TFET Research Articles

Modeling of junctionless based dielectric modulated vertical TFET biosensor

This research article focuses on using a junctionless-based dielectric modulated vertical Tunnel FET (VTFET-DM-JL) as a biosensor. The objective is to detect biomolecules without the need for labeling, using electrical signals by modulating the dielectric constant. The JLFET, which is a device without any doping gradient or junction, serves as the structural foundation for this research. To understand the behavior of the structure, a potential model is created in this research which involves solving the Poisson equations (PE) under various boundary conditions. In addition, the incorporation of a high-K gate oxide improves the reliability of the device, particularly in terms of low power consumption. The paper explores the impact of dielectric constant values ranges from 1 to 12 by calculating figure of merit (FOM) values, including linearity, sensitivity, and noise assessment. As an example, Gelatin with a dielectric constant value of 12 exhibits a drain current sensitivity of 6.7 × 108, which is 9 % higher than apomyoglobin (κ = 8.1), 12 % higher than Bacteriophage-T7 (κ = 6.4), and 46 % higher than APTES (κ = 3.57) sensitivity, at a cavity length of 30 nm. Additionally, various FOMs, including linearity, sensitivity, and noise characteristics, are computed for the device across the dielectric constant range of 1–12. The simulated results obtained using the widely available Silvaco TCAD tool is compared with the modeled outcomes. A comprehensive assessment of the FOM standards establishes the promising nature of the proposed VTFET-DM-JL structure in terms of linearity and sensitivity.

A complementary ternary inverter based on the line tunneling field effect transistors

A novel line-tunneling field effect transistor (LTFET) incorporating a reversed p-i-n structure is introduced. The line-tunneling process provides high ION and low SS while the reversed p-i-n structure keeps the IOFF independent on the gate voltage. The inclusion of this mixed conduction mechanism renders the proposed device well-suited for designing complementary ternary logic based on the off-state current mechanism. The designed ternary inverter with low static power dissipation is suitable for the emerging neuromorphic applications where low power is extremely significant. In addition, the proposed device only involves two kinds of conventional Si and Ge materials. In comparison to other devices, such as nanowire or nanotube devices, the suggested planar device structure is notably simpler. Consequently, the device and the ternary inverter are easier to be fabricated and more compatible with the CMOS process platform.

Electrostatically Doped Junctionless Graphene Nanoribbon Tunnel Field-Effect Transistor for High-Performance Gas Sensing Applications: Leveraging Doping Gates for Multi-Gas Detection.

In this paper, a new junctionless graphene nanoribbon tunnel field-effect transistor (JLGNR TFET) is proposed as a multi-gas nanosensor. The nanosensor has been computationally assessed using a quantum simulation based on the self-consistent solutions of the mode space non-equilibrium Green's function (NEGF) formalism coupled with the Poisson's equation considering ballistic transport conditions. The proposed multi-gas nanosensor is endowed with two top gates ensuring both reservoirs' doping and multi-gas sensing. The investigations have included the IDS-VGS transfer characteristics, the gas-induced electrostatic modulations, subthreshold swing, and sensitivity. The order of change in drain current has been considered as a sensitivity metric. The underlying physics of the proposed JLGNR TFET-based multi-gas nanosensor has also been studied through the analysis of the band diagrams behavior and the energy-position-resolved current spectrum. It has been found that the gas-induced work function modulation of the source (drain) gate affects the n-type (p-type) conduction branch by modulating the band-to-band tunneling (BTBT) while the p-type (n-type) conduction branch still unaffected forming a kind of high selectivity from operating regime point of view. The high sensitivity has been recorded in subthermionic subthreshold swing (SS < 60 mV/dec) regime considering small gas-induced gate work function modulation. In addition, advanced simulations have been performed for the detection of two different types of gases separately and simultaneously, where high-performance has been recorded in terms of sensitivity, selectivity, and electrical behavior. The proposed detection approach, which is viable, innovative, simple, and efficient, can be applied using other types of junctionless tunneling field-effect transistors with emerging channel nanomaterials such as the transition metal dichalcogenides materials. The proposed JLGNRTFET-based multi-gas nanosensor is not limited to two specific gases but can also detect other gases by employing appropriate gate materials in terms of selectivity.

Assessment of the Biosensing Capabilities of SiGe Heterojunction Negative Capacitance-Vertical Tunnel Field-Effect Transistor.

In this study, a comparison of the negative capacitance vertical tunnel field-effect transistor (NC-VTFET) and VTFET for biosensing applications was conducted. Dielectrically modulated TFET demonstrates better sensitivity than the traditional metal oxide field effect transistor as a biosensor in label-free biosensing applications. The TFET biosensor, however, has much room for advancement by enhancing its DC characteristics. This research addresses the impact of ferroelectric gate oxide for integration of negative capacitance (NC) effect with the SiGe heterojunction pocket at the source-channel junction to enhance performance for biosensor applications. By putting the NC layer over SiO2, the channel voltage increases with decreased subthreshold slope and OFF current, thereby creating an NC effect. Because SiGe has a narrow band gap, pocket doping of SiGe near the source channel junction will increase the concentration of charge carriers, improving the band-to-band tunneling. In order to aid in the integration of biomolecules and to modulate band-to-band tunneling based on charge density (qf), dielectric constant (k), temperature, and cavity length, a cavity is additionally inserted above the source channel junction and underneath the NC layer, near to SiO2. These values were compared with and without the incorporation of NC layer with respect to various electrical properties such as drain current (Id), sensitivity, and electric field (E). According to the findings, labeled and label-free biosensors' sensitivity may be increased by incorporating the NC effect into VTFET biosensors.

Design and simulation of a germanium source dual‐metal dopingless tunnel FET as a label‐free biosensor

AbstractThis study presents a new dual‐metal dopingless tunnel field effect transistor with a Germanium source (GeS‐DM‐DLT) for label‐free biomolecule detection. Introducing a Ge source and dual‐metal gate provides improved drain current. We have considered an L‐shaped cavity at the top and bottom source metal region for investigating the sensitivity. The biosensor's sensitivity has been measured using the neutral biomolecules' dielectric constants (varying the k‐values in the cavity). The sensor's DC performance is investigated using transfer characteristics, BTBT rate, energy band, and electric field variation for different k‐values. The sensitivity performance of the proposed biosensor is evaluated in terms of different DC parameters (drain current, surface potential, subthreshold swing, interband tunneling rate, electric field) and RF parameters (parasitic capacitance, transconductance, cut‐off frequency, maximum frequency). The suggested biosensor offers a much‐improved SON of 9.86 × 108 and SRATIO of 1.94 × 104 for a dielectric constant of 22.0 at room temperature. Further research has been done to study the effects of dielectric materials, interface trap carriers (ITC), and temperature on drain current, drain current sensitivity, and other sensitivity parameters. The article also includes investigating the influence of the fill factor on sensitivity performance. The GeS‐DM‐DLT sensor performs best in fully‐filled conditions compared to the partially‐filled condition inside the cavity region.

An inverted T-shaped vertical tunneling InN/InxGa1-xN heterojunction TFET with high current ratio

An inverted T-shaped vertical InN/InGaN tunneling field effect transistor (TFET) with polarization-induced doping and high current ratio is proposed and investigated. An optimal structure of the proposed device is given by comparing on-state current, subthreshold voltage, and on-state/off-state current ratio. The polarization effect in III-N material induces electrons and holes in the source and drain regions, and non-physical doping can avoid random dopant fluctuations (RDFs) and high thermal budget. The InN/InGaN heterojunction TFET shows significant improvement over the homojunction TFET. The inverted T-shaped structure involves line and point tunneling simultaneously, so the proposed device can achieve higher on-state current than the conventional device. In addition, the proposed device shows the suppression of ambipolar current. The simulations reveal that the ION/IOFF of the proposed structure is about 6.91 × 1012. These results indicate that the line tunneling structure is still available in the polarization-induced InN/InGaN TFET.

Physics based model development of a double gate reverse T-shaped channel TFET including 1D and 2D band-to-band tunneling components

In this article, a Double gate reverse T-shaped channel tunnel field effect transistor (DG-RT-TFET) is mathematically modeled. The TFET has the potential for exhibiting various types of tunneling mechanisms. The modeled device encompasses both 1D and 2D Band-to-Band (BTBT) tunneling components, with each component developed in the epi-channel and channel, respectively. The study reveals that the 2D BTBT components exhibit greater dominance in the lower gate bias or subthreshold region, while the 1D BTBT becomes more prominent at higher gate bias voltages. By incorporating both models, a more comprehensive understanding of the DG-RT-TFET behavior can be achieved. To ensure the accuracy and reliability of the developed model, all model parameters are calibrated using the TCAD-sentaurus simulator. By comparing the results obtained from the developed model with the simulation results, it is concluded that the developed model for the DG-RT-TFET is suitable for capturing the device behavior and characteristics.

Catalytic Metal‐Gated Nano‐Sheet Field Effect Transistor and Nano‐Sheet Tunnel Field Effect Transistor Based Hydrogen Gas Sensor‐ A Design Perspective

AbstractIn this work, for the first time, the catalytic metal gate (CMG) based nanosheet Field Effect Transistor (NSFET) and nanosheet Tunnel Field Effect Transistor (NSTFET) are proposed for nano‐scale device dimensions, and the different design aspects of catalytic metal gate (CMG)‐based transduction for Hydrogen (H2) sensing are extensively investigated using numerical device simulation. The influence of applied biasing conditions and structural parameter specifications on the sensing performance of CMG‐NSFET and CMG‐NSTFET are methodically analyzed from device electrostatics and carrier transport mechanisms. Furthermore, the relative maximum sensitivity variations with H2‐partial pressure, ambient temperature, and the presence of ambient Oxygen are comprehensively studied. The study reveals that compared to CMG‐NSFET, the CMG‐NSTFET demonstrates a high immunity against bias and doping variations, with a notably higher (&gt; 50%) sensitivity within low H2 partial pressures (10−15 – 10−10 Torr). Next, the sensing performance of CMG‐NSTFET is systematically optimized through a band‐gap and gate‐stack engineering approach, leading to a 180% to 650% sensitivity improvement from lower (10−15 Torr) to higher (10−5 Torr) range of H2 partial pressure. Finally, the performance of optimized CMG‐NSFET and CMG‐NSTFET are extensively benchmarked against other reported nanostructured CMG‐FET and TFET‐based H2 gas sensors, exhibiting a notably higher sensitivity in the proposed sensors.

Influence of charge traps on charge plasma-germanium double-gate TFET for RF/Analog & low-power switching applications

The device reliability on account of charge traps at the Al2O3/Ge interface is a main distress for the Ge-based Tunnel Field Effect Transistor (TFET). Here, the influence of Interface Trap Charges (ITC) on the charge plasma-based Ge-Double-Gate TFET (CP-Ge-DGTFET) and conventional Ge-DGTFET's DC, Analog/RF, and linearity characteristics have been inspected using technology-computer-aided-design (TCAD) simulations for the donor (positive) and acceptor (negative) ITC. The charge plasma concept is adopted to induce excess carrier concentration within the source region on the integration of optimum work function metal electrodes. To recognize the impact of ITC, several figures of merits have been investigated, such as transfer characteristics, electric field, transconductance, cut-off frequency, parasitic capacitance, and linearity performance parameters (VIP2, VIP3, IIP3, and IMD3). The CP-Ge-DGTFET device structure revealed superior performance and reliability in comparison to Ge-DGTFET, even under the influence of ITC at the Al2O3/Ge interface. Therefore, the CP-Ge-DGTFET device structure is a sturdy contender for Analog/RF and low-power switching applications.

Review of: "The field-effect tunneling transistor nMOS, as an alternative to conventional CMOS by enabling the voltage supply (VDD) with ultra-low power consumption"

Review of: "The field-effect tunneling transistor nMOS, as an alternative to conventional CMOS by enabling the voltage supply (VDD) with ultra-low power consumption"

Toward Nanoscale Organic Tunnel Field-Effect Transistors with Small Subthreshold Swing and High On-State Current: A Computational Design Based on Two-Dimensional Covalent-Organic Frameworks

Toward Nanoscale Organic Tunnel Field-Effect Transistors with Small Subthreshold Swing and High On-State Current: A Computational Design Based on Two-Dimensional Covalent-Organic Frameworks

Review of: "The field-effect tunneling transistor nMOS, as an alternative to conventional CMOS by enabling the voltage supply (VDD) with ultra-low power consumption,"

Review of: "The field-effect tunneling transistor nMOS, as an alternative to conventional CMOS by enabling the voltage supply (VDD) with ultra-low power consumption,"

High Sensitivity of Dielectrically Modulated Tunnel Field Effect Transistor for Biosensor Applications.

The Dielectrically Modulated Full Gate Tunnel Field Effect Transistor (FET) with dual nanocavities, as described in the paper, is a novel device designed as a label-free biosensor for detecting cancer cell biomolecules. This biosensor utilizes the principles of field-effect transistors and incorporates nanocavities to enhance the detection sensitivity. The simulations are conducted using the Silvaco Atlas model, which allowed for the analysis of the device's electrical characteristics in the presence of various cancer cell biomolecules. The performance of the proposed device is evaluated using several sensing metrics, including current, threshold voltage, and subthreshold slope. These metrics are examined to assess their sensitivity to the presence of different cancer cell biomolecules. By analyzing these electrical characteristics, we can able to determine the device's ability to detect and differentiate between specific biomolecules associated with cancer cells. One important aspect discussed in the paper is the incorporation of nanocavities in the device design. These nanocavities have a significant impact on enhancing the sensing capabilities of the biosensor. The paper also introduces the concept of the filling factor parameter, which describes the fraction of the nanocavity volume occupied by the cancer cell biomolecules. This parameter plays a crucial role in achieving optimal sensing performance. Overall, the paper presents a comprehensive analysis of the proposed Dielectrically Modulated Full gate Tunnel FET embedded with dual nanocavities as a label-free biosensor for cancer cell biomolecules. The simulations conducted using the Silvaco Atlas model provide valuable insights into the device's electrical characteristics and its sensitivity to different biomolecules. The study emphasizes the significance of nanocavities and their filling factor parameter in achieving enhanced sensing performance for cancer cell detection.

Impact of Transport Mechanism on Binding Kinematics and Sensitivity of FET Biosensors

In this work, the impact of bioanalyte concentration and the dominant transport mechanism of biomolecules on the binding kinematics of the target biomolecules at the sensing surface have been investigated in detail. A comprehensive analysis of the fundamental parameters such as equilibrium response time and equilibrium density of the binding molecules at the sensing surface considering different concentrations of the analytes and their transport mechanisms has been performed. The impact of these realistic artifacts on the current sensitivity of emerging junctionless field effect transistors (JLFETs) and tunnel field effect transistors (TFETs)-based ion-sensitive field effect transistor (ISFET) has been investigated. Moreover, depending on the bioanalyte concentration, design guidelines for the dimensions of the sensing surface have been provided for a minimum limit of detection (LOD). The impact of charge screening and nonspecific binding on current sensitivity has also been discussed in depth. We believe that the guidelines presented in this work will enable the community to conceptualize, understand, and design novel label-free biosensors more rationally considering the practical scenario.

Design and Analysis of Charge Plasma-Based Heterogeneous L-Shaped Tunnel Field-Effect Transistor (TFET) for Low-Power Applications

Design and Analysis of Charge Plasma-Based Heterogeneous L-Shaped Tunnel Field-Effect Transistor (TFET) for Low-Power Applications

Surface-Potential-Based Drain Current Model of Gate-All-Around Tunneling FETs

Surface-Potential-Based Drain Current Model of Gate-All-Around Tunneling FETs

Design and Performance Analysis of Gate Overlap Dual Material Tunnel Field Effect Transistor

Design and Performance Analysis of Gate Overlap Dual Material Tunnel Field Effect Transistor

Gate Oxide Thickness and Drain Current Variation of Dual Gate Tunnel Field Effect Transistor

Gate Oxide Thickness and Drain Current Variation of Dual Gate Tunnel Field Effect Transistor

An Improved Structure and Analysis of Asymmetrical Spacer Nanowire Tunnel Field Effect Transistor

An Improved Structure and Analysis of Asymmetrical Spacer Nanowire Tunnel Field Effect Transistor

Accurate Analytical Modeling of Drain Current of Heterojunction Tunneling Field Effect Transistor

Accurate Analytical Modeling of Drain Current of Heterojunction Tunneling Field Effect Transistor