Oxidation and tribopolymerization mechanisms of Pt₃Si(001) surface

Platinum sillicides are a class of material to replace pure metal when using on Micro- and Nano-electromechanical system (MEMS and NEMS) devices due to their high conductivity and low surface oxidation. MEMS and NEMS devices are small scale, non-volatile and low-power consuming; and hence, they are considered to be the future generation of computational devices. However, tribopolymer formed on electrode contact surfaces with adsorbed ambient molecules under mechanical stress could contaminate the device and obstruct the way of MEMS and NEMS for massive production. Here, we focused on Pt₃Si surface material and determined thermodynamically stable surface to be Pt₃Si(001) with Pt₂Si₂ as termination structure. Similar to experimental observation, the study of binding strength of oxygen shows that the matierial is inert to surface oxidation. Furthermore, the density functional theory calculation on surface reaction with applied normal stress demonstrates that partially oxidized Pt₃Si surface presents low tendency of tribobopolymer formation when using benzene gas as the initial contamination source. Our study has further proved that the Pt₃Si could be a promising material for MEMS and NEMS switching devices.