High-efficiency microcrystalline silicon solar cells on honeycomb textured substrates grown with high-rate VHF plasma-enhanced chemical vapor deposition

The potential of high-rate growth of high-quality microcrystalline silicon (mu c-Si:H) films for solar cell applications is investigated by very high frequency plasma-enhanced chemical vapor deposition (VHF-PECVD) under a high-pressure SiH4 depletion condition. It is found that the morphology of textured substrates plays an important role in not only light trapping but also mu c-Si:H film growth. A high conversion efficiency of 11.1% is attained in a substrate-type mu c-Si:H cell on a substrate with honeycomb textures, which has rounded concaves in a honeycomb arrangement with an appropriate period. It is also clarified that ZnO:B films grown by metal organic chemical vapor deposition (MOCVD) are beneficial in terms of carrier collection compared with the standard In2O3:Sn (ITO) film grown by sputtering. On the basis of these findings, a new world-record mu c-Si:H cell with a certified conversion efficiency of 11.8% is developed with a relatively high deposition rate of 1 nm/s. (C) 2015 The Japan Society of Applied Physics