Circuit Level Modeling of Electrically Doped Adenine–Thymine Nanotube Based Field Effect Transistor

Debarati Dey,Luqman Chuah Abdullah,Ferial Ghaemi,Debashis De,Ali Ahmadian

doi:10.1109/access.2019.2963225

Abstract

We investigate the gate-controlled, electrically doped tunnelling current in Adenine-Thymine heterojunction nanotube-based Field Effect Transistor (FET). This analytical model FET is designed by Density Functional Theory (DFT) and Non-Equilibrium Green's Function (NEGF) based First principle formalisms. It is demonstrated that Band to Band Tunnelling (BTBT) is possible in relaxed Adenine-Thymine heterostructure nanotube. The evaluation of BTBT tunnelling probability to estimate tunnelling current for only ±0.01V applied bias voltage is calculated using Wentzel-Kramers-Brillouin approximation. Electrical doping is introduced to eliminate the probability of fault generation. By keen observation on the shift of energy levels in the band structure, the availability of high transmission co-efficient peaks and current-voltage response we demonstrate the Schottky barrier nature for this geometrically pre-optimized bio-molecular FET. The doping concentration is varied from 0.0001V to 0.1V to achieve a substantially large amount of tunnelling current when the electronic temperature is kept at 300K. The E-k diagram or complex band structure of this heterostructure nanotube ensures its in-direct semi-conducting nature. This is a first attempt to present a circuit-level demonstration using this Adenine-Thymine nanotube-based bio-molecular FET and validate the obtained results with the existing approaches.

Highlights

The tunnel Field Effect Transistor (FET) (TFET) has been proved as a strong candidate for future generation low power application due to its low subthreshold slope
Band to Band Tunnelling (BTBT) probability through the bio-molecular channel has been investigated using Density Functional Theory (DFT) conjugated with Non-Equilibrium Green’s Function (NEGF) based First principle approach with the help of Atomistix Tool Kit-Virtual Nano Laboratory (ATK-VNL) software simulator package version 12.8.0
Additional metallic gate with a small di-electric layer is placed at the top of this bio-molecular nanotube to form the tunnel FET (TFET)

Summary

Introduction

The tunnel FET (TFET) has been proved as a strong candidate for future generation low power application due to its low subthreshold slope. Though Silicon does not achieve low subthreshold slope and sufficiently high ‘‘ON’’-state current due to its indirect energy bandgap, alternative channel materials for FET are being investigated [1], [2]. In the field of organic electronics, recently Carbon Nano Tube (CNT), Graphene nano-ribbon based FETs draw the attraction of the researchers [1], [3]–[5]. Due to high carrier mobility and zero-band gap, graphene nano-ribbon FET fails to prove itself in the field of transistor application [1], [6]. Considering Poisson’s solution the drain current of this bio-molecular TFET is being investigated at 300K electronic temperature. In case of electrical doping, a potential drop is to be created between the two terminals of a system or in this case the two terminals of electrodes by inducing two different and opposite potentials

Methods

Results

Conclusion