[20p-133-1~14] 16.3 Bulk, thin-film and other silicon-based solar cells

[20p-133-6] Effect of the microstructure of interfacial i-layers on the photovoltaic performance
in a-Si:H/c-Si heterojunction solar cells

〇Hitoshi Sai¹, Chen Po-Wei^1,2, Hsu Hung-Jung¹, Matsui Takuya¹, Shota Nunomura¹, Matsubara Koji¹ (1.AIST, 2.Natl. Chiao Tung U.)

Keywords:solar cell, silicon, amorphous silicon

The impact of intrinsic amorphous silicon bilayers in amorphous silicon/crystalline silicon (a-Si:H/c-Si) heterojunction solar cells is investigated. The microstructure factor R* of the interfacial a-Si:H layer, which is an index of the Si-H bond microstructure and determined by infrared absorption spectroscopy, is controlled in a wide range by varying the growth pressure and the power density in plasma-enhanced chemical vapor deposition (PECVD) process. Surface passivation at the a-Si:H/c-Si interface is significantly improved by using an intrinsic a-Si:H bilayer, i.e., a stack of an interfacial layer with a large R* and an additional dense layer, particularly after the deposition of an overlying p-type a-Si:H layer. Consequently, the conversion efficiency of a-Si:H/c-Si heterojunction solar cells is markedly increased. However, it is also revealed that such an interfacial layer causes some negative effects including the increase in the series resistance and the current loss at the front side, depending on the growth condition. This result indicates that the interfacial layer has a significant impact on both the majority and the minority carrier transport.