Inhomogeneous ohmic contacts: Barrier height and contact area determination

The current-voltage characteristics at a uniform ohmic contact are, by definition, dominated by its series resistance and ordinarily offer little information, beyond an upper-bound, on the Schottky barrier height (SBH) of the metal-semiconductor junction. We demonstrate through temperature-dependent measurements of Au “ohmic” contacts on n-type Si(100)1 × 1-S, however, that quantitative information on not only the magnitude of the SBH, to within ± 0.03 eV, but also the effective conduction area can still be deduced. Details of these analyses, which require the use of a thin Si epi-layer, and the “partisan interlayer” mechanism, which lead to the formation of ohmic contacts, are discussed.