Influence of tellurite glass on reaction between Si3N4 anti-reflection coating film and Ag paste for electrodes in Si solar cells

The reactivity of tellurite glass with Si3N4 was investigated using X-ray diffraction (XRD) analysis and was discussed in terms of basicity parameter, B, and the O1s binding energy, as a measure of the basicity of tellurite glasses. Through XRD analysis, it was revealed that tellurite glasses with a high basicity react significantly with Si3N4 to produce SiO2. Observation of a Ag electrode containing glass and the microstructure of a Si wafer by scanning electron microscopy (SEM) and scanning transmission electron microscopy (STEM) revealed that Ag paste containing highly reactive tellurite glass can effectively decompose the anti-reflection coating (ARC) composed of Si3N4. When glass with a high reactivity decomposed the ARC and the calcined Ag electrode contacts with the Si wafer, Ag/Te alloy particles were observed to precipitate from the tellurite glass phase at the interface between the Si wafer and Ag electrode. SEM and STEM observations also revealed that these Ag/Te alloy particles form a conductive path between the silicon wafer and Ag electrode.