Design and Optimization of Germanium-Based Gate-Metal-Core Vertical Nanowire Tunnel FET.

Won Douk Jang,Young Jun Yoon,Jun Hyeok Jung,Jaewon Jang,Jin-Hyuk Bae,In Man Kang,Min Su Cho,Sang Ho Lee

doi:10.3390/mi10110749

Abstract

In this paper, a germanium-based gate-metal-core vertical nanowire tunnel field effect transistor (VNWTFET) has been designed and optimized using the technology computer-aided design (TCAD) simulation. In the proposed structure, by locating the gate-metal as a core of the nanowire, a more extensive band-to-band tunneling (BTBT) area can be achieved compared with the conventional core–shell VNWTFETs. The channel thickness (Tch), the gate-metal height (Hg), and the channel height (Hch) were considered as the design parameters for the optimization of device performances. The designed gate-metal-core VNWTFET exhibits outstanding performance, with an on-state current (Ion) of 80.9 μA/μm, off-state current (Ioff) of 1.09 × 10−12 A/μm, threshold voltage (Vt) of 0.21 V, and subthreshold swing (SS) of 42.8 mV/dec. Therefore, the proposed device was demonstrated to be a promising logic device for low-power applications.

Highlights

The power consumption of future transistors has become one of the most important problems in the semiconductor industry
As Tch gets thinner, Ion increases since the effective tunneling barrier width decreases
The electric field across the channel region gets stronger as Tch decreases, resulting in the enhancement of the gate controllability

Summary

Introduction

The power consumption of future transistors has become one of the most important problems in the semiconductor industry. When the positive VGS is applied, the energy bands in the channel region areview lowered and BTBT occurs at thegate-metal-core channel–sourceVNWTFET interfaces as Figure 1 shows the cross-sectional of the proposed. The channel thickness (Tch ) and the gate-metal height (Hg ) were considered as design variables for optimization processes because Tch and Hg determine the tunneling probability and current drivability. The proposed gate-metal-core structure has the advantage that it proposes a wider source–channel junction area (A = 2π × (Rg + Tox + Tch ) × Hg ). The bandgap narrowing model, doping dependent mobility model, and quantum effect were considered to estimate the device performances more accurately [26]. Confinement effect were considered to estimate the device performances more accurately [26]

Results and Discussion

Output with different different

Conclusions