Estimation of redox potential of strained si by density functional theory calculation

The effect of lattice strain in strained Si wafer surfaces was investigated with the redox potential as an index parameter for the evaluation of the surface reactivity. The redox potential was calculated by density functional theory calculations. The Gibbs free energies of strained Si, Sio₂, H₂O, and H₂, which are components of the equation that represents the redox potential, were estimated from the calculated energies. The results suggested that the strain in the Si lattice shifts the redox potential in the negative direction, and the amount of shift was estimated to be approximately 10 mV when the degree of strain in Si was 3%. In addition, the Si HOMO energy, which was related to the redox potential, increased with the lattice strain, indicating that the increase in HOMO energy induces the potential shift and possibly the surface reactivity.