Ambipolar Current Suppression, Analog/RF and Linearity Performance Improvement of Dual Material Stacked Gate Oxide TFET with Dielectric Pocket

In this article, the impact of high-K and low-K dielectric pockets on DC, analog/RF, and linearity performance parameters of dual material stacked gate oxide-dielectric pocket-tunnel field-effect transistor (DMSGO-DP-TFET) is investigated. In this regard, a stacked gate oxide (SiO2 + HfO2) with workfunction engineering is taken into consideration to improve the ON-state current (ION ), and suppress the ambipolar current (Iamb). To further improve the performance of the device, a high-K dielectric pocket (HfO2) is used at the drain-channel interface to suppress the Iamb, and at the source-channel interface a low-K dielectric pocket is used to improve the ION and analog/RF performance. Moreover, length of stacked gate segments (L1, L2, L3), pocket height, and thickness are optimized to attain better ION /IOFF ratio, and suppress the Iamb which helps to achieve higher gain and design of analog/RF circuits. The DMSGO-DP-TFET outperforms the dual material control gate-dielectric pocket-TFET (DMCG-DP-TFET) with SiO2 gate oxide and shows increment in ION /IOFF (∼ 4.23 times), 84 % increment in transconductance (gm), 136 % increment in cut-off frequency (fT ), 126 % increment in gain-bandwidth-product (GBP), and better linearity performance parametrs such as gm2 ,gm3, VIP2, VIP3 and IIP3 making the proposed device useful for low power and radio frequency applications.

Dual Metal Triple-gate-dielectric (DM_TGD) Tunnel Field Effect Transistor: A Novel Structure for Future Energy Efficient Device

Background: Power reduction is a severe design concern for submicron logic circuits, which can be achieved by scaling the supply voltage. Modern Field Effect Transistor (FET) circuits require at least 60 mV of gate voltage for a better current drive at room temperature. The tunnel Field Effect Transistor (TFET) is a leading future device due to its steep subthreshold swing (SS), making its ideal device at a low power supply. Steep switching TFET can extend the supply voltage scaling with improved energy efficiency for digital and analog applications. These devices suffer from a sizeable ambipolar current, which cannot be reduced using Dual Metal Gate (DMG) alone. Gate dielectric materials play a crucial role in suppressing the ambipolar current. Objective: This paper presents a new structure known as triple-gate-dielectric (DM_TGD) TFET, which combines the dielectric and work function engineering to solve these problems. Method: The proposed structure uses DMG with three dielectric gate materials titanium oxide (TiO2), aluminum oxide (Al2O3), and silicon dioxide (SiO2). The high dielectric material alone as gate oxide increases the fringing fields, which results in higher gate capacitance. This structure has been simulated using 2-D ATLAS simulator in terms of drive current (Ion), ambipolar current (Iamb) and transconductance (gm). Results: The device offers better gm, lower SS, lower leakage and larger drive currents due to weaker insulating barriers at the tunneling junction. Also, higher effective dielectric constant gives better gate coupling and lower trap density. Conclusion: The proposed structure suppresses the ambipolar current and enhance the drive current with reduced SCEs.

Gate-on-drain overlapped L-shaped channel Tunnel FET as label-free biosensor

In this manuscript gate-on-drain L-shaped channel Tunnel FET is proposed to detect various biomolecules through label-free bio-sensing detection technique. Biomolecules can be detected in the proposed structure through modulating ambipolar current between channel and drain by overlapping gate on drain thus creating a cavity. Trapped biomolecules within cavity gets immobilized. Immobilized biomolecules change the drain to channel tunneling width, thus changing the ambiploar leakage current. Drain doping and cavity length was fine-tuned to achieve better sensitivity in terms of ambipolar current and ambipolar knee voltage shift with and without presence of biomolecules. A maximum sensitivity of 3.8×107 is achieved for drain doping of 5×1019 donors/cm3 and cavity length of 60nm. A high value of sensitivity is achieved for each biomolecules when drain doping ranged from 1019 donors/cm3 to 5×1019 donors/cm3 and cavity length ranged between 40nm to 50nm. Effect of differently charged biomolecules on sensitivity has also be structured.