Analytic model for minority carrier effects in nanoscale Schottky contacts

We present an analytic model for the current-voltage (I-V) behavior for a nanoscale Schottky contact, emphasizing the role of minority carriers. The minority carriers give rise to a surface recombination current that can strongly dominate the majority current flow throughout the bias range. The I-V curve for the surface recombination current shows a weak rectifying behavior, which could be misinterpreted as large variations of ideality factor and effective barrier height. The model calculations show a good match with experimental I-V curves for nanoscale CoSi₂ epitaxial islands on Si(111) and for direct scanning tunnel microscope tip point contacts, for a range of island size, doping type, and surface Fermi level.