Compact analytical model for monolayer transition metal dichalcogenide channel field effect transistors

Abstract

In recent years, researchers have been very excited about the prospects of 2-D transition metal dichalcogenides (TMD) as a suitable semiconducting material for the channel in transistor devices. In order to evaluate their suitability in next generation transistors, it is important to understand their device level performance. A rigorous analytical model can play a significant role in this regard. In this work we have developed an analytical compact model for monolayer 2-D TMD channel MOSFETs that can replicate device performance in all regions of operation. In order to better understand the effects of monolayer TMD, we have developed two models, one for the subthreshold region and the other for the inversion region. The subthreshold model is centered around the scale length of the device. At first, an analytical expression for the scale length was derived from the eigenvalue equation. It was important to make sure that the derived expression of scale length precisely incorporates all the device and physical parameters. Gauss’s law was applied in an infinitely small enclosure in the 2D channel which established a second order differential equation that governs the operation in 2D TMD FET. Channel potential and 2D carrier density was derived from the solution of this equation. Finally, the channel potential was used in the drift-diffusion equation to obtain an all-region closed-form solution for the drain current. Non-idealities were incorporated in this model by modifying intrinsic device parameters. We verified the applicability of our model by comparing our results with that of established numerical simulators and experimental reports. Our model properly replicated device performance for both long and short channel devices. Appropriate results were produced using this model for channel length as low as 10 nm.