Image Charge and Dipole Combination Model for the Schottky Barrier Tuning at the Dopant Segregated Metal/Semiconductor Interface

First-principle-based calculations are given to explain the Schottky barrier height (SBH) modifications of nickel silicide/silicon contacts by dopant atoms. Dopant atoms, including B, Al, In, Mg, P, As, Sb, and S, are placed near the NiSi₂/Si interface, and a systematic study of their effects on the band structure is considered. A new image charge and dipole combination model is proposed to explain the SBH tuning by these atoms, which is in good agreement with experimental observations. Both image charge and dipole moment provide the same p-SBH lowering direction for B atom and the same n-SBH lowering direction for Sb atom. Therefore, the total lowering of the SBH is enhanced for B and Sb; thus, they are good candidates for SBH modifications of nickel silicide/silicon contacts in CMOS applications.