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The debye length is a measure of the distance over which the electric field of a charged particle decays in an electrolyte solution. If the binding of the analyte to the surface of the transducer is too far away from the surface, the electric field to the analyte may decay over a distance greater than the debye length thereby reducing the sensitivity of the measurement. In this context, this study has developed a simple one‐step protein immobilization strategy to covalently attach proteins on the sensor surface. Our binding strategy, which uses hydrogen peroxide (H2O2) ensures that the analyte is attached as close as possible to the transducer surface. This study evaluates our findings by comparing our strategy with silane chemistry and elucidating the debye length effects with colorimetric assays and field effect devices. Additionally, as a case study, we also evaluated the performance of our methodology for the detection of glucose oxidation by a field effect device. Overall, the developed immobilization strategy avoids the effects of the debye length and improves the performance of the biosensor. [ABSTRACT FROM AUTHOR]

Transition metal dichalcogenides (TMDC) exhibit highly superior electrical properties and are typically obtained through mechanical exfoliation. This method has significant limitations, however, such as patterning issues and non‐uniformity, which hinder their application in integrated circuits as transistors and array pixel displays. To overcome these challenges, various large‐scale deposition methods have been developed. In this review, we introduce five major methods for TMDC deposition: chemical vapor deposition, physical vapor deposition, atomic layer deposition, pulsed laser deposition, and ink‐jet printing. An overview of each method is provided in the following order: surface analysis, electrical characteristics, and limitations of each method are discussed. Furthermore, we present three key strategies for an advanced device fabrication using the discussed deposition methods. By implementing these strategies, we can accelerate the development of highly crystalline and scalable TMDC thin films, which are essential for producing advanced electronic devices with improved performance. Owing to recent technological advancements, TMDC devices have the potential to become the leading material for next‐generation semiconductor devices. These devices can be specifically designed and optimized for innovative applications. [ABSTRACT FROM AUTHOR]

We report on the formation of the field-effect transistor based on a polyyne–polyene structure. Polyvinylidene chloride (PVDC) drop casting and its subsequent dehydrochlorination in KOH solution allowed for the formation of porous polyyne–polyene material, which was analyzed via transmission electron microscopy, Fourier-transform infrared spectroscopy, and Raman spectroscopy, revealing the presence of sp- and sp2-hybridized chained fragments in the structure. The polyyne–polyene-based field-effect transistor showed a transconductance of 3.2 nA/V and a threshold voltage of −0.3 V. The obtained results indicate that polyyne–polyene-based transistors can be used as discrete elements of molecular electronics and that subsequent studies can be aimed toward the development of selective polyyne–polyene-based gas sensors with tunable sensitivity. [ABSTRACT FROM AUTHOR]

In this work, we present results on the growth of centimeter-scale pentacene crystals using the physical vapor transport method in a dual-temperature zone horizontal furnace. It was established that intensive crystal growth processes occurred in transition regions with sudden temperature changes, while crystal growth was practically not observed in regions with slightly varying temperatures. During crystal growth, co-precipitating golden needle-like crystals reaching lengths of more than 10 mm were obtained. Using the method of single-crystal X-ray diffraction at 85 and 293 K for dark-blue lamellar pentacene crystals, the crystal structure was refined in a triclinic system with sp.gr. P 1 ¯ . It was established that the golden needle crystals consisted of molecules of the pentacene derivative—5,14-pentacenedione, the crystal structure of which was solved for the first time in a rhombic system with sp.gr. P212121. The absorption and luminescence spectra of pentacene and 5,14-pentacenedione in toluene solutions were obtained and analyzed. The electrical properties of the prepared pentacene thin films and single crystals grown under physical vapor transport conditions were evaluated by fabricating and characterizing field-effect transistors (FETs). It was shown that the presence of impurities in the commercial pentacene material had a significant effect on the morphological quality of thin polycrystalline films and noticeably reduced the hole mobility. [ABSTRACT FROM AUTHOR]

In recent years, field-effect transistors (FETs) have been very promising for biosensor applications due to their high sensitivity, real-time applicability, scalability, and prospect of integrating measurement system on a chip. Non-carbon 2D materials, such as transition metal dichalcogenides (TMDCs), hexagonal boron nitride (h-BN), black phosphorus (BP), and metal oxides, are a group of new materials that have a huge potential in FET biosensor applications. In this work, we review the recent advances and remarkable studies of non-carbon 2D materials, in terms of their structures, preparations, properties and FET biosensor applications. We will also discuss the challenges facing non-carbon 2D materials-FET biosensors and their future perspectives.

Organic frameworks (OFs) offer a novel strategy for assembling organic semiconductors into robust networks that facilitate transport, especially the covalent organic frameworks (COFs). However, poor electrical conductivity through covalent bonds and insolubility of COFs limit their practical applications in organic electronics. It is known that the two-dimensional intralayer π∙∙∙π transfer dominates transport in organic semiconductors. However, because of extremely labile inherent features of noncovalent π∙∙∙π interaction, direct construction of robust frameworks via noncovalent π∙∙∙π interaction is a difficult task. Toward this goal, we report a robust noncovalent π∙∙∙π interaction-stacked organic framework, namely πOF, consisting of a permanent three-dimensional porous structure that is held together by pure intralayer noncovalent π∙∙∙π interactions. The elaborate porous structure, with a 1.69-nm supramaximal micropore, is composed of fully conjugated rigid aromatic tetragonal-disphenoid-shaped molecules with four identical platforms. πOF shows excellent thermostability and high recyclability and exhibits self-healing properties by which the parent porosity is recovered upon solvent annealing at room temperature. Taking advantage of the long-range π∙∙∙π interaction, we demonstrate remarkable transport properties of πOF in an organic-field-effect transistor, and the mobility displays relative superiority over the traditional COFs. These promising results position πOF in a direction toward porous and yet conductive materials for high-performance organic electronics.

This paper presents the development of a novel micro force sensor based on a laterally movable gate field-effect transistor (LMGFET). A precise electrical model is proposed for the performance evaluation of small-scale LMGFET devices and exhibits improved accuracy in comparison with previous models. A novel sandwich structure consisting of a gold cross-axis decoupling gate array layer and two soft photoresistive SU-8 layers is utilized. With the proposed dual-differential sensing configuration, the output current of the LMGFET lateral operation under vertical interference is largely eliminated, and the relative output error of the proposed sensor decreases from 4.53% (traditional differential configuration) to 0.01%. A practicable fabrication process is also developed and simulated for the proposed sensor. The proposed LMGFET-based force sensor exhibits a sensitivity of 4.65 µA·nN−1, which is comparable with vertically movable gate field-effect transistor (VMGFET) devices, but has an improved nonlinearity of 0.78% and a larger measurement range of ±5.10 µN. These analyses provide a comprehensive design optimization of the electrical and structural parameters of LMGFET devices and demonstrate the proposed sensor’s excellent force-sensing potential for biomedical micromanipulation applications.

Abstract Detecting physiological levels of neurotransmitters in biological samples can advance our understanding of brain disorders and lead to improved diagnostics and therapeutics. However, neurotransmitter sensors for real-world applications must reliably detect low concentrations of target analytes from small volume working samples. Herein, a platform for robust and ultrasensitive detection of dopamine, an essential neurotransmitter that underlies several brain disorders, based on graphene multitransistor arrays (gMTAs) functionalized with a selective DNA aptamer is presented. High-yield scalable methodologies optimized at the wafer level were employed to integrate multiple graphene transistors on small-size chips (4.5 × 4.5 mm). The multiple sensor array configuration permits independent and simultaneous replicate measurements of the same sample that produce robust average data, reducing sources of measurement variability. This procedure allowed sensitive and reproducible dopamine detection in ultra-low concentrations from small volume samples across physiological buffers and high ionic strength complex biological samples. The obtained limit-of-detection was 1 aM (10–18) with dynamic detection ranges spanning 10 orders of magnitude up to 100 µM (10–8), and a 22 mV/decade peak sensitivity in artificial cerebral spinal fluid. Dopamine detection in dopamine-depleted brain homogenates spiked with dopamine was also possible with a LOD of 1 aM, overcoming sensitivity losses typically observed in ion-sensitive sensors in complex biological samples. Furthermore, we show that our gMTAs platform can detect minimal changes in dopamine concentrations in small working volume samples (2 µL) of cerebral spinal fluid samples obtained from a mouse model of Parkinson’s Disease. The platform presented in this work can lead the way to graphene-based neurotransmitter sensors suitable for real-world academic and pre-clinical pharmaceutical research as well as clinical diagnosis.

The features of Nanotube Carbon (CNT) are fascinating to study due to their unique structural and electrical capabilities. The small structure of CNT in Field-Effect Transistor technology can produce a smaller device with a better performance. This work implemented the Taguchi method to optimize the Carbon Nanotube Field-Effect Transistor (CNTFET). The Minitab 19 software was used to carry out the Taguchi method analysis. Three design parameters (CNT’s diameter, pitch, and the number of CNT) with three sizes were chosen to improve the CNTFET capabilities. L27 orthogonal array and signal-to-noise (SNR) were used to collect and analyze the data. The result from the Taguchi method was validated using ANOVA. The analysis results displayed the best combination of the three design parameters that produced the optimum performance in terms of high-power and low-power application. The most dominant design parameter that affected the CNTFET’s current characteristics was the CNT diameter with 59.93%, 96.15% and 99.14% towards on-current (Ion), off-current (Ioff) and current ratio (Ion/Ioff), respectively. The device can be further optimized by identifying the most dominant structure in CNTFET. Eventually, the CNTFET devices can be enhanced in terms of high-power and low-power applications. [ABSTRACT FROM AUTHOR]

The SARS-CoV-2 pandemic has triggered many studies worldwide in the area of biosensors, leading to innovative approaches for the quantitative assessment of COVID-19. A nanostructured field-effect transistor (FET) is one type of device shown to be ultrasensitive for virus determination. FETs can be used as transducers to analyze changes in electrical current caused by the bonding of viral molecules to the surface of the semiconducting nanomaterial layer of the FETs. Although nano-transistors require simple setups amenable to be miniaturized for point-of-care diagnostic of COVID-19, this type of sensor usually has limited sensitivity in biological fluids. The reason behind this is the shortened screening length in the presence of high ionic strength solutions. In the frame of this study, we propose a methodology consisting of the FET surface modification with a hydrogel based on the star-shaped polyethylene glycol (starPEG), which hosts specific antibodies against SARS-CoV-2 spike protein in its porous structure. The deposition of the hydrogel increases the effective Debye length, preserving the biosensor's sensitivity. We demonstrate the capability of silicon nanonet-based FETs to detect viral antigens and cultured viral particles in phosphate-buffered saline (PBS) as well as in human-purified saliva. Finally, we discriminated between positive and negative patients' nasopharyngeal swab samples. [ABSTRACT FROM AUTHOR]

Compared with traditional silicon materials, wide-band gap semiconductors are more suitable for making high voltage, high-frequency and high-power semiconductor devices, and are considered to be the key role of material innovation in the post-Moore era. Single-crystal diamond (SCD) has superiorities of wide-band gap, extremely high thermal conductivity and high mobility, and is expected to develop high-power, high-frequency electronic devices. However, the limitation of SCD wafer size and ultra-expensive price obstructed its promotion. After a long-time exploration, heteroepitaxy technology is recognized as an effective approach to obtain high-quality and large-size SCD wafer. This review introduces the development of heteroepitaxial SCD in detail, in aspects of substrate selection, growth mechanism and quality improvement. Furthermore, the investigations of field-effect transistors and diodes based on heteroepitaxial SCD are summarized, indicating the great potential of heteroepitaxial SCD in electronic device field. Finally, the challenges of heteroepitaxial technology are pointed out, and the potential applications are anticipated. [ABSTRACT FROM AUTHOR]

Two‐dimensional (2D) materials are atomically thin materials that show quantum confinement effect. They have been studied as promising materials for field‐effect transistors (FETs). The fabrication of an FET mainly concerns how to deposit metal electrodes and dielectrics onto the 2D material channel. And conventional fabrication processes are not optimized for novel applications of 2D FETs. This review aims to introduce recent studies regarding novel electrodes and dielectrics for 2D FETs. The devices made by these approaches show comparable performance to conventional FETs. And they feature new applications and easy fabrication. This review covers the topics in two sections: evaporation‐free electrodes and nonoxide dielectrics. The former covers electrodes prepared without direct deposition of metals using evaporators or sputters. The latter encompasses alternatives to oxide dielectrics. These topics would be beneficial to realize the intrinsic properties of 2D materials and to assist fundamental research with prototyping FETs on a tabletop. [ABSTRACT FROM AUTHOR]

Various steep-slope devices based on novel structures and mechanisms garnered considerable attention for their potential in ultra-low power logic applications. In this work, a novel steep-slope negative quantum capacitance field-effect transistor (NQCFET) with molybdenum disulfide (MoS2)-integrated gate stack was realized by theoretical analysis and experimental evaluation. By combining the MoS2 equivalent capacitance model calibrated with experimental results, the NQCFET device model is further established. The results demonstrated that the optimized MoS2-integrated NQCFET can achieve a subthreshold swing (SS) of sub-60 mV/dec over a current range of 5 decades, with the minimum SS reaching 29 mV/dec, indicating the remarkable potential of MoS2-integrated NQCFETs for ultra-low power applications. [ABSTRACT FROM AUTHOR]

The synaptic devices based on various electronic materials have been widely investigated to realize functions of artificial information processing with low power consumption. In this work, a novel CVD graphene field-effect transistor is fabricated with ionic liquid gate to study the synaptic behaviors based on the electrical-double-layer mechanism. It is found that the excitative current is enhanced with the pulse width, voltage amplitude and frequency. With different situations of the applied pulse voltage, the inhibitory and excitatory behaviors are successfully simulated, at the same time the short-term memory is also realized. The corresponding ions migration and charge density variation are analyzed in the different time segments. This work provides the guidance for the design of artificial synaptic electronics with ionic liquid gate for low-power computing application. [ABSTRACT FROM AUTHOR]

A bio-inspired conduction mode in silicon-based field-effect transistors was studied here using the frequency-dependent reconfiguration principle in a size-reduced circuit architecture. Analog circuits comprising neuromorphic and reconfigurable behavior were analyzed across their physical quantities using a set of equations governing circuit performance. Practical examples were built, analyzed, and discussed from a phenomenological viewpoint. Upon exploiting their reconfiguration properties when semiconductor devices and passive components are interconnected, novel operating principles might inspire optimized signal processing and manufacturing facilities to design circular device-based complex systems. [ABSTRACT FROM AUTHOR]

The authors demonstrate improved switching voltage, retention, and endurance properties in HfZrOx (HZO)‐based n/p‐ferroelectric field‐effect transistors (FeFETs) via oxygen scavenging. Oxygen scavenging using titanium (Ti) in the gate stack successfully reduce the thickness of interfacial oxide between HZO and Si and the oxygen vacancy at the bottom interface of the HZO film. The n/p‐FeFETs with scavenging exhibit an immediate read‐after‐write with stable retention property and improved endurance property. In particular, n‐FeFET with scavenging exhibits excellent endurance property that does not show breakdown up to 1010 cycles. The charge trapping model in the n/p‐FeFETs is presented to explain why the effect of oxygen scavenging is more pronounced in n‐FeFET than in p‐FeFET. Finally, further switching voltage scaling potential is estimated by scavenging and HZO thickness scaling. It is believed that this work contributes to the development of low‐power FeFET and the understanding of FeFET operation. [ABSTRACT FROM AUTHOR]

Field-effect transistor (FET) is regarded as the most promising candidate for the next-generation biosensor, benefiting from the advantages of label-free, easy operation, low cost, easy integration, and direct detection of biomarkers in liquid environments. With the burgeoning advances in nanotechnology and biotechnology, researchers are trying to improve the sensitivity of FET biosensors and broaden their application scenarios from multiple strategies. In order to enable researchers to understand and apply FET biosensors deeply, focusing on the multidisciplinary technical details, the iteration and evolution of FET biosensors are reviewed from exploring the sensing mechanism in detecting biomolecules (research direction 1), the response signal type (research direction 2), the sensing performance optimization (research direction 3), and the integration strategy (research direction 4). Aiming at each research direction, forward perspectives and dialectical evaluations are summarized to enlighten rewarding investigations. [ABSTRACT FROM AUTHOR]

Using the metal–organic chemical vapor deposition technique, we synthesized a bilayer lateral heterostucture of MoS2 and WS2, each of which layers consist of alternately arranged nanostrips of MoS2 and WS2. Transmission electron microscope images exhibit a checked pattern contrast, reflecting the three distinct interlayer metal arrangements of Mo/Mo, W/Mo (Mo/W), and W/W stacking. Theoretical calculations based on the density functional theory elucidated that the bilayer lateral heterostructure of MoS2 and WS2 exhibits complexed type-II band edge alignments depending on the interlayer metal arrangement: The conduction band edge is located at the Mo atom in a Mo/Mo sector, while the valence band edge is located at the W atom in a W/W sector. According to the complexed band edge alignment, the field-induced carrier injection behavior in the bilayer heterosheet composed of MoS2 and WS2 strips shows gate-induced trans-dimensionality, where the accumulated carrier distributions continuously vary from zero- to two-dimensional based on the applied gate voltage. Tunable carrier dimensionality can be applicable for wide areas of electronics, such as quantum dot arrays with tunable dot–dot interaction. [ABSTRACT FROM AUTHOR]

Hexabenzocoronene (HBC) is a promising candidate due to its exclusive optical and electronic properties, high thermal stability, and chemical inertness. The proposed work explores the structural and electronic properties of HBC through various techniques, like TD-DFT (time-dependent) and DFT (density functional theory). The performance of HBC-based FETs and solar cells are also evaluated through simulation and experimentation. The results suggest that HBC can be a suitable one for both applications, with excellent charge transport properties and high carrier mobility in FETs and high-power conversion efficiency in solar cells. Furthermore, the environmental impact of HBC-based devices is investigated and compared it with conventional devices that use non-eco-friendly materials. Finally, HBC-based devices have a lower carbon footprint and offer a sustainable alternative to conventional devices. The study contributes the development of sustainable electronic devices and offers insights into the design and optimisation of future eco-friendly electronic materials. [ABSTRACT FROM AUTHOR]

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In this study, the logic‐in‐memory operations are demonstrated of ternary NAND and NOR logic gates consisting of double‐gated feedback field‐effect transistors. The component transistors reconfigure their operation modes into n‐ or p‐channel modes by adjusting the gate biases. The highly symmetrical operation between these operation modes with an excellent on‐current ratio of 1.03 enables three distinguishable and stable logic levels in the ternary logic gates. Moreover, the ternary logic gates maintain the three logic states for several tens to hundreds of seconds under zero‐bias condition. This study demonstrates that the ternary logic gates are promising candidates for next‐generation low‐power computing systems. [ABSTRACT FROM AUTHOR]

A theoretical model for simulating ionizing radiation effects on negative capacitance field-effect transistors (NCFETs) with a metal–ferroelectric–insulator–semiconductor (MFIS) structure was established. Based on the model, the effects of total ionizing dose (TID) and dose rate on the surface potential, ferroelectric capacitance, voltage amplification factor, and transfer characteristics of NCFETs were investigated. The simulation results demonstrated that, with the increase in total dose, the curves of surface potential versus gate voltage and driving current versus gate voltage shift left significantly, resulting in the point of voltage amplification shifting left. Meanwhile, with the increase in dose rate, the amplitude of both the surface potential and driving current decreases slightly. Meanwhile, the derived result indicated that relatively thin ferroelectric thickness can effectively reduce the effect of TID. It is expected that this model can be helpful for analyzing the radiation effects of NCFETs. [ABSTRACT FROM AUTHOR]

Micro RNAs (miRNAs) are 19–23 nucleotides-long non-coding RNA which have been identified as important biomarkers for many diseases, including cancers. Here, we report an ultrasensitive, highly specific, label-free, and without nucleic acid amplification (NAA) detection of miRNAs using paper-based single-walled carbon nanotubes (SWNTs) field-effect transistor (FET) biosensors. The strategy involved a two-step protocol starting with direct hybridization of the target miRNA with a specific RNA probe immobilized on SWNTs networks deposited on the paper substrate to generate the first response, followed by the recognition of the resulting RNA/miRNA duplexes with the Carnation Italian ringspot virus p19 protein (p19) in a size-dependent manner, giving the second electrical response that magnified the biosensor sensitivity. As a demonstration, we detected the miRNA-122a, a promising biomarker for the diagnosis of early-stage hepatocellular carcinoma (HCC) in various sample matrices, including phosphate buffers, human serum, and synthetic saliva. We achieved the lowest detection of 0.1 aM and a wide dynamic range of 0.1 aM–1 fM, that demonstrated its potential for rapid, facile, low-cost, and point-of-care detection of miRNAs for early cancer diagnosis.

Abstract The debye length is a measure of the distance over which the electric field of a charged particle decays in an electrolyte solution. If the binding of the analyte to the surface of the transducer is too far away from the surface, the electric field to the analyte may decay over a distance greater than the debye length thereby reducing the sensitivity of the measurement. In this context, this study has developed a simple one‐step protein immobilization strategy to covalently attach proteins on the sensor surface. Our binding strategy, which uses hydrogen peroxide (H2O2) ensures that the analyte is attached as close as possible to the transducer surface. This study evaluates our findings by comparing our strategy with silane chemistry and elucidating the debye length effects with colorimetric assays and field effect devices. Additionally, as a case study, we also evaluated the performance of our methodology for the detection of glucose oxidation by a field effect device. Overall, the developed immobilization strategy avoids the effects of the debye length and improves the performance of the biosensor.

The use of multimodal readout mechanisms next to label-free real-time monitoring of biomolecular interactions can provide valuable insight into surface-based reaction mechanisms. To this end, the combination of an electrolyte-gated field-effect transistor (EG-FET) with a fiber optic-coupled surface plasmon resonance (FO-SPR) probe serving as gate electrode has been investigated to deconvolute surface mass and charge density variations associated to surface reactions. However, applying an electrochemical potential on such gold-coated FO-SPR gate electrodes can induce gradual morphological changes of the thin gold film, leading to an irreversible blue-shift of the SPR wavelength and a substantial signal drift. We show that mild annealing leads to optical and electronic signal stabilization (20-fold lower signal drift than as-sputtered fiber optic gates) and improved overall analytical performance characteristics. The thermal treatment prevents morphological changes of the thin gold-film occurring during operation, hence providing reliable and stable data immediately upon gate voltage application. Thus, the readout output of both transducing principles, the optical FO-SPR and electronic EG-FET, stays constant throughout the whole sensing time-window and the long-term effect of thermal treatment is also improved, providing stable signals even after 1 year of storage. Annealing should therefore be considered a necessary modification for applying fiber optic gate electrodes in real-time multimodal investigations of surface reactions at the solid-liquid interface.

In this study, we demonstrate the generation and storage of random voltage values using a ring oscillator consisting of feedback field-effect transistors (FBFETs). This innovative approach utilizes the logic-in-memory function of FBFETs to extract continuous output voltages from oscillatory cycles. The ring oscillator exhibited uniform probability distributions of 51.6% for logic 0 and 48.4% for logic 1. The generation of analog voltages provides binary random variables that are stored for over 5000 s. This demonstrates the potential of the ring oscillator in advanced physical functions and true random number generator technologies.

Pseudohelical edge state (PHES) was proposed based on a staggered spin–orbit coupling (SOC) uniformly applied on graphene. In this work, we investigate the formation of the PHES and its edge-state transitions by the side potentials composed of a uniform SOC, an antiferromagnetic exchange field and a staggered electric field that are applied on the boundaries in zigzag graphene nanoribbon. The results reveal that the PHESs can also be achieved by the side potential of the antisymmetric uniform spin–orbit coupling, which is attributed to the fact that the opposite (same) sign of energies at the valleys $K$ and $K^{\prime}$ indicates the presence (absence) of the edge state. Based on this modulated mechanism, the PHES can be further transformed into two different types of the PHESs, spin-polarized antichiral edge states (AESs) and one-sided spin-polarized AESs, by modulating the applied direction and location of the side potentials. More strikingly, by utilizing these edge-state transitions, we propose a spin dual-channel or single-channel field-effect transistor that can be operated by a staggered electric field. Moreover, we confirm that the proposed transistor is robust against disorders, with the assistance of calculating the transmission.

Field-effect transistor (FET) biosensors can be used to measure the charge information carried by biomolecules. However, insurmountable hysteresis in the long-term and large-range transfer characteristic curve exists and affects the measurements. Noise signal, caused by the interference coefficient of external factors, may destroy the quantitative analysis of trace targets in complex biological systems. In this report, a “rectified signal” in the output characteristic curve, instead of the “absolute value signal” in the transfer characteristic curve, is obtained and analyzed to solve these problems. The proposed asymmetric Schottky barrier-generated MoS2/WTe2 FET biosensor achieved a 105 rectified signal, sufficient reliability and stability (maintained for 60 days), ultra-sensitive detection (10 aM) of the Down syndrome-related DYRK1A gene, and excellent specificity in base recognition. This biosensor with a response range of 10 aM–100 pM has significant application potential in the screening and rapid diagnosis of Down syndrome.

An analysis of the measured macroscopic withinwafer variations for threshold voltage (Vth) and on-current (Ion) over several technology generations (180 nm, 100 nm and 65 nm) is reported. It is verified that the dominant microscopic variations of the MOSFET device can be extracted quantitatively from these macroscopic variation data by applying the surface-potential compact model Hiroshima University STARC IGFET model 2 (HiSIM2), which is presently brought into industrial application. Only a small number of microscopic parameters, representing substrate doping (NSUBC), pocket-implantation doping (NSUBP), carrier-mobility degradation due to gate-interface roughness (MUESR1) and channel-length variation during the gate formation (XLD) are found sufficient to quantitatively reproduce the measured macroscopic within-wafer variations of Vth and Ion for all channel length Lg and all technology generations. Quantitative improvements from 180 nm to 65 nm are confirmed to be quite large for MUESR1 (about 70%) and Lmin(XLD) (55%) variations, related to the gate-oxide interface and the gate-stack structuring, respectively. On the other hand, doping-related technology advances, which are reflected by the variation magnitudes of NSUBC (30%) and NSUBP (25%), are found to be considerably smaller. Furthermore, specific combinations of extreme microscopic parameter-variation values are able to represent the boundaries of macroscopic fabrication inaccuracies for Vth and Ion. These combinations are found to remain identical, not only for all Lg of a given technology node, but also for all investigated technologies with minimum Lg of 180 nm, 100 nm and 65 nm.

Abstract Nano‐biosensors that are composed of recognition molecules and nanomaterials have been extensively utilized in disease diagnosis, health management, and environmental monitoring. As a type of nano‐biosensors, molecular specificity field‐effect transistor (FET) biosensors with signal amplification capability exhibit prominent advantages including fast response speed, ease of miniaturization, and integration, promising their high sensitivity for molecules detection and identification. With intrinsic characteristics of high stability and structural tunability, aptamer has become one of the most commonly applied biological recognition units in the FET sensing fields. This review summarizes the recent progress of FET biosensors based on aptamer functionalized nanomaterials in medical diagnosis and environmental monitoring. The structure, sensing principles, preparation methods, and functionalization strategies of aptamer modified FET biosensors were comprehensively summarized. The relationship between structure and sensing performance of FET biosensors was reviewed. Furthermore, the challenges and future perspectives of FET biosensors were also discussed, so as to provide support for the future development of efficient healthcare management and environmental monitoring devices.

Abstract The authors demonstrate improved switching voltage, retention, and endurance properties in HfZrOx (HZO)‐based n/p‐ferroelectric field‐effect transistors (FeFETs) via oxygen scavenging. Oxygen scavenging using titanium (Ti) in the gate stack successfully reduce the thickness of interfacial oxide between HZO and Si and the oxygen vacancy at the bottom interface of the HZO film. The n/p‐FeFETs with scavenging exhibit an immediate read‐after‐write with stable retention property and improved endurance property. In particular, n‐FeFET with scavenging exhibits excellent endurance property that does not show breakdown up to 1010 cycles. The charge trapping model in the n/p‐FeFETs is presented to explain why the effect of oxygen scavenging is more pronounced in n‐FeFET than in p‐FeFET. Finally, further switching voltage scaling potential is estimated by scavenging and HZO thickness scaling. It is believed that this work contributes to the development of low‐power FeFET and the understanding of FeFET operation.

Abstract In this study, the logic‐in‐memory operations are demonstrated of ternary NAND and NOR logic gates consisting of double‐gated feedback field‐effect transistors. The component transistors reconfigure their operation modes into n‐ or p‐channel modes by adjusting the gate biases. The highly symmetrical operation between these operation modes with an excellent on‐current ratio of 1.03 enables three distinguishable and stable logic levels in the ternary logic gates. Moreover, the ternary logic gates maintain the three logic states for several tens to hundreds of seconds under zero‐bias condition. This study demonstrates that the ternary logic gates are promising candidates for next‐generation low‐power computing systems.

Two-dimensional (2D) materials are considered attractive semiconducting layers for emerging field-effect transistors owing to their unique electronic and optoelectronic properties. Polymers have been utilized in combination with 2D semiconductors as gate dielectric layers in field-effect transistors (FETs). Despite their distinctive advantages, the applicability of polymer gate dielectric materials for 2D semiconductor FETs has rarely been discussed in a comprehensive manner. Therefore, this paper reviews recent progress relating to 2D semiconductor FETs based on a wide range of polymeric gate dielectric materials, including (1) solution-based polymer dielectrics, (2) vacuum-deposited polymer dielectrics, (3) ferroelectric polymers, and (4) ion gels. Exploiting appropriate materials and corresponding processes, polymer gate dielectrics have enhanced the performance of 2D semiconductor FETs and enabled the development of versatile device structures in energy-efficient ways. Furthermore, FET-based functional electronic devices, such as flash memory devices, photodetectors, ferroelectric memory devices, and flexible electronics, are highlighted in this review. This paper also outlines challenges and opportunities in order to help develop high-performance FETs based on 2D semiconductors and polymer gate dielectrics and realize their practical applications. [ABSTRACT FROM AUTHOR]

Owing to the simplicity, scalability, and cost-efficiency, solution-processable two-dimensional (2D) semiconductors have attracted great interest in electronic applications, especially as the channel material for field-effect transistors (FETs). Inkjet printing is a lithography-free technique to achieve drop-on-demand patterning of solution-processable 2D ink. However, thus far, inkjet-printed 2D FETs exhibit limited performance due to the coffee-ring effect and consequent discontinuity of the printed 2D material films. Here, we report high-performance and flexible inkjet-printed MoS2 FETs with high mobilities and high on/off ratios and their gas sensing applications. By preparing high-quality MoS2 ink comprised of MoS2 nanoplates using electrochemical exfoliation and then applying a binary solvent comprised of 2-butanol and isopropanol, the obtained ink was printed to form a continuous and relatively uniform MoS2 film, and high-performance printed MoS2 FETs were demonstrated, with mobilities of 11 cm2 V–1 s–1 and on/off ratios of 106. Furthermore, low-voltage gate modulation was achieved by applying an ion gel gate, and robust electrical performance under tensile strain was observed for the ion gel-gated MoS2 FETs printed on flexible substrates. As the printed MoS2 film is abundant in edge sites and sulfur vacancies, we further demonstrated our MoS2 FETs as high-performance gas sensors with a limit of detection of 10 ppb for NO2 and 0.5 ppm for NH3, together with a fast recovery rate. [ABSTRACT FROM AUTHOR]

A compact model able to predict the electrical read-out of field-effect biosensors based on two-dimensional (2D) semiconductors is introduced. It comprises the analytical description of the electrostatics including the charge density in the 2D semiconductor, the site-binding modeling of the barrier oxide surface charge, and the Stern layer plus an ion-permeable membrane, all coupled with the carrier transport inside the biosensor and solved by making use of the Donnan potential inside the ion-permeable membrane formed by charged macromolecules. This electrostatics and transport description account for the main surface-related physical and chemical processes that impact the biosensor electrical performance, including the transport along the low-dimensional channel in the diffusive regime, electrolyte screening, and the impact of biological charges. The model is implemented in Verilog-A and can be employed on standard circuit design tools. The theoretical predictions obtained with the model are validated against measurements of a MoS2 field-effect biosensor for streptavidin detection showing excellent agreement in all operation regimes and leading the way for the circuit-level simulation of biosensors based on 2D semiconductors. [ABSTRACT FROM AUTHOR]

Sulfur‐embedded polycyclic aromatic compounds have been used as building blocks for numerous organic semiconductors over the past few decades. While the success is based on thiophene‐containing compounds, aromatic compounds that contain thiepine, a sulfur‐containing seven‐membered‐ring arene, has been less well investigated. Here we report the synthesis and properties of π‐extended pyrrole‐fused heteropine compounds such as thiepine and oxepine. A π‐extended pyrrole‐fused thiepine exhibited a "pitched π‐stacking" structure in the crystal, and exhibited a high charge carrier mobility of up to 1.0 cm2 V−1 s−1 in single‐crystal field‐effect transistors. [ABSTRACT FROM AUTHOR]

The detection of lead ion (Pb2+) contamination in aqueous media is relevant for preventing endemic health issues as well as damage to cognitive and physical health. Existing home kit tests are unable to achieve clinically relevant sensitivity and specificity. Here, a label-free graphene field-effect transistor sensor for detecting Pb2+ at the femtomolar (fM) level, discriminating between confounding ions, is reported. The sensing principle is based on electrically monitoring Pb2+-binding-mediated conformational changes of a specific aptamer tethered to graphene, modeled through the Hills–Langmuir mechanism. A record sensitivitythrough a limit of detection of ∼61 fM, for Pb2+ was demonstrated. For model verification, specific discrimination of Pb2+ from other ions at the 1 picomolar (pM) level was shown. The reported work provides motivation for development of portable, label-free, point-of-care devices with both high specificity and sensitivity. [ABSTRACT FROM AUTHOR]

Pressure sensors based on field-effect transistor mechanism has received a lot of attention from researchers, which can effectively suppress low contrast and crosstalk effects. In this paper, we demonstrate a pressure sensor based on carbon nanotube field-effect transistor (CNTs-FET) and three-dimensional conformal force-sensitive top electrode with high sensitivity and easy integration. The high mobility field-effect transistor sensors were prepared using CNTs films with 99.9999% semiconductor concentration as the channel material. Conformal graphene nanowalls (GNWs) film on pyramidal micro-structure arrays worked as force-sensitive top electrode, the field-effect transistor sensor shows a sensitivity of 946.23 kPa−1 and 43.79 kPa−1 in the linear range of 0–30 Pa and 0.03–10 kPa, much higher than piezoresistive sensor (the sensitivity of about 377.73 kPa−1) and capacitive sensor (the sensitivity of 115.78 kPa−1). And the sensitivity and range of the sensor can be adjusted by the force-sensitive layer orientation design. Additionally, the sensor's response time is less than 30 ms, the recovery time is about 30 ms. The field-effect pressure sensor could detect ultra-low pressure (about 1.3 mg) of the chrysanthemum petals, and also could record the dynamic crawling process of the insect. [Display omitted] [ABSTRACT FROM AUTHOR]

Featured Application: The precise relationship between material thickness and material properties will guide the application of layered black phosphorus materials. As a two-dimensional (2D) semiconductor material with excellent optoelectronic properties, black phosphorus (BP) has attracted widespread attention. It was found that the energy band structure of BP crystal changes with its thickness if BP is thin. To explore the accurate effects of the BP thicknesses on devices, BP-FETs with different BP thickness (50 nm, 40 nm, 30 nm, 20 nm, and 6 nm) as the channel material were fabricated by mechanical exfoliation technique. The output characteristics and transfer characteristics of the BP-FETs were analyzed in detail. The source–drain current (Ids) of devices is directly related to the BP thickness. The larger the BP thickness, the larger the Ids obtained under the same gate voltage modulation, but the electric field modulation effect decreases. Especially, the correlation between Ids and BP thickness can be described by a semi-empirical formula, which predicts that only when the BP thickness is less than 21.7 nm, the band structure of BP will be significantly affected by the thickness. The mobility of the carrier increases with the increasing of the BP thickness; for BP thickness of 6 nm, 20 nm, 30 nm, 40 nm, and 50 nm, the mobility is about 52.5 cm2/Vs, 187.5 cm2/Vs, 214.4 cm2/Vs, 252.5 cm2/Vs, and 336.4 cm2/Vs. Finally, the 50 nm BP in FET was etched to 30 nm using plasma etching technology to further verify the above experimental results. It also confirmed that plasma etching methods tend to introduce structural damage and impurity elements, which in turn has an impact on the output characteristics of the device. [ABSTRACT FROM AUTHOR]

Two-dimensional materials-based field-effect transistors (FETs) are promising biosensors because of their outstanding electrical properties, tunable band gap, high specific surface area, label-free detection, and potential miniaturization for portable diagnostic products. However, it is crucial for FET biosensors to have a high electrical performance and stability degradation in liquid environments for their practical application. Here, a high-performance InSe-FET biosensor is developed and demonstrated for the detection of the CA125 biomarker in clinical samples. The InSe-FET is integrated with a homemade microfluidic channel, exhibiting good electrical stability during the liquid channel process because of the passivation effect on the InSe channel. The InSe-FET biosensor is capable of the quantitative detection of the CA125 biomarker in breast cancer in the range of 0.01–1000 U/mL, with a detection time of 20 min. This work provides a universal detection tool for protein biomarker sensing. The detection results of the clinical samples demonstrate its promising application in early screenings of major diseases. [ABSTRACT FROM AUTHOR]

In this study, reduced graphene oxide (rGO) - porous silicon (PS) hybrid structures are suggested to create a field-effect transistor (FET). The electrical properties and switching characteristics of the obtained rGO - PS-based FET were studied in both DC and AC modes. A significant influence of the supporting PS layer on the transport of charge carriers in the graphene film was established. A decrease in resistance and an increase in the capacity of the graphene FET channel due to photogenerated charge carriers in the porous layer were found. Based on the impedance spectra, the parameters of the equivalent circuit model of the rGO - PS-based FET for different gate voltages are determined. [ABSTRACT FROM AUTHOR]

The past several decades have witnessed great progress in high‐performance field effect transistors (FET) as one of the most important electronic components. At the same time, due to their intrinsic advantages, such as multiparameter accessibility, excellent electric signal amplification function, and ease of large‐scale manufacturing, FET as tactile sensors for flexible wearable devices, artificial intelligence, Internet of Things, and other fields to perceive external stimuli has also attracted great attention and become a significant field of general concern. More importantly, FET has a unique three‐terminal structure, which enables its different components to detect external mechanics through different sensing mechanisms. On one hand, it provides an important platform to shed deep insights into the underlying mechanisms of the tactile sensors. On the other hand, these properties could in turn endow excellent components for the construction of tactile matrix sensor arrays with high quality. With special emphasis on the configuration of FETs, this review classified and summarized structure‐optimized FET tactile sensors with gate, dielectric layer, semiconductor layer, and source/drain electrodes as sensing active components, respectively. The working principles and the state‐of‐the‐art protocols in terms of high‐performance tactile sensors are detail discussed and highlighted, the innovative pixel distribution and integration analysis of the transistor sensor matrix array concerning flexible electronics are also introduced. We hope that the introduction of this review can provide some inspiration for future researchers to design and fabricate high‐performance FET‐based tactile sensor chips for flexible electronics and other fields. [ABSTRACT FROM AUTHOR]