Junctionless Tunnel Field Effect Transistor Research Articles

The Effect of a Dual Oxide - Dual Gate Material and a Sensitivity Analysis on the Performance of a Junctionless Tunnel FET

The Effect of a Dual Oxide - Dual Gate Material and a Sensitivity Analysis on the Performance of a Junctionless Tunnel FET

TCAD simulation study of heavy ion radiation effects on hetero junctionless tunnel field effect transistor

Semiconductor devices used in radiation environment are more prone to degradation in device performance. Junctionless Tunnel Field Effect Transistor (JLTFET) is one of the most potential candidates which overcomes the short channel effects and fabrication difficulties. In this work, 20 nm JLTFET is proposed with Silicon in the drain/channel region whereas source uses different materials, Silicon Germanium (SiGe), Gallium Nitride (GaN), Gallium Arsenide (GaAs), Indium Arsenide (InAs). The device performance is examined by subjecting it to heavy ion radiation at a lower and higher dose of linear energy transfer (LET) values. It can be seen that the most sensitive location is the source/channel (S/C) interface for SiGe, GaN and GaAs whereas the drain/channel (D/C) interface for InAs. Further analysis is carried out at these vulnerable regions by matching ION of all materials. The parameters, transient peak current (Ipeak), collected charge (QC), threshold voltage shift (ΔVth) and bipolar gain (β) are extracted using transient simulations. It is observed that for a lower dose of LET, Ipeak of SiGe is 27% lesser than InAs and for higher dose of LET, SiGe shows 56% lesser Ipeak than InAs. SiGe is less sensitive at lower and higher dose of LET due to reduced ΔVth, tunneling and electron density.

Assessment of Hetero-Structure Junction-Less Tunnel FET’s Efficacy for Biosensing Applications

Assessment of Hetero-Structure Junction-Less Tunnel FET’s Efficacy for Biosensing Applications

Single-Particle Irradiation Effect and Anti-Irradiation Optimization of a JLTFET with Lightly Doped Source.

In this article, the particle irradiation effect of a lightly doped Gaussian source heterostructure junctionless tunnel field-effect transistor (DMG-GDS-HJLTFET) is discussed. In the irradiation phenomenon, heavy ion produces a series of electron-hole pairs along the incident track, and then the generated transient current can overturn the logical state of the device when the number of electron-hole pairs is large enough. In the single-particle effect of DMG-GDS-HJLTFET, the carried energy is usually represented by linear energy transfer value (LET). In simulation, the effects of incident ion energy, incident angle, incident completion time, incident position and drain bias voltage on the single-particle effect of DMG-GDS-HJLTFET are investigated. On this basis, we optimize the auxiliary gate dielectric, tunneling gate length for reliability. Simulation results show HfO2 with a large dielectric constant should be selected as the auxiliary gate dielectric in the anti-irradiation design. Larger tunneling gate leads to larger peak transient drain current and smaller tunneling gate means larger pulse width; from the point of anti-irradiation, the tunneling gate length should be selected at about 10 nm.

Investigation of heavy ion radiation and temperature on junctionless tunnel field effect transistor

Investigation of heavy ion radiation and temperature on junctionless tunnel field effect transistor

Analysis of III-V material-based dual source T-channel junction-less TFET with metal implant for improved DC and RF performance

In this paper, two III-V material-based junctionless tunnel FET devices, D-1 and D-2, are proposed. The proposed device D-1 has a low bandgap (GaSb-based) dual source and a higher bandgap (GaAs-based) T-channel junctionless, and the proposed device D-2 has the same architecture as D-1 in addition to a metal strip implant in the gate oxide near both source regions. Due to junctionless architecture, the proposed D-1 and D-2 eliminate random dopant fluctuations (RDF), remove the need for high thermal budgeting, and give better performance with less variability. The wide bandgap (GaAs) T-channel and the drain region formed far from the gate fully suppress the ambipolarity for both the proposed D-1 and D-2. The low-bandgap GaSb material in the source improves the ON current for D-1 and D-2. Compared to the conventional junctionless TFET (JL-TFET), the proposed D-2 (even at a lower bias of 0.5 V) improves the ON current by 1.7 times and the ION/IOFF ratio by 216.66 times, with a much-reduced average subthreshold swing value of 32.7 mV/dec compared to 70 mV/dec of the conventional JL-TFET. Furthermore, the proposed D-2 also provides much improved RF performance with a higher transconductance (gm) of 147.8 μs, higher cut-off frequency (fT) of 32.26 GHz, a higher gain-bandwidth product (GBW) of 3.52 GHz, higher transconductance-frequency product (TFP) of 286 GHz, and a lower transit time (τ) of 5 × 10–12 s. Furthermore, we analyze various linearity parameters such as gm2, gm3, VIP2, VIP3, IIP3, and IMD3 for both D-1 and D-2, and our findings indicate that D-2 exhibits improved linearity performance.

Modeling and Simulation of a TFET-Based Label-Free Biosensor with Enhanced Sensitivity

This study discusses the use of a triple material gate (TMG) junctionless tunnel field-effect transistor (JLTFET) as a biosensor to identify different protein molecules. Among the plethora of existing types of biosensors, FET/TFET-based devices are fully compatible with conventional integrated circuits. JLTFETs are preferred over TFETs and JLFETs because of their ease of fabrication and superior biosensing performance. Biomolecules are trapped by cavities etched across the gates. An analytical mathematical model of a TMG asymmetrical hetero-dielectric JLTFET biosensor is derived here for the first time. The TCAD simulator is used to examine the performance of a dielectrically modulated label-free biosensor. The voltage and current sensitivity of the device and the effects of the cavity size, bioanalyte electric charge, fill factor, and location on the performance of the biosensor are also investigated. The relative current sensitivity of the biosensor is found to be about 1013. Besides showing an enhanced sensitivity compared with other FET- and TFET-based biosensors, the device proves itself convenient for low-power applications, thus opening up numerous directions for future research and applications.

Design and Investigation of a Single Gate Heterostructure Junctionless Tunnel FET for the Gas Detection

In this paper, a single gate junctionless heterostructure TFET gas sensor (SiGe-SG-JLTFET) is presented, and its effectiveness is examined. The high-k gate dielectric (HfO2) and low bandgap alloy prove to be a great combination to boost the drain current. The leakage current is controlled by the presence of a silicon body in the channel and drain. We have considered a Palladium metal with a suitable work-function in the gate catalyst for better sensitivity purposes. The sensor modulates the flat band voltage and Capacitance-Voltage characteristics with the adsorption of gas atoms at the Palladium/HfO2 and Palladium surfaces. Consequently, the ON-state current is affected, which is treated as a sensing measure. The gas sensor’s electrostatic analysis is investigated in terms of I-V characteristics, current components, band energy for both ON- and leakage conditions, maximum electric field, BTBT rate, and carrier concentrations. Similarly, the sensitivity analysis consists of drain current sensitivity (SID), current ratio sensitivity (Sratio), and average SS sensitivity (SSS). The investigation has been carried out with the change in gas pressure in terms of work-function, temperature (0K), and interface trap charges (ITC) using a TCAD device simulator. The proposed gas sensor exhibits a (SID)max of 2.41 × 106 and Sratio of 3.89 × 104 with higher pressure concentration at room temperature respectively.

Performance Assessment of a Junctionless Heterostructure Tunnel FET Biosensor Using Dual Material Gate

Biosensors based on tunnel FET for label-free detection in which a nanogap is introduced under gate electrode to electrically sense the characteristics of biomolecules, have been studied widely in recent years. In this paper, a new type of heterostructure junctionless tunnel FET biosensor with an embedded nanogap is proposed, in which the control gate consists of two parts, namely the tunnel gate and auxiliary gate, with different work functions; and the detection sensitivity of different biomolecules can be controlled and adjusted by the two gates. Further, a polar gate is introduced above the source region, and a P+ source is formed by the charge plasma concept by selecting appropriate work functions for the polar gate. The variation of sensitivity with different control gate and polar gate work functions is explored. Neutral and charged biomolecules are considered to simulate device-level gate effects, and the influence of different dielectric constants on sensitivity is also researched. The simulation results show that the switch ratio of the proposed biosensor can reach 109, the maximum current sensitivity is 6.91 × 102, and the maximum sensitivity of the average subthreshold swing (SS) is 0.62.

Design and Parametric Analysis of Charge Plasma Junctionless TFET for Biosensor Applications

This paper presents a new design of charge plasma junctionless tunnel field effect transistor (CP JLTFET) with improved ON current, surface potentials. For the ease of fabrication, source and drain regions are induced in intrinsic silicon material using proper metal workfunctions. The rate of tunneling of electrons is found more in case of proposed CP JLTFET. The cavity length is varied between 8 nm and 10 nm and different dielectric constants have been used. This increased the ON state performance of device i.e ON drive current, potential and electric field. The increase in tunneling of electrons is mainly due to high recombination of carriers in the channel region. The proposed device simulated their electrical parameters like drain current, surface potentials, electric field, and energy bands with different dielectric constants. These excellent performance parameters of the proposed device with an appropriate material can be used for sensing application of biomolecules by introducing a cavity in the device.

Guest Editorial: Materials & Devices for Advanced Flexible Sensors

The papers in this special section focus on materials and devices for flexible sensors. Presents recent advances in skin electronics, touch sensors for flexible display, near-infrared spectroscopy (NIRS) and organic electrochemical transistors (OECT), respectively. Three research article introduces new methods in flexible pressure sensing array, ammonia sensors and charge plasma junctionless tunnel field effect transistor (CP JLTFET), respectively.

Junctionless tunnel field-effect transistor with a modified auxiliary gate, a novel candidate for high-frequency applications

In this paper, we propose a novel junctionless tunnel field-effect transistor that uses a tunneling gate and a modified auxiliary gate. The first one is employed to enhance the DC/AC performance of the device, and the second one is used to suppress the ambipolar conduction. Due to a uniformly doped Silicon body, dopant diffusion and the formation of abrupt P–N junctions are no longer a big concern. We also illustrate that the fabrication process of heterogate junctionless tunneling field-effect transistor (HJL-TFET) is fully compatible with CMOS technology. Using a calibrated device simulator, the impact of non-idealities such as traps and temperature is thoroughly investigated. The quantum confinement, effect which severely degrades low channel thickness TFETs is also assessed. Furthermore, the impact of ferroelectric material on the transfer characteristics of our device has been studied. Based on the results, HJL-TFET shows desirable parameters such as the ION = 345 μA/μm, SSAVG = 39.34 mV/dec, ION/IOFF = 5.67 × 108, and fT = 225.5 GHz.

DC/RF performance and temperature sensitivity of ground-plane based JLTFET

ABSTRACT This paper analyses the effect of temperature variations on the device performance of a ground plane junctionless tunnel field effect transistor (GP-JLTFET) with a high-K gate stack. Ground plane screens the electric field at the drain interface, which results in a higher effective channel length. This leads to highly suppressed ambipolarity and enhancement of the drive current. The junctionless device structure reduces the complexity of high-temperature doping processes as well. As high- gate oxide and metal gate are incorporated, this also aids in increasing the gate controllability and reduced leakage. As the tunnelling mechanism is temperature-dependent, hence, for investigating the feasibility of device application at elevated temperature, these temperature variation effects need to be analysed in depth. The primary goal of this investigation is to analyse the device dc performance parameters like drain current characteristics and subthreshold slope (SS), threshold voltage (), and ratio. Furthermore, the impact of temperature on analogue/RF figures of merit has also been analysed in detail here.

Impact of High-temperature and Interface Traps on Performance of a Junctionless Tunnel FET

Impact of High-temperature and Interface Traps on Performance of a Junctionless Tunnel FET

Sensitivity Assessment of Electrically Doped Cavity on Source Junctionless Tunnel Field-Effect Transistor-Based Biosensor

The tunnel field-effect transistor (TFET) has emerged as a promising device for biosensing applications due to band-to-band tunneling (BTBT) operation mechanism and a steep subthreshold swing. In this paper, an electrically doped cavity on source junctionless tunnel field-effect transistor (ED-CS-JLTFET)-based biosensor is proposed for label-free detection of biomolecules. In the proposed model, the electrically doped concept is enabled to reduce fabrication complexity and cost. In order to create a nano-cavity at the source region, some portion of the dielectric oxide of the polarity gate terminal is etched away. To perceive the presence of biomolecules, two important properties of biomolecules, such as dielectric constant and charge density, are incorporated throughout the simulation. The sensing performance of the proposed ED-CS-JLTFET-based biosensor has been analyzed in terms of transfer characteristics, threshold voltage and subthreshold swing. In addition, the sensitivity of the proposed biosensor has also been analyzed with respect to different fill factors (FFs), varying nano-cavity dimension and work-function of the control gate. It is found from the simulated results that the proposed ED-CS-JLTFET-based biosensor offers higher current sensitivities with neutral, positively charged and negatively charged biomolecules of [Formula: see text] (at k [Formula: see text]), [Formula: see text] (at [Formula: see text] and [Formula: see text] C[Formula: see text]cm[Formula: see text]) and [Formula: see text] (at k [Formula: see text] and [Formula: see text] C[Formula: see text]cm[Formula: see text]), respectively.

Impact of tunnel gate process variations on analog/radio frequency (microwave) and small signal parameters of hetero‐material tunneling interfaced charge plasma junctionless tunnel field effect transistor

AbstractThis paper proposes a dual metal gate, hetero‐material tunneling interfaced junctionless tunnel field effect transistor (TFET), (DMG‐HJLTFET), utilizing III–V compound semiconducting materials, InAs (low band‐gap source material)/GaAs (higher band‐gap channel and drain material) by applying the band‐gap and dual material gate engineering. The 2‐D TCAD simulations have been executed to explore the impact of tunnel gate process variations—work function and length on DC and analog figure of merits (FOMs) of DMG‐HJLTFET. The extracted result parameters have also been compared to SMG (single metal gate)‐HJLTFET and conventional Si‐JLTFET. The DMG‐HJLTFET attains improved ON current in the range of 88.5 × 10−6 A/μm and OFF current remains as low as 2.89 × 10−16 A/μm. It exhibits a high current switching ratio of 3.1 × 1011 as compared to SMG‐HJLTFET (ION = 24 × 10−6 A/μm and ION/IOFF = 1.4 × 1011) and Si‐JLTFET (ION = 7 × 10−6 A/μm and ION/IOFF = 1.8 × 106). Further, the radio frequency/microwave (RF) parameters such as power gains (h12, UPG, and Gma), fmax, and GBP have been compared for all three aforementioned devices. Moreover, the small signal admittance (Y) parameters have been examined to explore the possible scope of DMG‐HJLTFET for future internet of everything communications and fast switching applications.

Influence of source electrode metal work function on polar gate prompted source hole plasma in arsenide/antimonide tunneling interfaced junctionless TFET

Numerous studies have explored the impact of control gate and polar gate (PG) on the retention of hole and electron charge plasma to induce the source and channel region polarity in junctionless tunnel field effect transistor (JLTFET). However, PG is not the only one responsible for the retention of hole plasma in the p+ prompted source but the hole plasma near the interface of source electrode metal (SEM) and p+ prompted source (SEM/S) is influenced by the choice of SEM work function too. This paper features a comprehensive investigation of the mutual significance of PG and SEM work function on p+ prompted source to study key analog characteristics of arsenide/antimonide tunneling interfaced hetero-material JLTFET (HJLTFET), which is unexplored in the literature otherwise. We have considered three metals—W (4.55 eV), Mo (4.65 eV), and Pd (5.3 eV) as the source electrodes in HJLTFET. For SEM work function lesser than p+ prompted source (W and Mo), the Schottky contact is formed by the depletion of hole plasma near SEM and p+ prompted source interface. This results in the immediate current inhibition at source to channel interface caused by an undesired movement of electrons en route to the Schottky interface. The Schottky tunneling phenomenon is considered by implementing the universal Schottky tunneling (UST) model to study the underestimated drain current of HJLTFET. However, the UST model becomes inconsequential for SEM work function higher than p+ prompted source (Pd) as hole plasma is preserved by the ohmic contact formation.

Reliability and sensitivity analysis of double inverted-T nano-cavity label-free Si:HfO2 ferroelectric junctionless TFET biosensors.

In this work, we propose and simulate an ultrasensitive, label-free, and charge/dielectric modulated Si:HfO2 ferroelectric junctionless tunnel field effect transistor (FE-JL-TFET) based biosensor. The proposed sensing device employs a dual inverted-T cavity and uses ferroelectric gate stacking of Si-doped HfO2, a key enabler of negative capacitance (NC) behavior. The two cavities are carved in gate-source underlap regions by a sacrificial etching technique to sense biomolecules such as streptavidin (2.1), bacteriophage T7 (6.3) and gelatin (12). Two dimensional (2D) calibrated simulations have been performed and the impact of various device parameters, including cavity length and height, on various performance measuring parameters has been studied. It has been observed that the biosensor exhibits better sensitivities for both neutral and charged biomolecules. The maximum values of the ION/IOFF sensitivity for the neutral, positively charged and negatively charged biomolecules are as high as 3.77 × 109, 5.85 × 109, and 1.72 × 1010, respectively. It has been observed that optimizing the cavity length and height can significantly improve the sensing capability of the proposed device. The comparative analysis of the proposed biosensor and other state of the art biosensors shows a significant improvement in the sensitivity (101 to 106 times) in the proposed biosensor. The detrimental effect of interface trapped charges on the biosensor performance is also analyzed in detail.

Enhanced Performance Double-gate Junction-less Tunnel Field Effect Transistor for Bio-Sensing Application

In this work, a double gate junction-less tunnel FET (DG-JLTFET) has been evaluated for biosensing applications. Tunnelling is the concept in JLTFET which is a heavily doped JL transistor, by decreasing the barrier length between the source and channel of the device which is easily used for switching (ON and OFF) purpose. Based on the research and simulation so far on JLTFET, this has achieved a greater performance when compared to that of MOSFET. JLTFET with more dielectric (k) and low K spacers will give an ON current (0.1 mA/µm) for gate voltage 3V and for off current of (10−15 A/ µm) and performance with Ion/Ioff ratio at 1012 and subthreshold swing with 60 mV/dec is obtained at 20 nm length of the gate at room temperature. So, JLTFET is a better device for switching performance. The evaluation of device performance is also done based on different cavity thicknesses and different dielectric constants. Including these parameters, double gate-pocket-junction-less TFET is highly used in biosensor applications. In the following, we demonstrate high performance based on pocket region which is introduced to implement in JLTFET for biosensor label-free detection

Negative Capacitance Dual Electrode Junctionless TFET Based on Si Doped HfO 2 Ferroelectric Layer: Proposal and Optimization

This work reports negative capacitance dual electrode junctionless tunnel field effect transistor (NC-DE-JLTFET) based on Si doped HfO 2 ferroelectric (FE) layer as gate-stack. This FE layer is sandwiched between conventional gate dielectric layer and gate metal electrode. As the domains of FE get aligned due to polarization in the applied electric field directions it realizes intrinsic voltage amplification. This facilitates the smaller voltage swing in the gate voltage resulting in a larger swing in drive current. This enhances gate controlability, improves scalability, lowers threshold voltage and steepers sub-threshold slope (SS). However the most crucial designing aspect of negative capacitance (NC) based device is stabilizing the net capacitance of the structure otherwise it can cause system instability due to the NC behavior. In order to stabilize this NC effect here optimization of FE layer thickness has been carried out by parametric sweep optimization. The study reported minimum SS as 20 mV/dec with FE thickness of 2.5 nm. As JLTFET is a dopingless structure, source and drain side dielectric oxide thicknesses dictate the source and drain side induced doping, respectively. Hence the device performance estimation in terms of these thickness variations is also presented here in detail.