Large-signal model of 2DFETs: compact modeling of terminal charges and intrinsic capacitances

Abstract

We present a physics-based circuit-compatible model for double-gated two-dimensional semiconductor-based field-effect transistors, which provides explicit expressions for the drain current, terminal charges, and intrinsic capacitances. The drain current model is based on the drift-diffusion mechanism for the carrier transport and considers Fermi-Dirac statistics coupled with an appropriate field-effect approach. The terminal charge and intrinsic capacitance models are calculated adopting a Ward-Dutton linear charge partition scheme that guarantees charge conservation. It has been implemented in Verilog-A to make it compatible with standard circuit simulators. In order to benchmark the proposed modeling framework we also present experimental DC and high-frequency measurements of a purposely fabricated monolayer MoS 2 -FET showing excellent agreement between the model and the experiment and thus demonstrating the capabilities of the combined approach to predict the performance of 2DFETs.npj 2D Materials and Applications (2019) 3:47 ; https://doi.

Compact Modeling of pH-Sensitive FETs Based on 2-D Semiconductors

“…The work presented in this brief develops a comprehensive description of the 2D-ISFET operation by combining a verified compact model of 2D-semiconductor FETs (2DFETs) [11] with the modeling of the solid-liquid interface through the Site-Binding model and the Gouy-Chapman-Stern approach [12]. The compact model here proposed constitutes the first description of 2D-ISFETs for pH sensing that is compatible with standard technology computer-aided design (TCAD) tools employed for circuit simulation.…”

“…The source/drain electrodes are considered to be passivated, so that ions cannot be adsorbed by these metals. In addition, our model considers a trapped charge density in the semiconductor, Qit, computed as [11], [17]…”

“…where Nit is the effective density of trap states and -qVit is the shift of the effective trap energy level respect to the conduction/valence band. Then, the trap capacitance Cit can be calculated as [11]:…”

“…We can, eventually, find an expression to evaluate the net sheet density assuming a parabolic dispersion relationship and incorporating Fermi-Dirac statistics [11]:…”

“…Considering a drift-diffusion transport regime, the current of a 2D-ISFET can be accurately calculated as [11], [24]:…”