A computational study on interfacial doping and quantum transport of silicide-silicon contacts

In nanoscale silicon CMOS, the contact resistance could considerable lower the on-current and significantly increase the delay. Most models of metal-semiconductor and silicide-silicon contacts remain over-simplified and phenomenological. In this study, ab initio simulations based on the density-functional theory (DFT) and quantum transport simulations based on the non-equilibrium Green's function (NEGF) formalism have been developed to model and investigate the technologically important silicide-silicon contacts. The results indicate that in spite of the existence of a considerable metal-induced bandgap states, a carefully designed interfacial doping scheme can effectively modulate the Schottky barrier height (SBH). The modulation of the SBH can transform a rectifying I-V characteristic of a Schottky diode to a nearly linear I-V characteristic of an Ohmic contact even without changing the bulk semiconductor doping density.