Interface bonding and failure mechanism of Ti(001)/Si(001) and TiO2(001)/Si(001) interfaces: A first–principles study

Peeling is the main technical obstacle for coating applications. The interfacial properties of the coating and substrate play a crucial role in the peeling. In this work, the work of adhesion, electronic structure, crystal orbital Hamilton population (COHP), and tensile strength of Ti(001)/Si(001) and TiO 2 (001)/Si(001) interfaces, where Ti alloy is oxidized, are investigated through first-principles calculations. Results show that the Ti(001)/Si(001) interface bonding is stronger than TiO 2 (001)/Si(001), because of its high adhesion work (3.56 J/m 2 > 1.56 J/m 2 ). The ratio of total COHP to the interface area of Ti(001)/Si(001) interface is higher than that of TiO 2 (001)/Si(001) interface (0.565 > 0.458), and the Ti(001)/Si(001) interface bonding is stronger. The fracture of the TiO 2 (001)/Si(001) interface occurs in TiO 2 near the interface during interfacial tension, and the fracture of Ti(001)/Si(001) interface occurs in the relatively soft Ti metal. The adhesion work at the fracture atomic layer is greater than that at the interface atomic layer (3.62 J/m 2 > 1.56 J/m 2 ) in the TiO 2 (001)/Si(001). The adhesion work can't fully indicate the interface bonding strength, and bonding strength is related to the atomic bond direction. The tensile strength is a good choice to indicate the bond strength. The oxidation of Ti weakens the interface bonding. The tensile strengths of Ti(001)/Si(001)and TiO 2 (001)/Si(001) are 19.93 and 18.75 GPa, respectively. The fracture of the two interfaces is inside the material rather than at the interface, and the adhesion work can't fully indicate the bonding strength.