Nonlinear Contacts of Conductors with Rough Surfaces

The sources of passive nonlinearities are examined in contact joints of rough conductors. The proposed model of the tunnelling current in MIM contact junctions is discussed in comparison with the Simmons and WKB models. It is shown that our model correlates well with WKB approximation when thickness of the thin insulating layer is commensurate with the lattice period. Mechanical deformations of the contact area are also quantified for a single and multiple junctions. The contact areas are evaluated at different stages of asperity compression, and the explicit expressions are presented for the two cases: (i) weak elastic deformations and (ii) strong plastic deformations of the flattened contact frustums. The thermal effect on the current density is assessed by comparison of the developed model with the WKB approximation. The performed simulations shows that the temperature variations weakly affect the contact resistivity of the contact junctions of rough conductors.