Analytical Current Transport Modeling of Monolayer Molybdenum Disulfide-Based Dual Gate Tunnel Field Effect Transistor

In this paper, we present a current transport model of MoS2-based dual gate tunnel field effect transistor from both analytical and numerical techniques. In analytical modeling, two-dimensional (2D) model of potential distribution with its corresponding energy level for the hetero-junction has been solved and implemented with Landauer current transport mechanism. The output characteristics have been compared with the quantum mechanical solution obtained from non-equilibrium Green's function (NEGF) formalism. The sub-threshold slope (SS), obtained from analytical and NEGF methods are 10 mV/decade and 12.6 mV/decade with on/off current ratio of 10⁷ and 10⁶, respectively at VDS = 0.5 V. We have considered scattering mechanism into our calculation and have shown that carrier transportation for 20 nm channel length is diffusive. In addition, scattering reduces the on current by an order of magnitude, and resembles good agreement with the atomistic simulation. Lastly, mobility and ionized impurity concentration for our proposed structure have been calculated as 27.2 cm²/Vs and 1.17 × 10¹³/cm².

I. Introduction

The predominant Si-based MOSFET is facing fundamental limitations due to drain induced barrier lowering (DIBL), quantum tunneling of carriers from source to drain and excessive power dissipation due to lowest possible SS of 60 mV/decade [1]. To overcome these issues, several improvements in architecture have been proposed [2]–[5]. Though tunnel field-effect transistor (TFET) and negative capacitance FET (NCFET), to some extent, have addressed the low-power density problem and demonstrated low sub- threshold slope, its low on current and poor electrostatic control over the channel region remains an unsolved issue [6], [7]. Among the newly emerged two dimensional (2D) materials, graphene and phosphorene are not suitable for logic operation due to zero bandgap and instability in normal atmospheric conditions [8]–[10]. Transition metal dichalcogenide (TMDC) materials with their decent bandgap, higher effective mass in the direction of propagation, good carrier mobility, and thermal stability become an ideal candidate for the transistor technology [11]. Among the TMDC materials, monolayer MoS₂ is a direct bandgap (1.8 eV) material with a lattice constant of 3.16 Å and has a bond angle of 80.73° between molybdenum and sulfur atoms in its composition [12], [13].