Self aligned hydrogenated selective emitter for n-type solar cells

Selective emitter cell architectures are one avenue for increasing industrial solar cell efficiency. N-type cell based technology is also gaining considerable attention for the same purpose. This paper describes a novel, single step selective emitter process using atomic hydrogen to passivate boron acceptor impurities. Grid lines act as a mask to hydrogenation, which lowers the surface concentration of electrically active boron between grid lines. Using EDNA to model this complex emitter, it was shown that Jsc can be increased in the emitter by 0.94mA/cm² with a short, low temperature atomic hydrogen treatment. A hydrogenation system has been developed, and initial experimental results on aluminum doped polycrystalline thin films shows its effectiveness. Cell fabrication is being developed to test this process on fabricated solar cells to verify theoretical results. Special processing considerations are discussed.