Wetting behavior and reaction mechanism of molten Si in contact with silica substrate

Abstract

The photovoltaic silicon ingot is currently grown in silica (SiO2) crucible. However, adhesion between Si ingot and SiO2 crucible occurred frequently, leading to cracking in Si ingot. To solve these problems, it is important to understand the Si/SiO2 interfacial wetting behavior and reaction mechanism at high temperature. In this paper, the sessile drop technology and microstructural analysis method were used to study the Si/SiO2 interfacial wetting behavior and reaction mechanism at high temperature. The results show that the contact angle of Si drop on SiO2 substrate is 83.5 ± 2°. The interfacial reaction occurs between Si melt and SiO2 substrate at high temperature, causing uneven surface of substrate with many grooves. The Si melt fills grooves at high temperature and expands during solidification, which results in interlock structure and adhesion at Si/SiO2 interface. Finally, adhesion and cracking phenomena are interpreted by analytical models.