Detailed characterization and critical discussion of series resistance in graphene-metal contacts

We apply the contact–end resistance method to TLM structures in order to characterize the graphene–metal contact resistance. A critical analysis of the experimental results shows that the commonly used transmission line model fails to accurately describe the graphene–metal contact under specific biasing conditions. The experiments suggest the presence of an additional resistance contribution associated to the p–p+ junction induced in the graphene in the proximity of the contact. This voltage dependent resistance limits the range of applicability of the extraction technique. However, for carefully chosen bias conditions that reduce this additional resistance to small values, the technique provides reliable results, useful to investigate the graphene–metal contact properties and their technology dependence.