A thin emitter wrap-through solar cell and method for making a thin
emitter wrap-through solar cell. The cell preferably includes a silicon
wafer substrate having a thickness of less than 280 microns. The p-type
area on the back side of the cell is minimized, which maximizes the
collector area and reduces or eliminates stress due to passivation of the
p-type area, which is required for conventional solar cells. The
efficiency of the cell of the present invention peaks for a much smaller
thickness than that for conventional cells. Thus thin wafers of
inexpensive, lower quality silicon may be used without a significant
efficiency penalty, providing a large cost advantage over other solar
cell configurations. Vias through the substrate, which connect emitter
layers on the front and back surfaces of the substrate, may consist of
holes which are doped, or alternatively may be solid doped channels
formed by migration of a solvent, which preferably contains a dopant,
caused by a gradient-driven process.