Arrangement, Dopant Source, And Method For Making Solar Cells

Abstract

Disclosed is an arrangement, dopant source and method used in the fabrication of photocells that minimize handling of cell wafers and involve a single furnace step. First, dopant sources are created by depositing selected dopants onto both surfaces of source wafers. The concentration of dopant that is placed on the surface is relatively low so that the sources are starved sources. These sources are stacked with photocell wafers in alternating orientation in a furnace. Next, the temperature is raised and thermal diffusion takes place whereby the dopant leaves the source wafers and becomes diffused in a cell wafer creating the junctions necessary for photocells to operate. The concentration of dopant diffused into a single side of the cell wafer is proportional to the concentration placed on the respective dopant source facing the side of the cell wafer. Then, in the same thermal cycle, a layer of oxide is created by introducing oxygen into the furnace environment after sufficient diffusion has taken place. Finally, the cell wafers receive an anti-reflective coating and electrical contacts for the purpose of gathering electrical charge.