Contact test structures where there is more than one non-metal layer, are significantly more complex to analyse compared to when there is only one such layer like active silicon on an insulating substrate. Here, we use analytical models for complex test structures in a two contact test structure and compare the results obtained with those from Finite Element Models (FEM) of the same test structures. The analytical models are based on the transmission line model and the tri-layer transmission line model in particular, and do not include vertical voltage drops except for the interfaces. The comparison shows that analytical models for tri-layer contacts to dual active layers agree well with FEM when the Specific Contact Resistances (SCR) of the contact interfaces is a significant part of the total resistance. Overall, there is a broad range of typical dual-layer-to-TLTLM contacts where the analytical model works. The insight (and quantifying) that the analytical model gives on the effect of the presence of the contact, on the distribution of current away from the contact is shown.

The electrical characteristics of Au/Ni/Ti/ n-SiC contacts have been examined as a function of implant dose (1013-1014 ions/cm2) at 5 KeV and temperature of annealing (750-1000 °C). Measurements of specific contact resistance, ρc, were approximately constant at lower implant doses until increasing at 1 x 1015 ions/cm2 for both C and P ions. Annealing at a temperature of 1000 °C has reduced the value of ρc by an order of magnitude to ∼1 x 10-6 Ω.cm2 at implant doses of 1013-1014 ions/cm2. Auger Electron Spectroscopy (AES) has shown that annealing at 1000 °C resulted in a strong indiffusion of the metallization layers at the interface.