A contact resistance extraction method of 2D-FET technologies without test structures

A $Y$ -function based method (YFM) is used here to extract the contact resistance $R_{\mathrm{c}}$ of different two-dimensional (2D) field-effect transistor (FET) technologies. The methodology relies on individual transfer characteristics, at a single drain-to-source voltage, of devices from a same technology with different channel lengths. In contrast to the widely used transfer length method where a global-back gated test structure is required, the YFM presented here can be applied to 2D-FETs regardless the gate architecture. This method does not require the fabrication of dedicated test structures and hence it can be a useful and immediate tool for device characterization and scaling studies. $R_{\mathrm{c}}$ is extracted here for graphene-, black phosphorus-, WS2 and MoS2-FETs using the proposed methodology and considering the mobility degradation coefficient in the underlying model. The extracted values are in good agreement with the ones obtained with other approaches. An accurate description of the experimental drain current and channel resistance is achieved by using the extracted parameters in the corresponding equation.