Optimization of tunneling current in ferroelectric tunnel FET using genetic algorithm

摘要

Tunnel field effect transistor (TFET) is a gate-controlled, quantum FET device, exhibiting band-to-band tunneling (BTBT) transport phenomena with lower sub-threshold swing (SS) than bulk MOSFET devices. Low ON-state current (I_(ON)) is an inherent problem with TFET devices. Various research groups are working to address the limitations due to low ON-state current and for performance improvement of the device. The work in this paper is an attempt to overcome the low switching current issue by using ferroelectric material (Fe), barium titanate (BaTiO_3) in conventional double gate TFET, having Si_(1-x)Ge_x/Si semiconductors configuration. In the proposed TFET device, the high-κ dielectric HfO2 is replaced by BaTiO_3, ferroelectric material (Fe) in the source region. The replacement of HfO_2 gate materials by BaTiO_3 Fe is found to improve I_(ON) (～order of 10~(-8) A/μm-to-10~(-5) A/μm). The FeDGTFET device shows-103 times improvement in I_(ON) with unaffected I_(OFF) (～ 10~(-20) A/μm). In circuit and system design figure of merit, optimization is a critical task for designers. The work in this paper is divided into three sections. Initially, two structures based on high-K, one with only high-K (HfO_2) DGTFET and the other one based on HfO_2 and ferroelectric material BaTiO_3 (FeDGTFET), are compared. Analysis of the electric parameters of the two structures shows the performance advantage of the structure based on the ferroelectric material. Next, a parametric study of the FeDGTFET structure is performed linking Silvaco Atlas with MAT-LAB to analyze the electrical parameters of FeDGTFET. Finally, an optimization technique called algorithm genetic 'AG' is employed to show enhancement in the I_(ON) current from 10~(-5) to 10~(-4)A/μm without affecting the I_(OFF).