Analytical modeling of transport phenomena in heterojunction triple metal gate all around tunneling field effect transistor

Marjana Mahdia,Quazi Deen Mohd Khosru

doi:10.1063/5.0024864

Abstract

An analytical model for the transport phenomena of a heterojunction triple metal gate all around tunneling field effect transistor (HTM GAA TFET) is developed for the first time in this paper. The continuous surface potential profile of the staggered-gap aligned heterojunction device is achieved by solving Poisson’s equation, and then, Kane’s model for band to band tunneling is used to derive the drain current of the device. The comparison between the modeling results and Technology Computer Aided Design (TCAD) simulation results with the GaAs0.5Sb0.5/In0.53Ga0.47As heterojunction stems satisfactory consistency. The robust and compatible model approaches the surface potential, electric field, band to band tunneling generation rate, and drain current in an HTM GAA TFET in a methodical manner. The influences of gate oxide thickness, gate oxide dielectric constant, and gate metal work functions on the performance of the considered device are also investigated. To achieve an impactful perspective, the subthreshold swing, Ion/Ioff ratio, and threshold voltage of the device are reviewed as well.

Highlights

Extreme scaling in MOSFETs has some negative effects such as high leakage current, high subthreshold swing (SS), and short channel effects
Ffermi is a correction factor to achieve the proper shape of the drain current of the device, and G is the band to band tunneling generation rate, and this rate is integrated over the effective tunneling volume of the device
The design of our device has been made in such a way that the lowest work function of the first metal allows more energy band bending at the source–channel junction, which revamps the band to band tunneling (BTBT); the highest work function of the second metal increases the hole carrier conduction; and the work function of the third metal decreases the ambipolarity phenomenon in the device, all of which result in high drive current in the Tunneling Field Effect Transistors (TFETs), as per Fig. 11

Summary

INTRODUCTION

Extreme scaling in MOSFETs has some negative effects such as high leakage current, high subthreshold swing (SS), and short channel effects. The SS in TFETs can be monitored by gate voltage and can be lowered down up to a great extent.[4] planar TFETs have some major drawbacks such as low oncurrent (Ion), corner effects, and short channel effects To overcome these shortcomings, Gate All Around (GAA) structures were proposed.[3,5,6,7,8] conventional TFETs suffer from many other disadvantages such as random dopant fluctuation, ambipolarity, and high parasitic capacitance.[9] Many techniques, i.e., drain work function engineering,[10] gate dielectric engineering,[11] Gaussian doping,[12] bandgap engineering,[13] and gate overlapping over the source/drain region,[14,15] are adopted to resolve these issues. A robust modeling of transport phenomena in a Heterojunction Triple Metal (HTM) GAA TFET is studied in this work as a promising addition to the existing literature. The study on the characteristics of the proposed device is further extended by inspecting the SS, Ion/Ioff ratio, and threshold voltage of the device

DEVICE STRUCTURE

Surface potential

Drain current

MODEL VALIDATION

CONCLUSION