Atmospherically sintered copper-base alloy application film with self-assembled barrier layer on silicon substrate for silicon photovoltaics

Abstract In this paper, we show the first production of Cu-based electrode materials including self-assembled barrier layers which can prevent Cu-Si inter-diffusion during sintering and are expected to be applicable to crystalline Si photovoltaics. The characteristics of electrodes produced by mixed Cu-P/Sn pastes at various compositions were evaluated. Electrodes sintered in an atmospheric environment showed electrical resistivity of below 1 × 10 −4  Ω・cm. In addition, the formation of compounds such as Cu 3 Si at the Si surface was prevented with a Sn particle ratio ranging between 20 and 60 wt%. The structural analysis revealed that the electrode included not only a Cu-Sn IMCs network but also a self-assembled Sn-P-O glass phase between the Cu-Sn IMCs network and the Si substrate, capable of forming a barrier layer to prevent Cu-Si inter-diffusion. These results may enable the widespread use of atmospherically sintered Cu-based electrode for the mass production of next-generation crystalline Si solar cells. Subsequently, the manner in which the Sn-P-O glasses were formed was discussed using a thermos-dynamical approach.