Physics-Based Modeling and Validation of 2-D Schottky Barrier Field-Effect Transistors

In this work, we describe the charge transport in 2-D Schottky barrier field-effect transistors (SB-FETs) based on the carrier injection at the Schottky contacts. We first develop a numerical model for thermionic and field-emission processes of carrier injection that occur at a Schottky contact. The numerical model is then simplified to yield an analytic equation for current versus voltage (I-V) in the SB-FET. The lateral electric field at the junction, control-ling the carrier injection, is obtained by accurately modeling the electrostatics and the tunneling barrier width. Unlike previous SB-FET models that are valid for near-equilibrium conditions, this model is applicable for a broad bias range, as it incorporates the pertinent physics of thermionic, thermionic field-emission (TFE), and field-emission processes from a 3-D metal into a 2-D semiconductor. The I-V model is validated against the measurement data of two-, three-, and four-layer ambipolar MoTe2 SB-FETs fabricated in our laboratory, as well as the published data of unipolar 2-D SB-FETs using MoS2. Finally, the model's physics is tested rigorously by comparing model-generated data against TCAD simulation data.