Floating contact transmission line modelling: An improved method for ohmic contact resistance measurement

We propose an improved method, called floating contact transmission line modelling (FCTLM), for contact resistance measurement and the subsequent derivation of specific contact resistance ρc. Based on a set of floating contacts with different length between two large pads, the implementation of measurements is as simple as in the case of conventional TLM. Because floating contacts are not assumed to be equipotential, the method is applicable to a greater number of realistic situations. Finally, as a floating contact can be realized very short, it is possible to attain with an excellent precision the contact parameters, even in the case of very small transfer length (LT). In this work, floating contacts as short as 0.25 μm have been realized to characterize the non-diffusive Pt/Ti/Pt/Au contact on p+GaAsSb, allowing for consistent and accurate measurements of both transfer length and semiconductor sheet resistance beneath the contacts.