Schottky Barrier Height Modulation By Atomic Dipoles At The Silicide/Silicon Interface

We studied the behavior of boron (B) atoms around the nickel silicide (NiSi)/silicon (Si) interface through first-principles calculations. We found that B atoms, absorbed at the most stable substitutional sites on the Si side along the interface, dramatically reduce the Schottky barrier height (SBH) for a hole owing to atomic-scale electric dipoles generated between the ionized B atom and the induced image charge in the NiSi layer. We also found that this interface dipole generation leads to an increase of several orders of magnitude in the B solubility limit around the interface, enhancing SBH modulation. The possibility of interface atomic dipoles reducing the SBH was verified by both the observed B profiles and the measured I-V characteristics of the B-implanted NiSi/Si Schottky diodes.