A backside hydrogenation technique for defect passivation in silicon solar cells

Abstract

A novel technique is described for confinement of hydrogen in silicon solar cells during a high-temperature process. It is shown that hydrogen implanted at low energies on the backside of a solar cell can be confined within the cell through a metallization process consisting of deposition of aluminum and a subsequent alloying. The alloying of aluminum is done by a rapid optical processing technique. The passivation effects of hydrogen are identified in terms of improvements in the cell parameters of small area solar cells. It is shown that if the processing is done without the aluminum cap, the hydrogen is driven out of silicon with no passivation effects. This method can render hydrogen passivation compatible with standard solar cell process techniques.