High volume processing of point contact solar cells

Point contact cells require a thin base, high bulk lifetime, low surface recombination velocities, effective light trapping, and effective heat sinking. The authors address some of these production issues in implementing a point contact cell process using standard, high-volume, semiconductor manufacturing equipment. Modifications to equipment and procedures are described which increase process yield and cell efficiency. A membrane wafer structure has been used successfully for large-volume processing of very thin cells. An optical confinement study shows that a random pyramid texture performs as well as or better than regular and inverted pyramids. This texture has contributed significant efficiency gains to these cells. Lifetime studies have aided in the development of a fabrication process with minimal lifetime degradation. Cells have been produced reaching an efficiency of 23.9% at 64.9 suns. Improvements are suggested which are expected to yield still higher efficiencies.