Decoupling the Roles of Thermionic and Field Emissions in Contact Resistance of Field Effect Transistors

In field-effect transistors, contact resistances which limit the efficiency of the charge injection and extraction at the metal-semiconductor interface, are mainly influenced by the Schottky barriers. On considering the non-constant injection field strength along the channel direction beneath the contact electrodes, a new contact resistance model incorporating both thermionic- and field-emission current simultaneously is proposed based on the transmission line theory, via solving nonlinear differential equation. This proposed model predicts the current distribution as a function of transverse distance beneath the electrodes, and reveals the respective contributions from thermionic- and field-emission portion of the total current. The model could well depict the experimental data from both organic molecular- and 2D material- based transistors at different characterization temperatures, and decouple the contributions from both processes.