Conventional Field Effect Research Articles

Analysis Of Output Characteristics of Three Different Ga2O3 Heterojunction UV Photodetectors

Phototransistors can be used as switches and amplifiers in digital and ultraviolet photodetectors, respectively. Gallium oxide ( Ga2O3) is a common material used to make devices like transistors. However, these photodetectors usually face some problems of drain current saturation and bias saturation. But regulating the transistor switching ratio usually requires adding a voltage to the gate terminal, and will cause high current flow throughout the transistor if the gate power supply pressurized beyond the threshold. The structure of a LET is similar to that of a conventional field effect transistor (FET), and they also have similar current and voltage output characteristics, but the difference is that the LET is also subject to light regulation. This paper mainly concentrates on the analysis of LFT devices made of heterojunction of three different materials n- /p-GaN, Nanoporous /GaN and Graphene/β- , and analyzes and compares a series of key parameters such as switch ratio and responsiveness, etc. Through these comparisons, this paper can more clearly understand what LFT devices made of different materials can better adapt to the needs of different experiments. Under different voltage ranges and light intensity, LFT devices made of different materials can better adapt to the needs of experiments.

Evaluating the performance of triple and double metal gate charge plasma transistors for applications in biological sensors at a dual cavity location

BackgroundBiosensors have become essential tools in biotechnology, environmental monitoring, and healthcare industries due to their ability to detect and analyze biological signals. However, conventional Tunnel Field-Effect Transistors (TFETs) used in biosensors face challenges like reduced ON-state current, random dopant fluctuations, and complex manufacturing processes, which limit their effectiveness. AimThe study aims to investigate the effectiveness of Charge Plasma-based Tunnel Field-Effect Transistors (CP-TFETs) with dual and triple metal gate-dual cavity locations for improving the sensitivity and performance of biosensors. MethodologyThe study compares dual and triple metal gate CP-TFET configurations for signal amplification and detection in biosensors. The CP-TFETs use high-k gate dielectric materials to enhance ON-state current and reduce OFF-state current, while the impact of neutralized and charged substances in the cavities on surface energy, electric field, and energy bands is analyzed. ResultsThe triple metal gate configuration demonstrated superior sensitivity in detecting biomolecules compared to the dual metal gate. By utilizing high-k materials and optimizing the gate work function, the triple metal gate approach achieved higher drain current and reduced OFF-state current, leading to improved overall performance. ConclusionThe triple metal gate CP-TFET outperforms its dual metal counterpart in biosensor applications, offering higher sensitivity, increased ON-state current, and improved detection capabilities, making it a promising approach for enhancing biosensor effectiveness.

Negative Capacitance Field Effect Transistors based on Van der Waals 2D Materials.

Steep subthreshold swing (SS) is a decisive index for low energy consumption devices. However, the SS of conventional field effect transistors (FETs) has suffered from Boltzmann Tyranny, which limits the scaling of SS to sub-60mVdec-1 at room temperature. Ferroelectric gate stack with negative capacitance (NC) is proved to reduce the SS effectively by the amplification of the gate voltage. With the application of 2D ferroelectric materials, the NC FETs can be further improved in performance and downscaled to a smaller dimension as well. This review introduces some related concepts for in-depth understanding of NC FETs, including the NC, internal gate voltage, SS, negative drain-induced barrier lowering, negative differential resistance, single-domain state,and multi-domain state. Meanwhile, this work summarizes the recent advances of the 2D NC FETs. Moreover, the electrical characteristics of some high-performance NC FETs are expressed as well. The factors which affect the performance of the 2D NC FETs are also presented in this paper. Finally, this work gives a brief summary and outlook for the 2D NC FETs.

A nonvolatile bidirectional reconfigurable FET based on S/D self programmable floating gates.

A nanoscale nonvolatile bidirectional reconfigurable field effect transistor (NBRFET) based on source /drain (S/D) self programmable floating gates is proposed. Comparing to the conventional reconfigurable field effect transistor (RFET) which requires two independently powered gates, the proposed NBRFET requires only one control gate. Beside, S/D floating gates are introduced. Reconfigurable function is realized by programming different types of charges into the S/D floating gates through biasing the gate at a positive or negative high voltage. The effective voltages of the S/D floating gates are determined jointly by the quantity of the charge stored in the S/D floating gates and the gate voltage. In addition, the charge stored in the floating gate has an effect of reducing the energy band bending near the source/drain regions when the gate is reversely biased, thereafter, the band to band tunneling (BTBT) leakage current can be largely decreased. The scale of the proposed NBRFET can be reduced to nanometer level. The device performances such as the transfer and output characteristics are verified by device simulation, which proves that the proposed NBRFET has very good performance in the nanometer scale.

Giant tunneling magnetoresistance in in-plane double-barrier magnetic tunnel junctions based on MXene Cr2C.

The discovery of two-dimensional (2D) magnetic materials makes it possible to realize in-plane magnetic tunnel junctions. In this study, the transport characteristics of an in-plane double barrier magnetic tunnel junction (IDB-MTJ) based on Cr2C have been studied by density functional theory combined with the nonequilibrium Green's function method. The results showed its maximum tunneling magnetoresistance ratio (TMR) value reached 6.58 × 1010. Its minimum TMR value (3.86 × 106) was also comparable to those of conventional field effect transistors (FETs). Due to its giant TMR and unique structural characteristics, the IDB-MTJ based on Cr2C has great potential applications in magnetic random access memory (MRAM) and logic computing.

(Digital Presentation) Power Efficient Transistors with Low Subthreshold Swing Using Abrupt Switching Devices

With the rapid development of transparent integrated circuits, transistors with extremely low subthreshold swing (SS) is becoming a necessary requirement. Here, we fabricated three transparent device structures that show abrupt electrical switching and make their series connection to the source terminal of the conventional field effect transistors (FET) to lower the SS value. Firstly, we demonstrate an environment friendly, disposable, and transparent conductive bridge random access memory (CBRAM) device composed of a cellulose nanocrystals active layer. Our CBRAM consists of a silver (Ag) electrochemically active top electrode and a cellulose nanocrystals-based switching layer on the FTO coated glass substrate. Devices with CBRAM can enable FET with an ultra-steep slope that is SS < 0.24 mV/dec and has a significantly high on/off ratio (~105) by switching the Ag metallic filament between on and off. Niobium oxide (NbO2) based threshold switching devices and zinc oxide (ZnO) based flexible Schottky diodes that show electrical breakdown were also stacked with FET, which gave SS values < 0.74 mV/dec and < 5.20 mV/dec, respectively. Comparatively, a nano-watt transistor called filament transistor (FET + CBRAM stack) can significantly improve the SS slope value with the lowest leakage current (~nA) and a record low turn on-voltage (~0.2 V) with a set power of only ~197 nW compared to the other series stack, which thereby attracts the attention of low power operations. Keywords: filament transistor, threshold switching, Schottky diode, subthreshold swing, on/off ratio Figure 1

Cationic effects on solid polymer electrolyte-gated organic transistors

Unlike the conventional organic field effect transistors using traditional gate dielectric layer, the electrolyte-gated organic transistors (EGOTs) use electrolytes as gate media, resulting in a tunable highly conductive channel. Due to their unique advantages, such as: higher gate-capacitance and lower operating voltages, the EGOTs are subject to extensive research. In a solid polymer electrolyte gate, the solvated cations and anions are initially evenly distributed in the ion-conducting polymer, under gate bias, the counter ions then drift towards the electrolyte/active layer interface and under high enough bias they might insert into the active layer and dope the polymer. Given the above mechanism, the anions and cations play the crucial role for gate operation in EGOTs. Although how the anions significantly affect the organic electrochemical transistors using the liquid electrolyte media was investigated, the ionic effect in the solid electrolyte-gated transistors has been barely reported. In this work, the effects of cation on the device performance of solid polymer electrolyte-gated organic transistors have been systematically studied. In the devices made with alkali perchlorates, a systematic shift in threshold voltage, current hysteresis, and response time with increasing cation size/mass has been observed. A lower threshold voltage is obtained with the smaller cation which also displays smaller hysteresis and faster response due to faster migration of smaller cations in polymer electrolyte. This study suggests the smaller cations should be used in the fabrication of solid polymer EGOTs. • Cationic effects on the solid electrolyte (PEO:alkali perchlorate salt)-gated organic transistors (EGOTs) are studied. • The smaller cation based device displays lower threshold voltage, smaller hysteresis, and faster response. • The cation motion in polymer electrolyte is key for performances of EGOTs.

Power efficient transistors with low subthreshold swing using abrupt switching devices

With the rapid development of transparent integrated circuits, transistors with extremely low subthreshold swing (SS) is becoming a necessary requirement. Here, we fabricated three transparent device structures that show abrupt electrical switching and make their series connection to the source terminal of the conventional field effect transistors (FET) to lower the SS value. Firstly, we demonstrate an environment friendly, disposable, and transparent conductive bridge random access memory (CBRAM) device composed of a cellulose nanocrystals active layer. Our CBRAM consists of a silver (Ag) electrochemically active top electrode and a cellulose nanocrystals-based switching layer on the FTO coated glass substrate. Devices with CBRAM can enable FET with an ultra-steep slope that is SS < 0.24 mV/dec and has a significantly high on/off ratio (~105) by switching the Ag metallic filament between on and off. Niobium oxide (NbO2) based threshold switching devices and zinc oxide (ZnO) based flexible Schottky diodes that show electrical breakdown were also stacked with FET, which gave SS values < 0.74 mV/dec and < 5.20 mV/dec, respectively. Comparatively, a nano-watt transistor called filament transistor (FET + CBRAM stack) can significantly improve the SS slope value with the lowest leakage current (~nA) and a record low turn on-voltage (~0.2 V) with a set power of only ~197 nW compared to the other series stack, which thereby attracts the attention of low power operations.

Flexible Diodes with Low Breakdown Voltage for Steep Slope Transistors and One Diode‐One Resistor Applications

AbstractTransparent and flexible diodes could be useful for future transparent electronics. Here such diodes are discussed with electrical breakdown (EBR) comprises of W/ZnO/ITO structure on the polyethylene terephthalate substrates. The three‐layered structure shows rectifying characteristics with low breakdown voltage originated from the Schottky barrier at the W/ZnO (0.8 eV) and the ZnO/ITO (0.1 eV) interfaces. Mechanical endurance is retained after different bending strengths and the rectification ratio is showed stability for 104 cycles without any significant degradation. Steep slope transistors are designed by implementing such diodes in series with the conventional field effect transistors. Such diode plus transistor stack enables field effect transistors with steep subthreshold swing of &lt; 5.2 mV dec−1 and an internal current amplification due to negative differential resistance induces across the Schottky diodes during the EBR. Also, one diode‐one resistor structure is successfully demonstrated by connecting the flexible diodes and resistive memory in series for applications in high density integrated non‐volatile memory applications.

Temperature dependence of analogue/RF performance, linearity and harmonic distortion for dual‐material gate‐oxide‐stack double‐gate TFET

This article presents an investigation report of the effects of temperature variation in the range of 300 to 480 K on electrical performance parameters of conventional dual-material double-gate tunnel field effect transistor (DMDG-TFET) and dual-material gate-oxide-stack double-gate tunnel field effect transistor (DMGOSDG-TFET). This report shows an analysis and comparison of the impacts of operating temperature variation on both the devices in terms of DC, analogue/RF, linearity and harmonic distortion parameters with the help of simulation results obtained using a numerical device simulator. It could be stated that DMGOSDG-TFET is more insensitive with respect to temperature variation in terms of DC, analogue/RF and linearity performances as compared to conventional DMDG-TFET. Moreover, in terms of harmonic distortion characteristics DMGOSDG-TFET is found to be more stable with temperature variation as compared to DMDG-TFET.

Using Anisotropic Insulators to Engineer the Electrostatics of Conventional and Tunnel Field-Effect Transistors

Materials scientists have developed a wide variety of anisotropic insulators that could offer avenues to separately manipulate lateral and perpendicular electric fields if implemented as the gate insulators or spacers in field-effect transistors (FETs). However, there have been no works that have studied how the electrostatics of an FET can be engineered by using anisotropic insulators. We address this gap in knowledge by simulating metal–oxide–semiconductor FETs (MOSFETs) and tunnel FETs (TFETs) while separately varying the in-plane and out-of-plane permittivities of their insulators. Our results show that MOSFETs should have gate insulators and spacers with small in-plane and large out-of-plane permittivities to maximize their performance, and we demonstrate that an FET with a single anisotropic insulator that covers both the gate dielectric and spacers can outperform a similar structure that uses hafnium dioxide for the gate dielectric and air for the spacers. We also demonstrate that anisotropic gate insulators can greatly improve the subthreshold swing and ON-currents of TFETs, and we introduce a new type of heterogate dielectric for TFETs by manipulating the gate insulator’s in-plane permittivity. We anticipate that the results of this study will motivate experimental research toward developing FETs with anisotropic insulators.

Performance analysis of graphene based operational amplifier with conventional amplifier for future communications

Graphene plays a vital role in today’s communication because of its excellent and novel properties. Here, in this paper, we present a comparative analysis of graphene based field effect transistor (FET) as operational amplifier with a conventional Metal-Oxide-Semiconductor (MOSFET) for analog applications. A graphene nanoribbons (GNR) of armchair type is used in the model of operational amplifier (op-amp). The electronic properties as a channel are deeply investigated by calculating the band structure, density of states and cohesive energy. GNRs have great potential in low power devices and for future applications, low power dissipation is essential for any device. Therefore, this paper aims to compare two op-amps. One is based on a GNR channel simulated in Virtual Nanolab (VNL) and other is based on a conventional field effect transistor (FET) channel. Using the op-amp model simulating in H-SPICE, we are able to calculate the voltage gain, output resistance and power dissipation of GNR based op-amp and compare it with conventional MOSFET. Our study shows that graphene based circuits will exploit more applications due to lower power dissipation and low output resistance.

Mixed ion-electron transport in organic electrochemical transistors

Organic electrochemical transistors (OECTs) have shown great promise in a variety of applications ranging from digital logic circuits to biosensors and artificial synapses for neuromorphic computing. The working mechanism of OECTs relies on the mixed transport of ionic and electronic charge carriers, extending throughout the bulk of the organic channel. This attribute renders OECTs fundamentally different from conventional field effect transistors and endows them with unique features, including large gate-to-channel capacitance, low operating voltage, and high transconductance. Owing to the complexity of the mixed ion-electron coupling and transport processes, the OECT device physics is sophisticated and yet to be fully unraveled. Here, we give an account of the one- and two-dimensional drift-diffusion models that have been developed to describe the mixed transport of ions and electrons by finite-element methods and identify key device parameters to be tuned for the next developments in the field.

Core Insulator Nanosheet Transistor and Structure Optimization to Improve Gate Electrostatic Characteristics.

This paper proposes the core insulator nano-sheet transistor structure for improved electrostatic characteristics by adding an oxidation process to the conventional Nano-sheet field effect transistor process. The additional insulated core improves the drain induced barrier lowering and the subthreshold slope properties by enhancing the gate controllability. The major advantage of the proposed structure is that it can be fabricated using the conventional nano-sheet field effect transistor process by simply adding another oxidation step. We compared the performance of our proposed device to that of FinFET and nano-sheet field effect transistor at sub 3 nm node using technology computer-aided design simulation. An optimal device structure including the oxide thickness and channel stacking is suggested with consideration for drive current, leakage and electrostatic characteristics.

Impact of Hetero-Dielectric Ferroelectric Gate Stack on Analog/RF Performance of Tunnel FET

We have investigated the characteristics of a hetero-dielectric ferroelectric tunnel (HD-FeTFET). Extensive simulations show that using a hetero-dielectric gate architecture in the lateral direction (non-ferroelectric/ferroelectric/non-ferroelectric) results in more desirable analog/RF characteristics. The proposed structure is compared with conventional tunnel field effect transistors (TFETs) and ferroelectric TFET (FeTFET). Simulation results manifest that HD-FeTFET is superior to other compared structures, and benefits from both ferroelectric and hetero-dielectric structure. Negative capacitance effect in ferroelectric causes a step-up voltage transformer, as a result the subthreshold swing decreases. Owing to two different dielectric constants in the hetero-dielectric structure, the electric field enhances; thereby, the on-state current increases. In this paper, important analog/RF figures of merit, such as cut-off frequency (fT), maximum oscillation frequency (fmax), transconductance frequency product, and intrinsic time delay (τ), are investigated. Also, linearity parameters including VIP2, VIP3, IIP3, and the 1-dB compression point are considered. We achieve average sub-threshold swing of 14 mV for 5 decades for HD-FeTFET, and is improved by ∼ 48% and ∼ 30% for TFET and FeTFET, respectively. Moreover, the ION/IOFF ratio and the on-state current for the proposed structure are 1011 and 5.3 × 10−7 (A/μm), respectively.

Analytical Modeling of Ion Sensitive Broken Gate TFET for pH Sensing Applications

In this letter, structural modification of a conventional tunnel field effect transistor (TFET) device is presented to act as an effective pH sensor. The change in hydrogen ion concentration in the aqueous solution is to be detected by the present broken gate (BG) TFET based pH sensor with its semiconducting material being modified as the electrolytic region. The chemical reactions at the interface of the gate dielectric and the electrolyte generate a surface charge density, making the device sensitive to pH. An analytical model of the BG TFET is developed here to capture the impact of pH variations on surface potential and drain current characteristics of the device. The sensitivity of the device is then investigated by extracting the threshold voltage shift as the pH values of the injected solution are varied. The accuracy of the analytical results is further corroborated by ATLAS simulator extracted data.

A Silicon Nanowire Ferroelectric Field‐Effect Transistor

AbstractThe design and characterization of a Schottky‐type ferroelectric field‐effect transistor based on a nominally undoped silicon nanowire are reported. The nanowire transistor is fabricated by top‐down technology starting from a silicon‐on insulator wafer. A thin ferroelectric Hf0.38Zr0.62O2 layer is integrated via a gate‐first approach. Abrupt Schottky source/drain contacts to the undoped silicon are provided by NiSi2 formation. Two distinct nonvolatile transistor states (programmed and erased) are observed in correspondence to negative and positive polarization in the ferroelectric layer, delivering a memory window of ≈1.5 V and, differently to conventional ferroelectric field effect transistors, yielding an on‐current difference of up to 30%. These results are interpreted as a combination of effects, arising from the proximity of the ferroelectric layer to both the channel and the Schottky‐junction regions. The threshold voltage shift, due to a polarization field acting on the channel, adds up to a polarization field‐driven tuning of the current injection through the Schottky‐source junction. This provides a strategy for manufacturing Schottky‐type nanoscale transistors with the add‐on nonvolatile option, following a complementary metal‐oxide‐semiconductor compatible process. In particular, the device concept is of great interest for achieving nonvolatile polarity modification in reconfigurable field‐effect transistors.

Microfluidic opportunities in printed electrolyte-gated transistor biosensors.

Printed electrolyte-gated transistors (EGTs) are an emerging biosensor platform that leverage the facile fabrication engendered by printed electronics with the low voltage operation enabled by ion gel dielectrics. The resulting label-free, nonoptical sensors have high gain and provide sensing operations that can be challenging for conventional chemical field effect transistor architectures. After providing an overview of EGT device fabrication and operation, we highlight opportunities for microfluidic enhancement of EGT sensor performance via multiplexing, sample preconcentration, and improved transport to the sensor surface.

MoS2 nanosheets based Electric Double Layer Transistor

With the advancement of the present research in the field of transistors, with the miniaturization of devices it has become a great challenge of achieving high carrier density and lower operational voltage in the conventional field effect transistors, where in the normal case we usually see low capacitance and dielectric breakdown of gate dielectrics. And hence, presently, the development of the electric double layer technology with high charge career accumulation at the channel/electrolyte interface has been successful to achieve this motto. And presently several other superior characteristics like- superconductivity, metal insulator transition and tunable thermoelectric behaviour have been observed both theoretically and experimentally.

Structural Modification of Doped Tunnel Field Effect Transistor for Enhanced Conduction Current and Lower Subthreshold Swing

The material solubility in the source region and abrupt source/channel junction profile are the major concern which is responsible for the improvement of the electrical characteristics of conventional physical doped tunnel field effect transistor (PD-TFET). For this, an additional negatively polarised electrode is mounted in P+ (source) – N (channel) – N+ (drain) structure over the source region to overcome material solubility. This improves the electrical characteristics of the device. Along with this, we have implanted a low workfunction metal layer (ML) in the oxide layer under the gate electrode for creating more abruptness at the junction to improve the subthreshold swing (SS) of the device. Thus, the proposed concept improves the DC/RF performance of the doped TFET device. Further to this, the optimization of metal layer workfunction and misalignment of metal layer in TFET have been performed to get optimum device characteristics. In addition to this, for the suppression of ambipolar behaviour, gate electrode is shorted from the drain side. Due to short length of gate electrode tunneling barrier width at the drain/channel junction increases, hence the tunneling probability decreases which reduces the ambipolar current to parasitic current. Shortening of gate electrode also improves the RF performance.