Efficient high-deposition-rate all-hot-wire hydrogenated amorphous silicon n-i-p solar cells

Efficient all-hot-wire chemical vapor deposition (HWCVD) hydrogenated amorphous silicon (a-Si:H) n-i-p solar cells have been demonstrated. Using HWCVD, we made the intrinsic layer deposited at 17-20 /spl Aring//s and the doped layers at 5-10 /spl Aring//s. An initial efficiency of 7.1% and a stable efficiency of 5.4% after 1000 hours of 1-sun light-soaking have been achieved on untextured stainless-steel (SS) substrate. This efficiency improvement results primarily from incorporating into the p/i interface about 60 /spl Aring/ of on-the-edge a-Si:H material grown just below the condition that would lead to the transition to microcrystallinity. We also optimize p-layers in solar cells by varying p-layer thickness, substrate temperature, trimethylboron gas flow rate, and chamber pressure. The cell's fill factor increases from 0.60 to 0.68, and the open-circuit voltage increases from 0.86 to 0.88 V. Recently, we improved the light-trapping by depositing the solar cell on textured Ag/ZnO-coated SS supplied by Uni-Solar, and we obtained an all-HWCVD record initial efficiency of 8.7%.