Showing papers on "Field-effect transistor published in 2022"

High-κ perovskite membranes as insulators for two-dimensional transistors

Abstract: The scaling of silicon metal-oxide-semiconductor field-effect transistors has followed Moore's law for decades, but the physical thinning of silicon at sub-ten-nanometre technology nodes introduces issues such as leakage currents1. Two-dimensional (2D) layered semiconductors, with an atomic thickness that allows superior gate-field penetration, are of interest as channel materials for future transistors2,3. However, the integration of high-dielectric-constant (κ) materials with 2D materials, while scaling their capacitance equivalent thickness (CET), has proved challenging. Here we explore transferrable ultrahigh-κ single-crystalline perovskite strontium-titanium-oxide membranes as a gate dielectric for 2D field-effect transistors. Our perovskite membranes exhibit a desirable sub-one-nanometre CET with a low leakage current (less than 10-2 amperes per square centimetre at 2.5 megavolts per centimetre). We find that the van der Waals gap between strontium-titanium-oxide dielectrics and 2D semiconductors mitigates the unfavourable fringing-induced barrier-lowering effect resulting from the use of ultrahigh-κ dielectrics4. Typical short-channel transistors made of scalable molybdenum-disulfide films by chemical vapour deposition and strontium-titanium-oxide dielectrics exhibit steep subthreshold swings down to about 70 millivolts per decade and on/off current ratios up to 107, which matches the low-power specifications suggested by the latest International Roadmap for Devices and Systems5.

How to report and benchmark emerging field-effect transistors

Abstract: Emerging low-dimensional nanomaterials have been studied for decades in device applications as field-effect transistors (FETs). However, properly reporting and comparing device performance has been challenging due to the involvement and interlinking of multiple device parameters. More importantly, the interdisciplinarity of this research community results in a lack of consistent reporting and benchmarking guidelines. Here we report a consensus among the authors regarding guidelines for reporting and benchmarking important FET parameters and performance metrics. We provide an example of this reporting and benchmarking process for a two-dimensional (2D) semiconductor FET. Our consensus will help promote an improved approach for assessing device performance in emerging FETs, thus aiding the field to progress more consistently and meaningfully.

Large-Area Interfaces for Single-Molecule Label-free Bioelectronic Detection.

Abstract: Bioelectronic transducing surfaces that are nanometric in size have been the main route to detect single molecules. Though enabling the study of rarer events, such methodologies are not suited to assay at concentrations below the nanomolar level. Bioelectronic field-effect-transistors with a wide (μm2-mm2) transducing interface are also assumed to be not suited, because the molecule to be detected is orders of magnitude smaller than the transducing surface. Indeed, it is like seeing changes on the surface of a one-kilometer-wide pond when a droplet of water falls on it. However, it is a fact that a number of large-area transistors have been shown to detect at a limit of detection lower than femtomolar; they are also fast and hence innately suitable for point-of-care applications. This review critically discusses key elements, such as sensing materials, FET-structures, and target molecules that can be selectively assayed. The amplification effects enabling extremely sensitive large-area bioelectronic sensing are also addressed.

Dual-gated single-molecule field-effect transistors beyond Moore’s law

Abstract: As conventional silicon-based transistors are fast approaching the physical limit, it is essential to seek alternative candidates, which should be compatible with or even replace microelectronics in the future. Here, we report a robust solid-state single-molecule field-effect transistor architecture using graphene source/drain electrodes and a metal back-gate electrode. The transistor is constructed by a single dinuclear ruthenium-diarylethene (Ru-DAE) complex, acting as the conducting channel, connecting covalently with nanogapped graphene electrodes, providing field-effect behaviors with a maximum on/off ratio exceeding three orders of magnitude. Use of ultrathin high-k metal oxides as the dielectric layers is key in successfully achieving such a high performance. Additionally, Ru-DAE preserves its intrinsic photoisomerisation property, which enables a reversible photoswitching function. Both experimental and theoretical results demonstrate these distinct dual-gated behaviors consistently at the single-molecule level, which helps to develop the different technology for creation of practical ultraminiaturised functional electrical circuits beyond Moore's law.

Ferroelectric Field‐Effect‐Transistor Integrated with Ferroelectrics Heterostructure

Abstract: To address the demands of emerging data‐centric computing applications, ferroelectric field‐effect transistors (Fe‐FETs) are considered the forefront of semiconductor electronics owing to their energy and area efficiency and merged logic–memory functionalities. Herein, the fabrication and application of an Fe‐FET, which is integrated with a van der Waals ferroelectrics heterostructure (CuInP2S6/α‐In2Se3), is reported. Leveraging enhanced polarization originating from the dipole coupling of CIPS and α‐In2Se3, the fabricated Fe‐FET exhibits a large memory window of 14.5 V at VGS = ±10 V, reaching a memory window to sweep range of ≈72%. Piezoelectric force microscopy measurements confirm the enhanced polarization‐induced wider hysteresis loop of the double‐stacked ferroelectrics compared to single ferroelectric layers. The Landau–Khalatnikov theory is extended to analyze the ferroelectric characteristics of a ferroelectric heterostructure, providing detailed explanations of the hysteresis behaviors and enhanced memory window formation. The fabricated Fe‐FET shows nonvolatile memory characteristics, with a high on/off current ratio of over 106, long retention time (>104 s), and stable cyclic endurance (>104 cycles). Furthermore, the applicability of the ferroelectrics heterostructure is investigated for artificial synapses and for hardware neural networks through training and inference simulation. These results provide a promising pathway for exploring low‐dimensional ferroelectronics.

Growth of high-quality semiconducting tellurium films for high-performance p-channel field-effect transistors with wafer-scale uniformity

Abstract: Abstract Achieving high-performance p-type semiconductors has been considered one of the most challenging tasks for three-dimensional vertically integrated nanoelectronics. Although many candidates have been presented to date, the facile and scalable realization of high-mobility p-channel field-effect transistors (FETs) is still elusive. Here, we report a high-performance p-channel tellurium (Te) FET fabricated through physical vapor deposition at room temperature. A growth route involving Te deposition by sputtering, oxidation and subsequent reduction to an elemental Te film through alumina encapsulation allows the resulting p-channel FET to exhibit a high field-effect mobility of 30.9 cm 2 V −1 s −1 and an I ON/OFF ratio of 5.8 × 10 5 with 4-inch wafer-scale integrity on a SiO 2 /Si substrate. Complementary metal-oxide semiconductor (CMOS) inverters using In-Ga-Zn-O and 4-nm-thick Te channels show a remarkably high gain of ~75.2 and great noise margins at small supply voltage of 3 V. We believe that this low-cost and high-performance Te layer can pave the way for future CMOS technology enabling monolithic three-dimensional integration.

Side-Chain Engineering of Conjugated Polymers for High-Performance Organic Field-Effect Transistors.

Abstract: Past decades have witnessed the rapid development of conjugated polymers because of their promising semiconducting properties and applications in organic field-effect transistors (OFETs). Recent studies have shown that side-chain engineering of conjugated polymers is an efficient strategy to increase semiconducting performance. This Perspective focuses on the side-chain modulation of conjugated polymers and evaluating their effects on the performance of OFETs. The challenges and potential applications of functional high-performance OFETs through side-chain engineering are also discussed.

Effects of High-Pressure Annealing on the Low-Frequency Noise Characteristics in Ferroelectric FET

Abstract: In this work, the low-frequency noise (LFN) characteristics of hafnium-zirconium oxide (HZO) ferroelectric field-effect transistors (FeFETs) with and without high-pressure forming gas annealing (HPA) treatment are investigated. The origin of $1/ {f}$ noise in the FeFET without HPA is changed from carrier number fluctuation to Hooge’s mobility fluctuation after wake-up due to the remote phonon scattering from the polarized HZO. Also, Hooge’s parameter is increased by the program/erase (P/E) cycling-induced stress. On the contrary, only the correlated mobility fluctuation is increased after the wake-up in the FeFET with HPA. Furthermore, the LFN of the FeFET with HPA shows robustness to P/E cycling-induced stress after the wake-up, showing superb endurance performance.

Single-Atom Pt-Functionalized Ti3C2Tx Field-Effect Transistor for Volatile Organic Compound Gas Detection.

Abstract: MXenes have shown exceptional electrochemical properties and demonstrate great promise in chemiresistive gas analysis applications. However, their sensing applications still face low sensitivity and specificity, slow response, and poor stability among the many challenges. Herein, a novel synthetic approach is reported to produce single-atom Pt (Pt SA)-implanted Ti3C2Tx MXene nanosheets as the sensing channel in field-effect transistor (FET) gas sensors. This is a pioneer study of single-atom catalysts loaded on MXene nanosheets for gas detection, which demonstrates that Pt SA can greatly enhance the sensing performance of pristine Ti3C2Tx. The Pt SA-Ti3C2Tx sensor exhibits high sensitivity and specificity toward ppb level (a low detection limit of 14 ppb) triethylamine (TEA) with good multicycle sensing performance. Moreover, the mechanism study and density functional theory (DFT) simulation show that the chemical sensitization effect and TEA adsorption enhancement from highly catalytic and uniformly distributed Pt SA lead to the enhanced sensing performances. This work presents a new prospect of single-atom catalysts for gas analysis applications, which will promote the development of cutting-edge sensing techniques for gas detection for public health and environment.

Two-Dimensional MoSi₂N₄: An Excellent 2-D Semiconductor for Field-Effect Transistors

Abstract: We report the performance of field-effect transistors (FETs), comprised of mono-layer of recently synthesized layered two-dimensional MoSi2N_4 as channel material, using the first principles quantum transport simulations. The devices' performance is assessed as per the International Roadmap for Devices and Systems (IRDS) 2020 roadmap for the year 2034 and compared to advanced silicon-based FETs, carbon nanotube-based FETs, and other promising two-dimensional materials based FETs. Finally, we estimate the figure of merits of a combinational and a sequential logic circuit based on our double gate devices and benchmark against promising alternative logic technologies. The performance of our devices and circuits based on them are encouraging, and competitive to other logic alternatives.

Fast Read-After-Write and Depolarization Fields in High Endurance n-Type Ferroelectric FETs

Abstract: Ferroelectric field-effect transistors (FeFETs) based on HfO2 are promising for low-power and high-speed non-volatile memory devices. However, most reported FeFETs show limited write endurance and significant read-after-write delay due to parasitic charge trapping. Here we show that n-type FeFETs with SiNx interfacial layer and high write endurance also exhibit immediate read-after-write behavior due to negligible charge trapping. This overcomes one of the major challenges faced by FeFET technologies today.

Multifunctional Half-Floating-Gate Field-Effect Transistor Based on MoS2-BN-Graphene van der Waals Heterostructures.

Abstract: Multifunctional electronic devices that combine logic operation and data storage functions are of great importance in developing next-generation computation. The recent development of van der Waals (vdW) heterostructures based on various two-dimensional (2D) materials have brought exceptional opportunities in designing novel electronic devices. Although various 2D-heterostructure-based electronic devices have been reported, multifunctional devices that can combine logic operations and data storage functions are still quite rare. In this work, we design and fabricate a half-floating-gate field-effect transistor based on MoS2-BN-graphene vdW heterostuctures, which can be used for logic operations as a MOSFET, nonvolatile memory as a floating-gate MOSFET (FG-MOSFET), and rectification as a diode. These results could lay the foundation for various applications based on 2D vdW heterostuctures and inspire the design of next-generation computation beyond the von Neumann architecture.

Performance Limit of Ultrathin GaAs Transistors.

Abstract: High-electron-mobility group III-V compounds have been regarded as a promising successor to silicon in next-generation field-effect transistors (FETs). Gallium arsenide (GaAs) is an outstanding member of the III-V family due to its advantage of both good n- and p-type device performance. Monolayer (ML) GaAs is the limit form of ultrathin GaAs. Here, a hydrogenated ML GaAs (GaAsH2) FET is simulated by ab initio quantum-transport methods. The n- and p-type ML GaAsH2 metal-oxide-semiconductor FETs (MOSFETs) can well satisfy the on-state current, delay time, power dissipation, and energy-delay product requirements of the International Technology Roadmap for Semiconductors until the gate length is scaled down to 3/4 and 3/5 nm for the high-performance/low-power applications, respectively. Therefore, ultrathin GaAs is a prominent channel candidate for devices in the post-Moore era. The p-type ML GaAsH2 MOSFETs with a 2% uniaxially compressive strain and the unstrained n-type counterparts have symmetrical performance for the high-performance application, making ultrathin GaAs applicable for complementary MOS integrated circuits.

Nanomaterial-Based Biosensors using Field-Effect Transistors: A Review

Abstract: Field-effect transistor biosensors (Bio-FET) have attracted great interest in recent years owing to their distinctive properties like high sensitivity, good selectivity, and easy integration into portable and wearable electronic devices. Bio-FET performance mainly relies on the constituent components such as the bio-recognition layer and the transducer, which ensures device stability, sensitivity, and lifetime. Nanomaterial-based Bio-FETs are excellent candidates for biosensing applications. This review discusses the basic concepts, function, and working principles of Bio-FETs, and focuses on the progress of recent research in Bio-FETs in the sensing of neurotransmitters, glucose, nucleic acids, proteins, viruses, and cancer biomarkers using nanomaterials. Finally, challenges in the development of Bio-FETs, as well as an outlook on the prospects of nano Bio-FET-based sensing in various fields, are discussed.

Recent progress in organic field‐effect transistor‐based chem/bio‐sensors

Abstract: Recent decades have witnessed the huge successes of organic field-effect transistors (OFETs) and their applications. Among them, OFET-based sensors have shown promising applications in the field of food safety, industrial security, environmental, and health monitoring. This is due to their advantages in solution processability, flexibility, light weight, and variety in molecular design. This review highlights recent progress in OFET-based chemical and biological sensors in gas and liquid phase, especially for the past 5 years. The analytes range from small molecules to large biomolecules. The optimizations of OFET devices for sensors, including the semiconducting layers, dielectric layers, electrodes, and their interfaces etc., are illustrated. And their relationships with sensing parameters (sensitivity, selectivity, and response time) as well as the sensing mechanisms are given. Finally, the remaining challenges are discussed. We expect that this review can offer inspiration for future design of OFET-based sensors.

Dielectric‐Modulated Biosensing with Ultrahigh‐Frequency‐Operated Graphene Field‐Effect Transistors

Abstract: Owing to their excellent electrical properties and chemical stability, graphene field‐effect transistors (Gr‐FET) are extensively studied for biosensing applications. However, hinging on surface interactions of charged biomolecules, the sensitivity of Gr‐FET is hampered by ionic screening under physiological conditions with high salt concentrations up to frequencies as high as MHz. Here, an electrolyte‐gated Gr‐FET in reflectometry mode at ultrahigh frequencies (UHF, around 2 GHz), where the ionic screening is fully cancelled and the dielectric sensitivity of the device allows the Gr‐FET to directly function in high‐salt solutions, is configured. Strikingly, by simultaneous characterization using electrolyte gating and UHF reflectometry, the developed graphene biosensors offer unprecedented capability for real‐time monitoring of dielectric‐specified biomolecular/cell interactions/activities, with superior limit of detection compared to that of previously reported nanoscale high‐frequency sensors. These achievements highlight the unique potential of ultrahigh‐frequency operation for unblocking the true potential of graphene biosensors for point‐of‐care diagnostic.

Quantization, gate dielectric and channel length effect in double-gate tunnel field-effect transistor

Abstract: In this work, we investigate the effects of changing device parameters such as channel length and gate dielectric of n-type double gate (DG) silicon tunneling field effect transistor (TFET). As the quantization effects can alter the device performance, our objective is to minimize the effect of it on gate capacitance. Device sub-threshold slope (SS), threshold voltage and ION/IOFF the ratio are also considered to find the performance of the device. We find that DG TFET with the short channel length, high gate dielectric material, and material with effective mass equal to or more than 0.04 mo (mo is free electron mass) shows promising performance. SS of TFET is much less than 60 mV/dec, which is the limiting factor of a conventional MOSFET. The materials having an effective mass of electrons less than 0.04 mo shows step-like behaviors, which reduce the gate capacitance. As a result, the control over the gate decreases and increases the short channel effect. Our optimized device shows that for high dielectric constant gate materials, SS is 33 mV/dec, the threshold voltage is 0.71 V and ION/IOFF ratio is 109 .

Recent progress in single-molecule transistors: their designs, mechanisms and applications

Abstract: Single-molecule field-effect transistors (FETs) are the key building blocks of electronic circuits and a unique platform for studying physical mechanisms. Here, the designs, mechanisms and applications of single-molecule FETs are summarized.

Hybrid Nanocomposites of All‐Inorganic Halide Perovskites with Polymers for High‐Performance Field‐Effect‐Transistor‐Based Photodetectors: An Experimental and Simulation Study

Abstract: All‐inorganic halide perovskites have recently emerged as a promising candidate for new‐generation optoelectronics. The device performance of solution‐processed photodetectors critically depends on the surface morphology and film features, however, the behind mechanism is not clear till now. In this paper, a feasible method for surface‐passivating all‐inorganic halide perovskites with poly(3‐hexylthiophene) (P3HT) as the photoactive layer for field‐effect transistor (FET)‐based photodetectors is presented, and the underlying mechanisms to enhance device performance are investigated by experimental and simulating study. As the result, a high photoresponsivity of 469 A W−1 with a specific detectivity of 1.34 × 1014 Jones is obtained under 0.4 mW cm−2 405 nm illumination for FET‐based photodetector Au(S&D)/CsPbBr3:P3HT/PMMA/Al(G). This experimental and simulating study shows that the enhanced‐performance origins from improving the photogenerated charge carriers transportation and suppressing the dark current through the photodetectors.

Hydrogen-terminated diamond MOSFETs on (0 0 1) single crystal diamond with state of the art high RF power density

Abstract: Abstract Diamond field-effect transistor (FET) has great application potential for high frequency and high power electronic devices. In this work, diamond FETs were fabricated on (0 0 1) single crystal diamond with homoepitaxial layer. The nitrogen impurity content in the homoepitaxial layer is greatly decreased as measured by the Raman and photoluminescence spectra. The diamond field effect transistor with 100 nm Al2O3 as gate dielectric shows ohomic contact resistance of 35 Ω . mm, maximum drain saturation current density of 500 mA/mm, and maximum transconductance of 20.1 mS/mm. Due to the high quality of Al2O3 gate dielectric and single crystal diamond substrate, the drain work voltage of −58 V is achieved for the diamond FETs. A continuous wave output power density of 4.2 W/mm at 2 GHz is obtained. The output power densities at 4 and 10 GHz are also improved and achieve 3.1 and 1.7 W/mm, respectively. This work shows the application potential of single crystal diamond for high frequency and high power electronic devices.

Mixed-Dimensional 1D/2D van der Waals Heterojunction Diodes and Transistors in the Atomic Limit.

Abstract: Inverting a semiconducting channel is the basis of all field-effect transistors. In silicon-based metal-oxide-semiconductor field-effect transistors (MOSFETs), a gate dielectric mediates this inversion. Access to inversion layers may be granted by interfacing ultrathin low-dimensional semiconductors in heterojunctions to advance device downscaling. Here we demonstrate that monolayer molybdenum disulfide (MoS2) can directly invert a single-walled semiconducting carbon nanotube (SWCNT) transistor channel without the need for a gate dielectric. We fabricate and study this atomically thin one-dimensional/two-dimensional (1D/2D) van der Waals heterojunction and employ it as the gate of a 1D heterojunction field-effect transistor (1D-HFET) channel. Gate control is based on modulating the conductance through the channel by forming a lateral p-n junction within the CNT itself. In addition, we observe a region of operation exhibiting a negative static resistance after significant gate tunneling current passes through the junction. Technology computer-aided design (TCAD) simulations confirm the role of minority carrier drift-diffusion in enabling this behavior. The resulting van der Waals transistor architecture thus has the dual characteristics of both field-effect and tunneling transistors, and it advances the downscaling of heterostructures beyond the limits of dangling bonds and epitaxial constraints faced by III-V semiconductors.

Ultrasensitive and Selective Bacteria Sensors Based on Functionalized Graphene Transistors

Abstract: We propose here a graphene biosensor based on the field-effect transistor (FET) architecture for continuous and real-time monitoring of bacteria, with beneficial features including facile operation, low-cost, selectivity, and high sensitivity. Our sensing device consists of the chemical-vapor-deposition (CVD) graphene monolayer, functionalized by the phage tail spike proteins (TSPs) that form specific binding sites to capture E. coli bacteria. We have investigated effects of surface functionalization and bacteria binding on the conductance of atomically thin graphene that determines transfer characteristics of a graphene FET (GFET). We have experimentally demonstrated that the concentration of E. coli bacteria can be selectively and accurately detected (at the single bacterium level) by a TSP-functionalized GFET. The proposed graphene biosensor may be of great interest for rapid, efficient detection of bacterial pathogens that could potentially pose a severe threat to human, animal, or plant health.

Pursuing High‐Performance Organic Field‐Effect Transistors through Organic Salt Doping

Abstract: Doping is an effective strategy for controlling the charge density and device performance of thin‐film electronics. Herein, a new doping system is reported for organic electronics using the organic salt p‐dopant N,N‐dimethylanilinium tetrakis(pentafluorophenyl)borate (DTB) to significantly improve the device performance of indacenodithiophene‐co‐benzothia‐diazole (IDT‐BT) organic field‐effect transistors (OFETs). With optimized doping ratios, the hole mobility increases almost fourfold from 0.32 to 1.15 cm2 V–1 s–1 and the threshold voltage reduces from −38 to 0 V. Moreover, systematical electrical characterizations demonstrate that the contact resistance and activation energy dramatically reduce in the doped devices. Such reductions are ascribed to the shift of the Fermi energy level closer to the transport level and the lowered density of trap states in doped semiconductors, as revealed by ultraviolet photoelectron spectroscopy and low‐frequency noise measurements, respectively. This study also demonstrates that the trap density increases when the doping ratio is high, explaining the device performance degradation at high doping ratios. This is the first time that DTB organic salt is used as an efficient dopant to improve the performance of OFETs, demonstrating a promising route for employing organic salt dopants to achieve high‐performance OFETs.