The Effect of Aluminum Thickness on Solar Cell Performance

For crystalline silicon solar cells having an alloyed aluminum back contact, open‐circuit voltage increases with aluminum thickness. The increase is ascribed to the formation of a p + /p "high‐low" junction by liquid‐phase epitaxy, resulting in increased efficiency for the cell. With thick aluminum layers, the characteristics of the p + regrown region are in reasonable agreement with predictions based on the Al‐Si phase diagram. With thin aluminum layers the junction is nonideal, and the improvement in is much smaller. Pile‐up of metallic impurities at the aluminum/p + interface is attributed to rejection of these impurities during the silicon regrowth process.