Double Gate Tunnel FET Research Articles

Pocketed dual metal gate TFET: Design and simulation

In this work, design and simulation of two novel tunnel field effect transistors with improved DC and radio frequency (RF) performance has been conducted. The first proposed tunnel field effect transistor (TFET) employs a highly doped n + pocket in the intrinsic channel along with a combination of stacked oxide (silicon dioxide and hafnium oxide). This configuration helps in the enhancement of tunneling at the source/channel junction, thereby improving parameters like ON-current (ION), average subthreshold slope (SS avg) and ION/IOFF. The structure is modified further by employing a dual metal gate, having different work-functions, in addition to dual stacked oxide. The gate near the source, called as the tunneling gate, has a work function of 4.3 eV and a gate near the drain side, called as the auxiliary gate, has a work-function of 4.7 eV. This second proposed structure with dual metal gate and dual oxide offers significantly improved performance with on-current (ION) of ∼3 orders more than the conventional Double Gate (DG) Tunnel FET and a sub-threshold slope of 31 mV/dec. An ION of 2.7 × 10−5 A/ µm and an OFF current (IOFF) of ∼10−16 A/ µm is achieved in the second proposed device. The AC analysis has revealed that the cutoff frequency (fT) of the second proposed device is 1055 × higher than the conventional DG-TFET. Further, an increase of 3 orders of magnitude is achieved in the gain-bandwidth (GBW) product in the second proposed device in comparison to the conventional DG-TFET.

Optical FOMs of extended-source DG–TFET photodetector in the visible range of the spectrum

In this paper, the optical characteristics of an extended-source double-gate tunnel field-effect transistor (ESDG–TFET)–based photodetector in the visible range of the spectrum at wavelength λ = (300–700) nm are investigated. The optical characteristics are examined at three specific wavelengths λ= 300, 500, and 700 nm at an intensity of 0.7 W cm−2. The optical characteristics of photosensors, such as absorption rate, generation rate, energy band profiles, transfer characteristics, sensitivity (S n), quantum efficiency (η), signal-to-noise ratio (SNR), and detectivity, are extracted according to the incident wavelength of light. The results reveal that the ESDG–TFET-based photosensor exhibits better optical characteristics at λ = 300 nm compared to at λ = 500 and 700 nm. Moreover, the proposed photosensor provides sensitivity, SNR, and responsivity in the order of 91.2, 79 (dB), and 0.74 (A Watt−1), respectively, at λ = 300 nm. Due to the high incident optical energy (E g) at 300 nm, the absorption and emission rates of this photosensor are significantly larger; consequently, it reports better optical characteristics. Finally, a comparative study of the proposed TFET-based photosensor with photosensors cited in the literature is summarized in tabular form. A comparison study in terms of spectral sensitivity between single-gate and double-gate ESDG–TFET is also reported. Moreover, an inverter circuit based on ESDG–TFET is designed, and the corresponding transient analysis is highlighted under both dark and light states.

Sensitivity and Stability Analysis of Double-Gate Graphene Nanoribbon Vertical Tunnel FET for Different Gas Sensing

Sensing and detecting gases are crucial from the application point of view. The essential condition for present-time gas sensors is light, compact, less power dissipation, highly sensitive, thermally stable, and a good selection regards several gases. Due to the significant potential and modulation of the energy bandgap, two-dimensional material has recently attracted researchers attention. Graphene nanoribbon (GNR) is one of the candidates from the two-D material; it is extracted from the strip of one-dimensional graphene material, which can be a suitable contender for gas sensing devices. Therefore, in this work, the detailed investigation of the gas sensor of various gas has been reported by employing two-dimensional material-based DG-GNR VTFET as a sensor. Different gases, including Oxygen, Ammonia as well as Hydrogen gas, have been scrutinized for sensitivity and stability in several temperature ranges. In the present work, several catalytic metals are utilized in the gate electrode of the proposed device architecture for the different gas sensing applications. The intrinsic physics of the proposed gas sensor has been carried out in detail in the factor of different gas molecules and gas pressure. Finally, the temperature parameter varies to analyze the stability of the proposed device sensor within 200 K–400 K.

Optimization for Device Figure of Merit of Ferroelectric Tunnel FET using Genetic Algorithm

Tunnel FET is a gate-controlled, field effect transistor, followed band to band tunneling (BTBT) transport of charge carriers, having low subthreshold swing (SS < 60 Mv decade−1|T = 300 K). With tunnel FET, low-ION is a built-in problem, that limits its universal adaptability high-speed low-power uses. To overcome, this limitation of tunnel FET, a conventional double gate TFET has acquired for analysis having ferroelectric (BaTiO3)/HfO2 gate materials and source/channel region with Si1−xGex/Si semiconductor channel composition.The present device design techniques enhanced the ION and put down the subthreshold swing(SS). The analysis results by using the Silvaco simulator shows improvement in switching current(ION) approximately ∼103 times better than conventional DGTFET,without affecting the IOFF. Ultimately the change in ION∼order of 10−8 A μm−1 to 10−5 A μ has been measured for VDS ∼ 0.5 V at room temperature. The IOFF ( ∼10−20 A μm−1) has been measured. In addition to this, first time genetic algorithm has been used for the optimization of ferroelectric tunnel FET (Fe-Tunnel FET) device design parameters like a subthreshold swing (SS), ambipolar current (Iamb) and IONby using device deign parameters, doping (NS, ND), dielectric (εOX) and work function (WF).The research conclusion shows that Fe-Tunnel can play in lead backgroundfor super low power applications in advanced VLSI circuit and system.

Numerical assessment of dielectrically-modulated short- double-gate PNPN TFET-based label-free biosensor

A comprehensive investigation of dielectrically modulated Ge-source short double-gate PNPN tunnel FET (SG-PNPN TFET) based label-free biosensor is presented. Short gates and counter-doped pockets in the SG-PNPN TFET architecture improve band-to-band tunneling, which subsequently raises the device's drain current sensitivity. On the source side of the device, a nanocavity is created between the gate and the SiO2 layer. The sensing performance of the device was evaluated using the effect of the dielectric constant and charge density of the biomolecules. The non-ideal performance of the biosensor can be understood by analyzing the consequences of steric hindrance and irregular probe placement. The concave profile has the highest value of sensitivity among all the non-uniform profiles considered (including ascending, descending, concave, and convex). The sensitivity comparison of the proposed TFET biosensor with other FET-based biosensors revealed that the SG-PNPN TFET could function admirably as a low-power biosensor with improved sensitivity.

Modeling and Performance Analysis of a Split-Gate T-Shape Channel DM DPDG-TFET Label-Free Biosensor

This article proposes, for the first time, a split-gate T-shape channel dielectrically modulated (DM) double-gate TFET (DGTFET) with a drain pocket (DP). This device can be used as a label-free biosensor. The analytical model for DM DPDG-TFET has been developed and it has been validated against commercial simulation software (Silvaco TCAD). This article intends to focus both on the sensitivity of the biosensor and its performance as a tunnel field-effect transistor (TFET) device. This has been accomplished by improvisations in the channel shape. The performance of the device has thoroughly been investigated in terms of threshold voltage, subthreshold slope, ON current, and OFF current. Due to the novel design, the proposed TFET possesses higher sensitivity, higher <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${I}_{ {\text{ON}}}/{I}_{ {\text{OFF}}}$ </tex-math></inline-formula> current ratio, and lower subthreshold slope. The inclusion of DP at the drain–channel junction proves to be a successful way to remove the ambipolarity completely. The high ON current without any ambipolarity has been achieved by optimizing the DP length and its doping concentration. The proposed T-shape DM DPDGTFET proves itself to be superior to several reported devices in terms of both biosensor as well as field-effect transistor (FET) device. The presence and absence of charge of various biomolecules are taken into consideration for evaluation of device sensitivity as a label-free biosensor.

A new analytical modelling of 10 nm negative capacitance-double gate TFET with improved cross talk and miller effects in digital circuit applications

In this paper, the workability of a Negative Capacitance (NC)-Double Gate (DG) Tunnel FET (NC-DGTFET) for digital logic circuit implementation has been detailed. New analytical modelling of the drain current of the NC-DGTEFT considering the band to band tunneling (BTBT), Band tail tunneling (BTT) and Source drain tunneling (SDT) have been investigated. Significant IOÑ0.025 μA/μm at 250 mV and SS∼12mv/dec - 22mv/dec with very low IOFF (∼fA/μm) is observed with the optimized device. SILVACO ATLAS and MATLAB have been used to validate the proposed model. The modeled NC-DGTFET based Inverter, NAND/NOR has been implemented and the power, delay propagation, and the power delay product (PDP) of the circuit have been analyzed to show the energy efficacy of the NC-DGTFET in the sub-threshold regime (STR) with respect to baseline TFET (B-TFET). To evaluate the impact of the Miller's effects on the digital performances, NC-DGTFET-based five stages Inverter with Fanout = 1 is considered a device under test (DUT) here. Peak overshoot voltage and delay for different fanout and ferroelectric thickness are detailed to show the efficacy of the proposed logic circuits in sub-threshold regime. Both the cross talk and the Miller effects are mitigated significantly in the NC-DGTFET-based digital circuits.

Dependence of RF/analog and linearity parameters on ferroelectric layer thickness in ferroelectric tunnel junction dual material double gate (FTJ-DMDG) TFET

In this article, we have proposed a ferroelectric tunnel junction (FTJ) dual material double gate (DMDG) TFET using TCAD simulator, where a ferroelectric (FE) layer is incorporated at tunnel junction to increase the band to band tunnelling rate. TCAD simulation result reflects that the inclusion of FE layer leads to improved ON current with enhanced BTBT rate as the thickness of FE layer (t FE) is reduced from 4 to 2 nm. The RF/analog parameter like transconductance (g m), gain (g m/g d), cut off frequency (f t), transconductance generation factor (TGP), gain frequency product (GFP), and transconductance frequency product (TFP) are improved by noticeable amount with down scaling in t FE value. The linearity analysis like g m2, g m3, voltage intercept points (VIP2 and VIP3), power intercept point (IIP3), and 1-dB compression point are also highlighted in FTJ-DMDG-TFET by varying t FE. A noticeable improvement in linearity behaviour is perceived with increased value in t FE.

Dielectrically Modulated III-V Compound Semiconductor Based Pocket Doped Tunnel FET for Label Free Biosensing Applications.

In this paper, a novel structure of double gate tunnel FET has been proposed and simulated for biosensing applications. The device uses III-V compound semiconductors and an n+ doped pocket at the source channel junction. Biomolecules of different dielectric constants (K) with different charge densities (Nbio), both negative and positive, are inserted in the nano-gap cavities (15 nm ×1.5 nm) that have been created under gates near source channel junction to capture biomolecules. From extensive 2D simulations, ION sensitivity of 4.351 ×108/1.03 ×108/1.514 ×109 , subthreshold swing sensitivity of 15.67/20.21/18.57 mV/dec, and threshold voltage sensitivity of 18/12/23 mV for neutral (K = 12)/negatively charged biomolecules ( [Formula: see text] C/cm2, K = 12)/positively charged biomolecules ( [Formula: see text] C/cm2, K = 12) respectively has been observed. Also, transconductance sensitivity of 9.74 ×107 and ION/IOFF sensitivity of 5.255 ×108 for neutral biomolecules (K = 12) has been calculated. Furthermore, the device performance with one-third filled cavities, two-third filled cavities and fully filled cavities has also been studied. The performance of the proposed biosensor has been compared with the previously published work and it has been observed that the sensitivity of the proposed biosensor is 100 times better than the best reported biosensor.

Qualitative Analysis of DG-TFET Structures with Gate Material Engineering

The paper largely focuses on enhancing device parameters of a Double Gate Tunnel Field Effect Transistor structure such as ON current, OFF Current,transconductance and ratio of ON current to OFF current (ION / IOFF) using hetero dielectric gate material. The paper presents three state of art of dual gate TFET i.e., Conventional Double Gate TFET (CDGTFET), horizontally placed Dual Material Double Gate TFET (HDMDGTFET), vertically placed Dual Material Double Gate TFET (VDMDGTFET). The dual material dielectric combinations used in the structures are (SiO2-TiO2), (HfO2-TiO2) and (SiO2-SiC). The Structures are being modeled using Silvaco Atlas tool. Simulations of these structures are carried out and various electrical parameters have been obtained. The results obtained from simulation of these structures are being presented and discussed in this paper. Comparison of the three structures is carried out and resulted in the reduction of ON Current and OFF Current is observed.

Design and Performance Assessment of Split Gate Dielectric Modulated Junction less TFET Variation of Hfo2 by the Divided Gate Insulator for High Sensitivity Using Tcad Simulation

A number of more recent discoveries in microbiology have made reliable identification of nano-biomolecules and extensive analyses of them necessary. A variety of proteins, including DNA, biotin-streptavidin, amino acids, as well as many types of bacteria and viruses, must be found and analyzed in order to fully comprehend any odd behavior occurring inside of live cells. Rapid testing and detection are essential steps in preventing undiscovered biohazards from eradicating the human race and other terrestrial living things. Since many decades ago, developing an accurate, affordable biosensor has been a struggle for scientists [1]. When compared to pricey laboratory-based sensors and detection methods, FET-based lab-on-chip nano biosensors appear to be a promising substitute. It is significantly more dependable than conventional bulk sensors because of its size, affordability, low power consumption, resilience, faster response time, and better sensitivity [1]. Due to their precision, adaptability, and compatibility with embedded systems, dielectrically modulated FET biosensors with Nano cavities are emerging as a promising research area that can yield useful data on bio-analyses. As an alternative to conventionally doped TFET devices, using a charge plasma SiGe-heterojunction double gate TFET, a label-free biosensor can be produced, bypassing the need for conventional semiconductors, which require a large thermal budget and are susceptible to random dopant fluctuations (RDFs). The effect of changing the dielectric constant (k), the positive and negative charge density, the gate work function, and the cavity size has been investigated to better understand how these factors affect the performance of the proposed biosensor. These parameters modify the biosensor's electric characteristics, improving detection [2]. There is also discussion of how these factors influence the device's drain current, electric field, surface potential, sub-threshold swing (SS), insulator-to-metal film (ION/IOFF) ratio, and electron tunneling rate (ETR). The sensitivity of the drain current in the proposed biosensor is also investigated. There is no restriction on whether or whether the proposed structure is used for charged or neutral molecules.Under lower supply voltages, it is discovered that the SG-DM current JLFET's sensitivity is high, measuring 1.2 *10^3, with a potential sensitivity of 1.4 V. A result, the SG-DM [2] JLFET exhibits good application potential while consuming little power and having ahigh sensitivity.

Vertical GaN/InGaN/GaN heterostructure tunnel field-effect transistor: DC and analog/RF performance

This work reports an [Formula: see text]-type GaN/InGaN/GaN heterostructure vertical double-gate tunnel field-effect transistor (VTFET) using exhaustive calibrated simulation for the first time. Investigation has been done for the proposed structure by including a polarization layer of InGaN near the source-channel junction. From the analysis, it has been observed that after the introduction of polarization layer near the source-channel interface, drain current increases due to the increase in charge concentration (2DEG) near the interface due to inter-band tunneling. Value of 2DEG concentration achieved post introducing the polarization layer is [Formula: see text] [Formula: see text]. The reported structure is optimized using parametric sweep optimization technique. Here, a detailed dc and analog/RF performance estimation has been done for the structure with heterostructure. In-depth sensitivity analysis has been done for the structure with the polarization layer. It is reported that the structure with HfO2 as the dielectric material with [Formula: see text] of 2 nm and with gate metal work function of 5.8 eV gives the optimum performance at 300 K. Further, it demonstrates high cutoff frequency ([Formula: see text] and gain bandwidth product (GBW) as 1000 GHz and 300 GHz, respectively. Hence, the reported structure is a better alternative for high-power steep switching analog and RF applications.

Analysis on electrical parameters including temperature and interface trap charges in gate overlap Ge source step shape double gate TFET

In this paper, the electrical parameters are evaluated for the variations of temperature in Gate Overlap Ge source Step Shape Double Gate TFET (GO-Ge-SSDG-TFET) under the impact of interface trap charges (ITCs). Here, the effect of positive ITC (PITC) and negative ITC (NITC) with wide variation in trap concentrations along with variation in temperature (200–500 K) on DC, RF/analog, and linearity behavior are studied using TCAD simulator. It is found that there is up-gradation (degradation) in current ratio (ION/IOFF, ION/IAMBP), cut-off frequency (ft), and linearity parameters with PITC (NITC). At low gate voltage, there is degradation in OFF-state behavior with increased temperature and this is due to exponential dependence of temperature with Shockley-Read-Hall (SRH) recombination. Moreover, at high gate bias, Band to Band tunneling (BTBT) is dominant, which is weak temperature dependence and leads to negligible variation in drain current. The OFF state current is degraded by the order of 109 as temperature is increased from 200 to 500 K. At high temperature, the up-gradation in ft and intrinsic delay (τ) indicates improvement in device characteristic.

Electrical noise in Ge-source double-gate PNPN tunnel field effect transistor

Electrical noise in Ge-source double-gate PNPN tunnel field effect transistor

A Comprehensive Review on the Single Gate, Double Gate, Tri-Gate, and Heterojunction Tunnel FET for Future Generation Devices

A Comprehensive Review on the Single Gate, Double Gate, Tri-Gate, and Heterojunction Tunnel FET for Future Generation Devices

Impact of Drain Thickness Asymmetry on DC and Analog/RF Performance of an n-type SiGe/Si Double Gate TFET

Impact of Drain Thickness Asymmetry on DC and Analog/RF Performance of an n-type SiGe/Si Double Gate TFET

Impact of sidewall spacer materials and gate underlap length on negative capacitance double-gate tunnel field-effect transistor (NCDG-TFET)

In this study, a negative capacitance double-gate tunnel field-effect transistor (NCDG-TFET) with sidewall spacer engineering is proposed and its electrical characteristics are examined by technology computer-aided design (TCAD) simulation for lower subthreshold swing (SS) and higher on–off current ratio (Ion/Ioff) than conventional planar TFET. In detail, the dielectric constant (κ) and length of sidewall spacer (Lspc) which determine gate-to-source/drain underlap are optimized for an enhanced device performance. The simulation study shows that the sidewall spacers at source and drain underlap need to be designed differently for high Ion and low ambipolar current (Iamb). In case of source underlap, the HfO2 3 nm-Lspc can enhance outer fringing field and Ion. On the other hand, the SiO2 15 nm-Lspc at drain underlap can alleviate Iamb due to low outer fringing field. As a result, the asymmetric structure shows ∼ 1.5 times larger Ion and ∼ 4 orders lower Iamb with smaller SS and turn-on voltage (Von) than the conventional NCDG-TFET without sidewall spacer.

Impact of gate overlap and underlap on analog/RF and linearity performance of dual-material gate-oxide-stack double-gate TFET

Impact of gate overlap and underlap on analog/RF and linearity performance of dual-material gate-oxide-stack double-gate TFET

Analysis and evaluation of Si(1-x) Ge(x) pocket on sensitivity of a dual-material double-gate dopingless tunnel FET label-free biosensor

This work reports a sensitivity analysis for a dual-material double-gate dopingless Tunnel FET (DM-DG-DLTFET) biosensor carrying a Si(1-x) Ge(x) pocket for improved performance of an overall device. The biomolecules are immobilized in a cavity suitable for small-sized biomolecules detection and the performance of the device is investigated by calculating the electrical properties altered due to the dielectric modulation caused by presence and absence of biomolecules by commercially available ATLASTM tool. The Si(1-x) Ge(x) pocket placed under the cavity at source-channel interface helps to attain better on-current which is usually less in case of other reported structures of Tunnel FETs. The variation in the composition of Ge is observed to obtain enhanced sensitivity. The device is studied for threshold voltage sensitivity of neutral as well as charged biomolecules and the nature of the present biomolecule is also determined using the transconductance-to-current ratio (gm/Ids) which can also be considered as a sensing metric. The optimized device design has been proposed keeping track of the electrical and physical trade-offs. Our results show a maximum of 539.5 mV shift in the threshold voltage when dielectric constant (K) of the neutral biomolecule is varied from 1 to 12 which makes our device evidently an efficient candidate for label-free biosensing application.

Design, Simulation, and Work Function Trade for DC and Analog/RF Performance Enhancement in Dual Material Hetero Dielectric Double Gate Tunnel FET

Design, Simulation, and Work Function Trade for DC and Analog/RF Performance Enhancement in Dual Material Hetero Dielectric Double Gate Tunnel FET