Publication date: 30 April 2017
Source:Thin Solid Films, Volume 628
Author(s): He Zhang, Kazuyoshi Nakada, Makoto Konagai
Intrinsic amorphous silicon oxide (a-Si1 Ox :H) buffer layers were deposited on both sides of crystalline silicon (c-Si) wafers using plasma-enhanced chemical vapor deposition (PECVD) technique. The input gas flow ratio of carbon dioxide (CO2 ) to silane (SiH4 ) was varied in a wide range to study the passivation and structural properties of the a-Si1 Ox :H buffer layers. In this work, when the a-Si1 Ox :H layer was quite thick (>2 /SiH4 flow ratios, resulting in an exceptionally low surface recombination velocity (<2 /SiH4 flow ratio was either rather low (<2 /SiH4 ratios. Moreover, it was found that the epi-Si content could be gradually suppressed by slightly increasing the CO2 /SiH4 ratio without affecting passivation quality. When the a-Si1 Ox :H buffer layer thickness was kept at only a few nanometers as required by silicon heterojunction (SHJ) solar cells, the PECVD optimum condition (CO2 /SiH4 ratio) for buffer layers was revealed by applying the a-Si1 Ox :H buffer layers directly in a practical SHJ solar cell. We found that when the a-Si1 Ox :H buffer layer containing a certain amount (~V OC ) and a high fill factor (FF) were obtained at the same time. By contrast, at the emitter side of the solar cell, only the buffer layer without any epi-Si can be used to provide high-quality surface passivation for an excellent SHJ solar cell.
Source:Thin Solid Films, Volume 628
Author(s): He Zhang, Kazuyoshi Nakada, Makoto Konagai