightly doped region and alternating with but not overlapping the first plurality of dopant regions;
• forming a tunneling dielectric layer on a light-receiving surface of the semiconductor substrate;
• forming a doped amorphous silicon layer on the tunneling dielectric layer on the light-receiving surface of the semiconductor substrate prior to the thermally annealing the semiconductor substrate;
• and
• crystallizing the doped amorphous silicon layer during the thermally annealing the semiconductor substrate to form a doped polycrystalline silicon layer on the light-receiving surface of the semiconductor substrate.