Understanding the influence of Lu, La and Ga active elements on the bonding properties of Sn/SiO2 interfaces from first principle calculations

The active elements play key roles in the soldering of SiO2 glasses using Sn-based solders. In this study, the influence of Lu, La and Ga active atoms on the Sn/SiO2 interfacial bonding property is investigated by first principle calculation systematically. We built the beta-Sn(011)/SiO2(0001) interface with low lattice mismatch firstly, and different terminations or stacking sequences are considered. The Wad (work of adhesion) was calculated to evaluate the mechanical properties of the interface. The O-T interface with O bridge site has the largest Wad of 3.84 J/m(2). With the doping of Lu and La atoms at the interface, the Wad values of interfaces increase to 5.52 J/m(2) and 5.29 J/m(2). The negative values of Delta Gseg (heat of segregation) suggest that doping Lu and La atoms at the interface is stable in thermodynamics. While doping Ga is not stable in thermodynamics. The electronic structures were studied by the methods of charge density difference and partial density of states. The results show that the Lu-O and La-O bonds are all ionic-covalent bonds, but with more covalent composition comparing to the Sn-O bond. In conclusions, Lu and La active atoms can improve the bonding properties of the Sn/SiO2 interface.