Search

The charge neutrality point (CNP) is one of the essential parameters in the development of graphene field-effect transistors (GFETs). For GFET with an intrinsic graphene channel layer, the CNP is typically near-zero-volt gate voltage, implying that a well-balanced density of electrons and holes exists in the graphene channel layer. Fabricated GFET, however, typically exhibits CNP that is either positively or negatively shifted from the near-zero-volt gate voltage, implying that the graphene channel layer is unintentionally doped, leading to a unipolar GFET transfer characteristic. Furthermore, the CNP is also modulated in time, indicating that charges are dynamically induced in the graphene channel layer. In this work, understanding and mitigating the CNP shift were attempted by introducing passivation layers made of polyvinyl alcohol and polydimethylsiloxane onto the graphene channel layer. The CNP was found to be negatively shifted, recovered back to near-zero-volt gate voltage, and then positively shifted in time. By analyzing the charge density, carrier mobility, and correlation between the CNP and the charge density, it can be concluded that positive CNP shifts can be attributed to the charge trapping at the graphene/SiO2 interface. The negative CNP shift, on the other hand, is caused by dipole coupling between dipoles in the polymer layer and carriers on the surface of the graphene layer. By gaining a deeper understanding of the intricate mechanisms governing the CNP shifts, an ambiently stable GFET suitable for next-generation electronics could be realized. [ABSTRACT FROM AUTHOR]

Copyright of Rare Metals is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In this paper, we analyze the modulation characteristics and the ultimate modulation frequency of the terahertz (THz) hot-electron FET bolometers with the graphene channels (GCs), metal gate (MG), and gate barrier layers (BLs) in a wide temperature range. Our results predict that the responsivity of GC-FET bolometers decreases with decreasing operating temperature. This is attributed to a dramatic drop in the thermionic GC-MG current (characterized by the relatively large activation energy) and its modulated component when the temperature lowers. A further decrease in the temperature results in a fairly strong responsivity roll-off. In contrast, the responsivity of the GC-FET detectors with the temperature-adjusted load resistance rises with decreasing temperature because the temperature lowering leads to an increase in the electron energy relaxation time and promotes more effective heating by the impinging THz radiation. In this case, the weakening of the thermionic current is compensated by the commensurate increase in the load resistance. [ABSTRACT FROM AUTHOR]

In this paper, we propose and analyze the terahertz (THz) bolometric vector detectors based on the graphene-channel field-effect transistors (GC-FET) with the black-P gate barrier layer or with the composite b-BN/black-P/b-BN gate layer. The phase difference between the signal received by the FET source and drain substantially affects the plasmonic resonances. This results in a resonant variation of the detector response on the incoming THz signal phase shift and the THz radiation angle of incidence. [ABSTRACT FROM AUTHOR]

Two-dimensional (2D) transition metal dichalcogenides (TMDs) are excellent candidates for electronic applications because of their high carrier mobility, tunable bandgap energy depending on the number of layers, monolayer thickness, and the absence of dangling bonds on their surfaces. Despite these advantages, the crystalline structures of TMDs contain intrinsic defects such as vacancies, adatoms, grain boundaries, and substitutional impurities, which can cause large contact resistance at the source/drain interface. Customized engineering of interfaces and defects, which provides a method to modulate the properties of TMDs, is crucial as it can significantly enhance device performance. Herein, we explored a novel electrode to enhance the interface between electrode and semiconductor materials. we report the synthesis of high-quality atomically thin MoO2 using atmospheric pressure chemical vapor deposition (APCVD) and its application to field-effect transistors. To improve crystallinity of MoO2, we investigated the influence of hydrogen concentration, a key parameter in the reduction process, on the synthesis of high-crystallinity MoO₂. By adding NaCl to MoO₃ powder, we optimized the synthesis of high-crystallinity MoO₂. Utilizing the optimized MoO₂, we fabricated transistors that exhibited a mobility of 29.1 cm²/V∙s and an on/off ratio of 1.78 × 10⁴, demonstrating excellent performance. Our findings confirm that single-crystal MoO2 can be effectively applied as a contact electrode in high-performance two-dimensional semiconductor devices. [ABSTRACT FROM AUTHOR]

Liquid metal (LM) electronic ink (e‐ink) is a promising new‐generation material for printed electronics. Extended from this ideal platform, such ink can be post‐processed or loaded with semiconductor nanoparticles to further make semiconductors in the forms of dots, wires, and films on its surface. In this way, targeted semiconductors can be quickly fabricated and patterned as desired with low cost at around room temperature. This leads to the unconventional bottom‐up strategy for direct manufacture of functional devices. Along this direction, a series of p–n junction diodes, field‐effect transistors, and light‐emitting devices have been developed. LM‐printed semiconductor would significantly innovate the classical processes of preparing integrated circuits and electronic devices. To push forward further progress of this cutting‐edge frontier, this article is dedicated to present an overview of LM‐printed semiconductor. The material category of LM semiconductor e‐inks and their synthesis approaches is introduced. Then the core strategies toward printing semiconductors are systematically outlined. Following that, the typical printed semiconductor materials and electronic devices thus constructed as well as their potential applications are summarized. Finally, scientific and technical challenges thus raised are interpreted. Perspective in the area is given. [ABSTRACT FROM AUTHOR]

Recently, field‐effect transistors (FETs) have emerged as a novel type of multiparameter, high‐performance, highly integrated platform for biochemical detection, leveraging their classical three‐terminal structure, working principles, and fabrication methods. Notably, graphene materials, known for their exceptional electrical and optical properties as well as biocompatibility, serve as a fundamental component of these devices, further enhancing their advantages in biological detection. This review places special emphasis on recent advancements in graphene field‐effect transistor (GFET)‐based biosensors and focuses on four main areas: i) the basic concepts of FETs and the specific electrical properties of GFETs; ii) various state‐of‐the‐art approaches to enhance the performance of GFET‐based biosensors in terms of operating principles and the "3S"—stability, sensitivity, and specificity; iii) multiplexed detection strategies for GFET‐based biosensors; and iv) the current challenges and future perspectives in the field of GFET‐based biosensors. It is hoped that this article can profoundly elucidate the development of GFET biosensors and inspire a broader audience. [ABSTRACT FROM AUTHOR]

In food safety analysis, the detection and control of foodborne pathogens and their toxins are of great importance. Monitoring of virus transmission is equally important, especially in light of recent findings that coronaviruses have been detected in frozen foods and packages during the current global epidemic of coronavirus disease 2019. In recent years, field-effect transistor (FET) biosensors have attracted considerable scholarly attention for pathogenic microorganisms and toxins detection and sensing due to their rapid response time, high sensitivity, wide dynamic range, high specificity, label-free detection, portability, and cost-effectiveness. FET-based biosensors can be modified with specific recognition elements, thus providing real-time qualitative and semiquantitative analysis. Furthermore, with advances in nanotechnology and device design, various high-performance nanomaterials are gradually applied in the detection of FET-based biosensors. In this article, we review specific detection in different biological recognition elements are immobilized on FET biosensors for the detection of pathogenic microorganisms and toxins, and we also discuss nonspecific detection by FET biosensors. In addition, there are still unresolved challenges in the development and application of FET biosensors for achieving efficient, multiplexed, in situ detection of pathogenic microorganisms and toxins. Therefore, directions for future FET biosensor research and applications are discussed. [ABSTRACT FROM AUTHOR]

Highlights: The review provides a brief overview of the basic structure, operating mechanism, and key performance indicators of flexible graphene field-effect transistors. The review details the preparation strategy of flexible graphene field-effect transistors focusing on material selection and patterning techniques. The review analyzes the latest strategies for developing wearable and implantable flexible biomedical sensors based on flexible graphene field-effect transistors. Flexible electronics are transforming our lives by making daily activities more convenient. Central to this innovation are field-effect transistors (FETs), valued for their efficient signal processing, nanoscale fabrication, low-power consumption, fast response times, and versatility. Graphene, known for its exceptional mechanical properties, high electron mobility, and biocompatibility, is an ideal material for FET channels and sensors. The combination of graphene and FETs has given rise to flexible graphene field-effect transistors (FGFETs), driving significant advances in flexible electronics and sparked a strong interest in flexible biomedical sensors. Here, we first provide a brief overview of the basic structure, operating mechanism, and evaluation parameters of FGFETs, and delve into their material selection and patterning techniques. The ability of FGFETs to sense strains and biomolecular charges opens up diverse application possibilities. We specifically analyze the latest strategies for integrating FGFETs into wearable and implantable flexible biomedical sensors, focusing on the key aspects of constructing high-quality flexible biomedical sensors. Finally, we discuss the current challenges and prospects of FGFETs and their applications in biomedical sensors. This review will provide valuable insights and inspiration for ongoing research to improve the quality of FGFETs and broaden their application prospects in flexible biomedical sensing. [ABSTRACT FROM AUTHOR]

Precise control over polarity in field‐effect transistors (FETs) plays a pivotal role in the design and construction of complementary metal–oxide–semiconductor (CMOS) logic circuits. In particular, achieving such precise polarity control in 2D semiconductors is crucial for the further development of advanced electronic applications beyond unit devices. This paper presents a systematic investigation on the reversible transition of carrier types in a 2D MoTe2 semiconductor under different annealing atmospheres. Photoemission spectroscopy and density functional theory (DFT) calculations demonstrate that annealing processes in vacuum and in ambient air induce a modification in the density of states, resulting in alterations in p‐type or n‐type characteristics. These reversible changes are attributed to the physisorption and elimination of oxygen on the surface of MoTe2. Furthermore, it is found that the device geometry affects the polarity of the transistor. By strategically manipulating both the annealing conditions and the geometric configuration, the n‐ and p‐type unipolar characteristics of MoTe2 FETs are successfully modulated and ultimately demonstrating that the functionality of not only a complementary inverter with a high voltage gain of ≈20, but also more complex logic circuits of NAND and NOR gates. [ABSTRACT FROM AUTHOR]

The ionizing radiation low-cost and portable sensors based on nanostructured materials are in demand in many fields such as safety, medicine, space, and scientific research. Graphene field-effect transistors (FETs) have high potential for radiation detection. In this study, the graphene FETs were created by depositing a film-forming suspension of reduced graphene oxide (rGO) nanoparticles on the sili- con substrate with a SiO2 or thermally oxidized porous silicon (por-Si) layer and air-drying at room temperature. The electrical characteristics of the rGO-based FETs were studied in DC and AC modes. The dependencies of the drain current on the gate voltage have linear sections, the position of which depends on the sign of the drain-source voltage. It was found that the position of the Dirac point in the FETs based on the rGO-SiO2-Si and rGO-por-Si-Si structures was near the 0.8 V gate voltage. The possibility of using the obtained FETs as ionizing radiation detectors was investigated. A linear increase in the internal resistance of the rGO film in AC mode was established with increasing duration of irradiation with ẞ-particles and y-quanta formed as a result of the decay of the 226 Ra radium isotope. The radiation detector based on the rGO-por-Si-Si structure is characterized by a higher sensitivity to ionizing radiation, which is probably due to the greater thickness of the por-Si compared to the SiO2 layer. The radiation-induced change in electrical resistance of the studied FETs was greater in the low- frequency range. We explored possible mechanisms of the ionizing radiation influence on the rGO-based FETs conductivity. [ABSTRACT FROM AUTHOR]

The recent emergence of Janus 2D materials like SnSSe, derived from SnS2, reveals unique electrical and optical features, such as asymmetrical electronic structure, enhanced carrier mobility, and tunable bandgap. Previous theoretical studies have discuss the electronic properties of Janus SnSSe, but experimental evidence is limited. This study presents a two‐step method for synthesizing Janus SnSSe, involving hydrogen plasma treatment and in situ selenization. Optimized conditions (38 W, 1.5 min, 250 °C) are determined using Raman spectroscopy and AFM analysis. XPS confirmed SnSSe's elemental composition, while KPFM reveals a significant reduction in the work function (from 5.26 down to 5.14 eV) for the first time, indicating asymmetrically induced n‐type doping. Finally, field‐effect transistors (FETs) derived from SnSSe exhibited significantly enhanced mobility and on‐current, as well as n‐type doping, compared to SnS2‐based FETs. These findings lay a crucial foundation for developing high‐performance 2D electronic and optoelectronic devices. [ABSTRACT FROM AUTHOR]

Excellent stability, low cost, high response, and sensitivity of indium oxide (In2O3), a metal oxide semiconductor, have been verified in the field of gas sensing. Conventional In2O3 gas sensors employ simple and easy–to–manufacture resistive components as transducers. However, the swift advancement of the Internet of Things has raised higher requirements for gas sensors based on metal oxides, primarily including lowering operating temperatures, improving selectivity, and realizing integrability. In response to these three main concerns, field–effect transistor (FET) gas sensors have garnered growing interest over the past decade. When compared with other metal oxide semiconductors, In2O3 exhibits greater carrier concentration and mobility. The property is advantageous for manufacturing FETs with exceptional electrical performance, provided that the off–state current is controlled at a sufficiently low level. This review presents the significant progress made in In2O3 FET gas sensors during the last ten years, covering typical device designs, gas sensing performance indicators, optimization techniques, and strategies for the future development based on In2O3 FET gas sensors. [ABSTRACT FROM AUTHOR]

Quantum point contacts with a short (100-nm) channel in a high-mobility two-dimensional electron gas of GaAs/Al(Ga)As heterostructures and a short-channel p-type field-effect transistor in a silicon-on-insulator structure were fabricated and studied experimentally and by modeling at the Rzhanov Institute of Semiconductor Physics, Siberian Branch, Russian Academy of Sciences, Novosibirsk, Russia, in order to study the response of the samples to weak irradiation by an electromagnetic field with a frequency of ~2 GHz. This response in the tunneling mode at a temperature of 4.2 K turned out to be giant and was observed against the background of features caused by impurity disorder. [ABSTRACT FROM AUTHOR]

In this work, the Landauer approach-based short channel model of a graphene field effect transistor has been presented. The quasi-ballistic and ballistic transport mechanism is explained by this approach for nanoscale transistors. The concept of the virtual source is considered to obtain the carrier density in active regions. Here, we apply the Landauer approach for short-channel graphene field effect transistors relating to the parameter in the virtual source model. The mobility of the model has been improved including various scattering effects like impurity scattering, acoustic phonon scattering, and optical phonon scattering. The dynamic resistance model is considered due to asymmetry transport in the electron branch and hole branch. The proposed model has been verified with several experimental works for model validation. The comparisons of the model simulation with several experimental results that have been reported in the literature match well for different short channel lengths of graphene. [ABSTRACT FROM AUTHOR]

The field-effect transistors (FETs) based on reduced graphene oxide (rGO) with SiO2, porous silicon (PS), and oxidized porous silicon (PSox) supporting layers were obtained. The influence of charged impurities in the silicon substrate and electrically active defects in the support layers on the electrical properties of the FETs was studied based on the capacitance-voltage characteristic analysis. Localized electron states in the SiO2, PS, and PSox supporting layers that affect the charge transfer in the rGO-based FETs were determined using thermally stimulated depolarization spectroscopy. The influence mechanisms of various supporting layers on the electrical characteristics of the obtained FETs are discussed. [ABSTRACT FROM AUTHOR]

Since two‐dimensionalal (2D) materials have distinct chemical and physical properties, they are widely used in various sectors of modern technologies. In the domain of diagnostic biodevices, particularly for point‐of‐care (PoC) biomedical diagnostics, 2D‐based field‐effect transistor biosensors (bio‐FETs) demonstrate substantial potential. Here, in this review article, the operational mechanisms and detection capabilities of biosensing devices utilizing graphene, transition metal dichalcogenides (TMDCs), black phosphorus, and other 2D materials are addressed in detail. The incorporation of these materials into FET‐based biosensors offers significant advantages, including low detection limits (LOD), real‐time monitoring, label‐free diagnosis, and exceptional selectivity. The review also highlights the diverse applications of these biosensors, ranging from conventional to wearable devices, underscoring the versatility of 2D material‐based FET devices. Additionally, the review provides a comprehensive assessment of the limitations and challenges faced by these devices, along with insights into future prospects and advancements. Notably, a detailed comparison of FET‐based biosensors is tabulated along with various other biosensing platforms and their working mechanisms. Ultimately, this review aims to stimulate further research and innovation in this field while educating the scientific community about the latest advancements in 2D materials‐based biosensors. [ABSTRACT FROM AUTHOR]

Effective Ohmic contact between metals and their conductive channels is a crucial step in developing high-performance Ga2O3-based transistors. Distinct from bulk materials, excess thermal energy of the annealing process can destroy the low-dimensional material itself. Given the thermal budget concern, a feasible and moderate solution (i.e., Ar-containing plasma treatment) is proposed to achieve effective Ohmic junctions with (100) β-Ga2O3 nanosheets. The impact of four kinds of plasma treatments (i.e., gas mixtures SF6/Ar, SF6/O2/Ar, SF6/O2, and Ar) on (100) β-Ga2O3 crystals is comparatively studied by X-ray photoemission spectroscopy for the first time. With the optimal plasma pre-treatment (i.e., Ar plasma, 100 W, 60 s), the resulting β-Ga2O3 nanosheet field-effect transistors (FETs) show effective Ohmic contact (i.e., contact resistance RC of 104 Ω·mm) without any post-annealing, which leads to competitive device performance such as a high current on/off ratio (>107), a low subthreshold swing (SS, 249 mV/dec), and acceptable field-effect mobility ( μ e f f , ~21.73 cm2 V−1 s−1). By using heavily doped β-Ga2O3 crystals (Ne, ~1020 cm−3) for Ar plasma treatments, the contact resistance RC can be further decreased to 5.2 Ω·mm. This work opens up new opportunities to enhance the Ohmic contact performance of low-dimensional Ga2O3-based transistors and can further benefit other oxide-based nanodevices. [ABSTRACT FROM AUTHOR]

The impact of radiation on MoS2-based devices is an important factor in the utilization of two-dimensional semiconductor-based technology in radiation-sensitive environments. In this study, the effects of gamma irradiation on the electrical variations in MoS2 field-effect transistors with buried local back-gate structures were investigated, and their related effects on Al2O3 gate dielectrics and MoS2/Al2O3 interfaces were also analyzed. The transfer and output characteristics were analyzed before and after irradiation. The current levels decreased by 15.7% under an exposure of 3 kGy. Additionally, positive shifts in the threshold voltages of 0.50, 0.99, and 1.15 V were observed under irradiations of 1, 2, and 3 kGy, respectively, compared to the non-irradiated devices. This behavior is attributable to the comprehensive effects of hole accumulation in the Al2O3 dielectric interface near the MoS2 side and the formation of electron trapping sites at the interface, which increased the electron tunneling at the MoS2 channel/dielectric interface. [ABSTRACT FROM AUTHOR]

Amorphous IGZO (a‐IGZO) thin‐film transistors (TFTs) are standard backplane electronics to power active‐matrix organic light‐emitting diode (AMOLED) televisions due to their high carrier mobility and negligible low leakage characteristics. Despite their advantages, limitations in color depth arise from a steep subthreshold swing (SS) (≤ 0.1 V/decade), necessitating costly external compensation for IGZO transistors. For mid‐size mobile applications such as OLED tablets and notebooks, it is important to ensure controllable SS value (≥ 0.3 V/decade). In this study, a conversion mechanism during plasma‐enhanced atomic layer deposition (PEALD) is proposed as a feasible route to control the SS. When a pulse of a diethylzinc (DEZn) precursor is exposed to the M2O3 (M = In or Ga) surface layer, partial conversion of the underlying M2O3 to ZnO is predicted on the basis of density function theory calculations. Notably, significant distinctions between In‐Ga‐Zn (Case I) and In‐Zn‐Ga (Case II) films are observed: Case II exhibits a lower growth rate and larger Ga/In ratio. Case II TFTs with a‐IGZO (subcycle ratio of In:Ga:Zn = 3:1:1) show reasonable SS values (313 mV decade−1) and high mobility (µFE) of 29.3 cm2 Vs−1 (Case I: 84 mV decade−1 and 33.4 cm2 Vs−1). The rationale for Case II's reasonable SS values is discussed, attributing it to the plausible formation of In‐Zn defects, supported by technology computer‐aided design (TCAD) simulations. [ABSTRACT FROM AUTHOR]

An affinity nanobiosensor is presented that uses an aptamer-functionalized Ni3(HITP)2 metal-organic framework (MOF). The device is a field-effect transistor (FET) with the MOF as the conducting channel and is functionalized with an aptamer for specific biomarker recognition. Binding between the aptamer and the target biomarker induces a change in the carrier density in the MOF, resulting in measurable changes in FET characteristics for determination of the biomarker concentration. In situ synthesis of the MOF enhances the adhesion between the MOF film and electrodes to reduce noise during sensor operations while also allowing devices to be potentially mass-producible at a reduced cost. Thanks to the porous structure of the MOF, the aptamer surface density on the MOF is optimized to enhance sensitivity for biomarker measurements. Experimental results show that the MOF nanobiosensor is capable of reliable and sensitive measurements of tumor necrosis factor α (TNF-α) with a responsivity of 0.38 mV/pM and a limit of detection of 8.7 pM, which are 2.7 times the responsivity and 34% of the limit of detection of a comparison aptameric sensor that used manually transferred graphene as a transduction material. [ABSTRACT FROM AUTHOR]

Carbon monoxide (CO) poses significant health risks to humans, impacts the lifespan and efficiency of hydrogen fuel cells as a primary impurity, and is also used for early insulation fault diagnosis in equipment. However, portable CO detectors with low detection limits are still lacking. In this work, we demonstrate a floating-gate field-effect transistor (FG-FET) for a CO gas sensor, in which the carbon nanotubes (CNTs) and tin oxide (SnO2) film are separated by Y2O3 layer and act as channel and sensing layer, respectively. Thanks to the wettability of Y2O3 and the secondary annealing process in the preparation of SnO2 by sol-gel method, the structure not only ensures the stability of the channel but also possesses an optimized interface state with sensing material, protecting the stability of the device and facilitating excellent transmission of the sensing signal. The SnO2/CNT FG-FET sensor achieved effective monitoring of 1 ppb of CO at 150°C, breaking the current CO detection limit. Furthermore, the sensor demonstrates good regular response in the range of 1-30 ppb CO gas concentration. The prepared CO sensor features an extremely low detection limit, ultrahigh sensitivity, and excellent selectivity, providing an idea for high-performance FET gas sensor development. [ABSTRACT FROM AUTHOR]

Semi‐floating gate field‐effect transistors (SFG‐FETs) based on 2D materials have received much attention due to their unique optoelectronic characteristics, potential applications in near‐memory computing and constructing sensing‐memory‐processing units. Here, the non‐volatile and gate‐controlled multistate photovoltaic response of a WSe2/h‐BN/graphene SFG‐FET is investigated both in experimental and theoretical aspects. Due to the ambipolar carrier transport of WSe2 channel, both electrons and holes can be stored in the graphene floating gate layer, which results in two evident memory windows on the round sweep transfer characteristic curve. Different charge‐stored states of the SFG layer enable the channel to form a lateral junction that can be adjusted by the gate voltage, which leads to the gate‐controlled multistate photovoltaic response. A theoretical model is implemented to explain the memory and the multistate photovoltaic response behaviors in a quasi‐quantitative level. The relationship between the charge‐stored states in the SFG and the photo‐response, as well as its dependence on the gate voltage are systematically analyzed. These research results provide a reliable way for realizing high‐performance multi‐functional photodetectors based on SFG‐FETs and for thorough understanding the complicated optoelectronic behaviors of SFG‐FETs. [ABSTRACT FROM AUTHOR]

Numerous efforts have been undertaken to mitigate the Debye screening effect of FET biosensors for achieving higher sensitivity. There are few reports that show sub-femtomolar detection of biomolecules by FET mechanisms but they either suffer from significant background noise or lack robust control. In this aspect, deformed/crumpled graphene has been recently deployed by other researchers for various biomolecule detection like DNA, COVID-19 spike proteins and immunity markers like IL-6 at sub-femtomolar levels. However, the chemical vapor deposition (CVD) approach for graphene fabrication suffers from various surface contamination while the transfer process induces structural defects. In this paper, an alternative fabrication methodology has been proposed where glass substrate has been initially texturized by wet chemical etching through the sacrificial layer of synthesized silver nanoparticles, obtained by annealing of thin silver films leading to solid state dewetting. Graphene has been subsequently deposited by thermal reduction technique from graphene oxide solution. The resulting deformed graphene structure exhibits higher sensor response towards glial fibrillary acidic protein (GFAP) detection with respect to flat graphene owing to the combined effect of reduced Debye screening and higher surface area for receptor immobilization. Additionally, another interesting aspect of the reported work lies in the biomolecule capture by dielectrophoretic (DEP) transport on the crests of the convex surfaces of graphene in a coplanar gated topology structure which has resulted in 10 aM and 28 aM detection limits of GFAP in buffer and undiluted plasma respectively, within 15 min of application of analyte. The detection limit in buffer is almost four decades lower than that documented for GFAP using biosensors which is is expected to pave way for advancing graphene FET based sensors towards ultrasensitive point-of-care diagnosis of GFAP, a biomarker for traumatic brain injury. [ABSTRACT FROM AUTHOR]

A novel highly π-extended heteroarene Benzo[1,2-b:4,5-b']di(naphtho[1,2-d]thiophene) (DBTBT) was used for organic field-effect transistors (OFETs). The mobilities of OFET were greatly improved from 0.34–0.58 cm2V−1s−1 to 1.02–1.75 cm2V−1s−1 by morphology tuning through 2 steps' controlling substrate temperature. More importantly, the OFETs showed a good ambient stability in 30 days measurements. The flexible OFET arrays were prepared on polyethylene terephthalate substrate with octadecyl trichlorosilane modified polymethylsilsesquioxane/polyacrylonitrile gate dielectrics and demonstrated a 100% yield. Further, this flexible cell was used for ultraviolet light detection, which showed good ability of detecting low power light (such as λ = 254 nm, 7 μW/cm2). [ABSTRACT FROM AUTHOR]

Field-effect transistor (FET)-based biosensors exhibit excellent performance characteristics such as small size, ease of mass production, high versatility, and comparably low cost. In recent years, numerous FET biosensors based on various nanomaterials including silicon nanowires, carbon nanotubes, graphene, and transition metal dichalcogenides have been developed to detect a wide range of biomarkers that play a crucial role in early disease diagnosis, therapeutic monitoring and prognostic assessment. This review provides an overview of the structure, working principle, functionalization strategies and detection factors associated with FET biosensors based on diverse nanomaterials. Additionally, this paper discusses the applications of these diagnostic devices for detecting clinically relevant biomarkers such as nucleic acids, metabolites, proteins, cancer biomarkers, and hormones among others. The concluding section provides a comprehensive overview of the numerous challenges encountered in the widespread implementation of nanomaterial-based FET biosensors for clinical detection, while also presenting the future prospects for these biosensors based on current research advancements. Field-effect transistor (FET)-based biosensors exhibit excellent performance characteristics such as small size, ease of mass production, high versatility, and comparably low cost. In recent years, numerous FET biosensors based on various nanomaterials have been developed to detect a wide range of biomarkers that play a crucial role in early disease diagnosis, therapeutic monitoring and prognostic assessment. This review provides an overview of the structure, working principle, functionalization strategies and detection factors associated with field-effect transistor biosensors based on diverse nanomaterials. Additionally, this article discusses the applications of these diagnostic devices for detecting clinically relevant biomarkers such as nucleic acids, metabolites, proteins, cancer biomarkers, hormones among others. [ABSTRACT FROM AUTHOR]

The remarkable successes of graphene have sparked increasing interest in elemental two‐dimensional (2D) materials, also referred to as Xenes. Due to their chemical simplicity and appealing physiochemical properties, Xenes have shown particular potential for numerous (opto) electronic, iontronic, and energy applications. Among them, layered α‐phase tellurene has demonstrated the most promise, thanks to the recent successes in the chemical synthesis of highly crystalline 2D tellurene. However, the general electronic and electrochemical properties of tellurene in electrolyte systems remain ambiguous, hindering their further development. In this work, we studied the electrostatic gating, electrocatalysis, and electrochemical stability of tellurene in electrolyte systems. Our results show that tellurene obtained from both hydrothermal and chemical vapor deposition methods, two mainstream synthetic approaches for Xenes, demonstrates thickness‐dependent ambipolar transport with high hole mobility and stability in both aqueous electrolytes and ionic liquids. More importantly, the electrochemical properties of tellurene are investigated via the emerging on‐chip electrochemistry. Pristine tellurene demonstrates hydrogen evolution reaction with low Tafel slopes and remarkable electrochemical stability in acidic electrolytes over a large potential window. Our study provides a comprehensive understanding of the iontronic and electrochemical properties of tellurene, paving the way for the broad adoption of Xenes in sensors, synaptic devices, and electrocatalysis. [ABSTRACT FROM AUTHOR]

The rapid development in information technologies necessitates rapid advancements of their supporting hardware. In particular, new computing paradigms are needed to overcome the bottleneck of traditional von Neumann architecture. Bottom‐up innovation, especially at the materials and devices level, has the potential to disrupt existing technologies through their emergent phenomena. As a new type of conceptual device, 2D ferroelectric field‐effect transistor (FeFET) is highly sought after due to its potential integration with modern semiconductor processes. Its low power consumption, area efficiency, and ultra‐fast operation provide an extra edge over traditional technologies. This review highlights recent developments in 2D FeFET, covering their device construction, working mechanisms, 2D ferroelectric polarization mechanism, multi‐functional applications and prospects. In particular, the combination of 2D semiconductor and ferroelectric dielectric materials for multi‐functionality applications is discussed. This includes non‐volatile memories (NVM), neural network computing, non‐volatile logic operation, and photodetectors. As a novel device platform, 2D semiconductor and ferroelectric interfaces are bestowed with a plethora of emergent physical mechanisms and applications. [ABSTRACT FROM AUTHOR]

Graphene with an atomically thin structure is considered to be a highly sensitive transducer capable of converting diverse external stimuli into measurable electrical signals. The generated signals, such as current and resistance, can be extracted through electrical contact to graphene. Conventional methods for contact formation are usually based on physical deposition of conductive materials on the target graphene. Here, we propose a method for in situ chemical synthesis of electrical contacts to graphene as an alternative approach that complements conventional physical methods. CO2 laser irradiation on a polyimide film with monolayer graphene on top can convert the polyimide surface to conductive electrodes of laser-induced graphene (LIG) that electrically connect to the existing graphene channel. Laser-scribing conditions, such as the power and scan rate, can modulate the contact resistance of the LIG–graphene junction. Various arbitrary shapes of in situ LIG contacts can be scribed to the direct writing ability of the laser. The proposed in situ LIG contact method can be extended to other carbon nanomaterials, such as carbon nanotubes and PEDOT:PSS. As a proof of concept of the in situ LIG contacts to graphene for electronic device applications, graphene field-effect transistors were demonstrated on a graphene-supported polyimide substrate with LIG–graphene junctions as source/drain electrodes. Our approach will pave the way for the simple and low-cost fabrication of versatile graphene electronic devices by utilizing the existing LIG technology specialized for energy devices and sensors. [ABSTRACT FROM AUTHOR]

FET-based charge carrier mobility measurements in low-conductivity materials, as well as semiconductor materials with a high density of trapping states, such as nanocrystals and polycrystalline films, are highly distorted due to charge accumulation in the transistor structure. In this work, a comparative study of the measurement of the mobility of charge carrier in conductive polymers, nanocrystals and polycrystalline films, using the analysis of output and transfer characteristics, was carried out. It is shown that using output characteristics instead of transfer characteristics for calculating the charge carrier mobility helps to avoid a systematic error in the measurement. [ABSTRACT FROM AUTHOR]

Graphene-based materials are actively being investigated as sensing elements for the detection of different analytes. Both graphene grown by chemical vapor deposition (CVD) and graphene oxide (GO) produced by the modified Hummers' method are actively used in the development of biosensors. The production costs of CVD graphene- and GO-based sensors are similar; however, the question remains regarding the most efficient graphene-based material for the construction of point-of-care diagnostic devices. To this end, in this work, we compare CVD graphene aptasensors with the aptasensors based on reduced GO (rGO) for their capabilities in the detection of NT-proBNP, which serves as the gold standard biomarker for heart failure. Both types of aptasensors were developed using commercial gold interdigitated electrodes (IDEs) with either CVD graphene or GO formed on top as a channel of liquid-gated field-effect transistor (FET), yielding GFET and rGO-FET sensors, respectively. The functional properties of the two types of aptasensors were compared. Both demonstrate good dynamic range from 10 fg/mL to 100 pg/mL. The limit of detection for NT-proBNP in artificial saliva was 100 fg/mL and 1 pg/mL for rGO-FET- and GFET-based aptasensors, respectively. While CVD GFET demonstrates less variations in parameters, higher sensitivity was demonstrated by the rGO-FET due to its higher roughness and larger bandgap. The demonstrated low cost and scalability of technology for both types of graphene-based aptasensors may be applicable for the development of different graphene-based biosensors for rapid, stable, on-site, and highly sensitive detection of diverse biochemical markers. [ABSTRACT FROM AUTHOR]

In this study, the development and characterization of 2D ferroelectric field‐effect transistor (2D FeFET) devices are presented, utilizing nanoscale ferroelectric HfZrO2 (HZO) and 2D semiconductors. The fabricated device demonstrated multi‐level data storage capabilities. It successfully emulated essential biological characteristics, including excitatory/inhibitory postsynaptic currents (EPSC/IPSC), Pair‐Pulse Facilitation (PPF), and Spike‐Timing Dependent Plasticity (STDP). Extensive endurance tests ensured robust stability (107 switching cycles, 105 s (extrapolated to 10 years)), excellent linearity, and high Gmax/Gmin ratio (>105), all of which are essential for realizing multi‐level data states (>7‐bit operation). Beyond mimicking synaptic functionalities, the device achieved a pattern recognition accuracy of ≈94% on the Modified National Institute of Standards and Technology (MNIST) handwritten dataset when incorporated into a neural network, demonstrating its potential as an effective component in neuromorphic systems. The successful implementation of the 2D FeFET device paves the way for the development of high‐efficiency, ultralow‐power neuromorphic hardware which is in sub‐femtojoule (48 aJ/spike) and fast response (1 µs), which is 104 folds faster than human synapse (≈10 ms). The results of the research underline the potential of nanoscale ferroelectric and 2D materials in building the next generation of artificial intelligence technologies. [ABSTRACT FROM AUTHOR]

Two-dimensional (2D) materials hold great promise for future applications, notably their use as biosensing channels in the field-effect transistor (FET) configuration. On the road to implementing one of the most widely used 2D materials, graphene, in FETs for biosensing, key issues such as operation conditions, sensitivity, selectivity, reportability, and economic viability have to be considered and addressed correctly. As the detection of bioreceptor-analyte binding events using a graphene-based FET (gFET) biosensor transducer is due to either graphene doping and/or electrostatic gating effects with resulting modulation of the electrical transistor characteristics, the gFET configuration as well as the surface ligands to be used have an important influence on the sensor performance. While the use of back-gating still grabs attention among the sensor community, top-gated and liquid-gated versions have started to dominate this area. The latest efforts on gFET designs for the sensing of nucleic acids, proteins and virus particles in different biofluids are presented herewith, highlighting the strategies presently engaged around gFET design and choosing the right bioreceptor for relevant biomarkers. [ABSTRACT FROM AUTHOR]

Achieving a low resistance contact is essential for developing two-dimensional (2D) material-based field-effect transistors (FETs). While n-type contacts to 2D semiconductors have been studied, understanding and designs for p-type contacts to 2D semiconductors remain very limited. In this study, we propose and computationally explore three strategies to improve the contact resistance in p-type 2D FETs, which remains a critical bottleneck of 2D logic technology, through the engineering of van der Waals (vdW) material heterostructures: (i) intercalating a graphene layer between a high-work-function metal and 2D semiconductor, which can result in low contact resistance of ~ 60 Ω μm for the graphene-intercalated contact between a high-work-function metal and WSe2 semiconductor; (ii) engineering the atomic stacking order between a vdW metal and 2D semiconductor, which can result in contact resistance of ~ 50 Ω μm; (iii) sandwiching the 2D layered semiconductor between vdW metals from both sides, which can further reduce the contact resistance to ~ 47 Ω μm and ~ 36 Ω μm for cases (i) and (ii), respectively. Experimental fabrication and characterization illustrate the feasibility of structural engineering of contacts. The above structural designs can lead to significantly reduced metal-induced gap states (MIGS) and low barrier height for holes, resulting in low contact resistance. They are also naturally compatible with the gate-all-around (GAA) transistor structure. In addition to contact materials selection, vdW structural design offers an alternative approach for achieving low contact resistance to p-type 2D FETs. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Over the last two decades, silicon nanowire field-effect transistors (SiNW-FETs) with prominent merits of high surface-to-volume ratio, excellent biocompatibility and mature fabrication with standard silicon technology, have been widely studied as ultrahigh sensitive biosensors for the detection of target biomolecules, such as proteins, nucleic acids, cells and viruses so on. Herein we present a comprehensive review of the fundamental aspects of SiNW-FET biosensors, involving the working principle and the device fabrication, surface functionalization, and system integration with fluid exchange and electrical detection. Futhermore, we emphatically discuss the electrical detection of cardiac-specific biomarkers related to acute myocardial infarction disease. SiNW-FET biosensors are being increasingly exploited as promising diagnostic devices, which provide high sensitivity, high integration density, high speed sampling, strong specificity, and real-time and label-free detection for simple and cheap clinical testing. [ABSTRACT FROM AUTHOR]

In this study, the graphene field-effect transistor (FET) has been created by depositing a film-forming suspension of reduced graphene oxide (RGO) on the silicon substrate with a SiO2 layer and air-drying at room temperature. The possibility of using the obtained FET for ionizing radiation detection was investigated. The electrical characteristics of the radiation sensor based on the RGO film were studied in modes of direct current and alternating current. The dependencies of the drain current and the resistance of the RGO film on the gate voltage of the obtained FET were analyzed. Linear sections on the dependence of the drain current on the gate voltage, the positions of which are determined by the sign of the drain-source voltage, were detected. A decrease in the conductivity of the FET based on the RGO film near the point of charge neutrality due to irradiation from the 226Ra isotope was established. An increase in resistance and a decrease in capacitance of the investigated FET have been found in the frequency range of 25 Hz – 1 MHz caused by the joint action of alpha and beta particles and gamma quanta. A linear dependence of the electrical characteristics of the proposed sensor on the adsorbed dose determined by the irradiation duration was discovered. Possible mechanisms of the ionizing radiation influence on the conductivity of the obtained structure based on the RGO film are considered. The generation of electron-hole pairs in the silicon substrate and the formation of radiation defects in the insulator layer are probably the main factors affecting the electrical characteristics of the RGO based FET under the action of ionizing radiation. The obtained results expand the perspective of using graphene FETs to create a new type of radiation detectors and diametric devices. [ABSTRACT FROM AUTHOR]

Tungsten diselenide ( WSe 2 ) has emerged as a promising ambipolar semiconductor material for field-effect transistors (FETs) due to its unique electronic properties, including a sizeable band gap, high carrier mobility, and remarkable on–off ratio. However, engineering the contacts to  WSe 2  remains an issue, and high contact barriers prevent the utilization of the full performance in electronic applications. Furthermore, it could be possible to tune the contacts to  WSe 2  for effective electron or hole injection and consequently pin the threshold voltage to either conduction or valence band. This would be the way to achieve complementary metal–oxide–semiconductor devices without doping of the channel material.This study investigates the behaviour of two-dimensional  WSe 2  field-effect transistors with multi-layer palladium diselenide ( PdSe 2 ) as a contact material. We demonstrate that  PdSe 2  contacts favour hole injection while preserving the ambipolar nature of the channel material. This consequently yields high-performance p-type  WSe 2  devices with  PdSe 2  van der Waals contacts. Further, we explore the tunability of the contact interface by selective laser alteration of the  WSe 2  under the contacts, enabling pinning of the threshold voltage to the valence band of  WSe 2 , yielding pure p-type operation of the devices. [ABSTRACT FROM AUTHOR]

Short‐wave infrared (SWIR) quantum dot (QD)‐converted photodetectors are one of the promising devices used in artificial intelligence and automatic navigation systems. However, compared to semi‐conductor‐type photodetectors, they suffer from poor chemical stability and weak electronic conductivity. In this study, a PbS QD and conductive metal–organic framework (MOF) hybrid composite is designed with SWIR detection capability. The Fourier‐transform infrared spectroscopy confirms the surface modification of PbS QDs with MOF. X‐ray absorption near‐edge structures spectra reveal the chemical bonding between MOF and PbS QDs. Furthermore, 2D grazing‐incidence small‐ and wide‐angle X‐ray scattering is utilized to unveil the particle stacking and the preferred orientation of the PbS@MOF thin film. By integrating the PbS@MOF thin film directly on top of the graphene field effect transistor (FET) device, the chemical stability and photoelectric properties of graphene FET are enhanced, and these are investigated using a focus ion beam with a high‐resolution transmission electron microscope. This study offers a strategy to simultaneously improve the chemical stability and the photoelectronic properties of the nanomaterials as well as contribute to the advancement of a QD‐converted SWIR photodetector. [ABSTRACT FROM AUTHOR]

A wearable sensor capable of directly detecting cytokines in external secretions external to the human body is pivotal for gauging the intensity of the immune response and circumventing inflammatory storms, a significant clinical concern. The detection of low‐concentration cytokines is often hampered due to interference from impurities in secretions. Addressing this challenge, a wearable detection system is developed by integrating a Janus membrane with water auto‐collection/filtering capabilities, and aptamer‐modified graphene field‐effect transistor sensors, enabling the detection of low‐concentration cytokines in undiluted sweat samples. The Janus membrane can automatically filter external secretions and transport them to the sensor surface, effectively eliminating impurity interference and enhancing the sensor's detection capabilities. The device can sensitively detect cytokines (such as TNF‐α, a marker for inflammation and cancer) in undiluted sweat, with a detection range spanning 0.5 to 500 pM, and a detection limit reaching 0.31 pM. The ultra‐flexibility of the sensor is also verified, maintaining stable electrical properties even after enduring up to 50 extreme deformations. These findings indicate that the wearable detection system has the potential to realize low‐concentration cytokines monitoring in the sweat of inflammatory patients, to assist the healthcare system in controlling the body's immune status. [ABSTRACT FROM AUTHOR]

In this work, an automatic thermoregulation system for biosensors based on field-effect transistors with a nanowire channel is demonstrated, providing full control and maintenance of the required temperature regime in bioanalytical analyses. The system elements, including field-effect transistors with a nanowire channel, temperature sensors, and heaters, were fabricated on a single silicon crystal using electron beam lithography, reactive ion etching, and high-vacuum deposition techniques. Unique electronics for temperature control and maintenance were developed. The dependence of thermometer readout on heating power was measured, which is in good agreement with the results of numerical simulation. A demonstration of a thermoregulation system with PID-feedback, ensuring the establishment of a desired temperature in the range from 30 to 70 C within 18 s in a liquid medium, was carried out. A demonstration of a thermoregulation system for detecting nucleic acids was performed using synthetic single-stranded DNA, representing a gene fragment from the bacterium Escherichia coli. The minimum detectable response was observed for a sample with a concentration of 3 fM. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Recently, there has been growing interest among researchers in developing efficient photorecording devices using perovskite (PVSK) materials as floating gate layers due to their simplified structure and noncontact, light-responsive characteristics. Since a PVSK-based memory layer can reduce the operating voltage of the device, it can be used for nonvolatile memory applications. Herein, the p-type material pentacene was utilized as the charge transport layer, while methylammonium lead bromide PVSK nanocrystals (NCs) were employed as the floating gate memory layer. Four types of poly-(amic acid) (PAA) polymers were synthesized in combination with PVSK for the memory layer. Compared to conventional polymers, PAA can further fine-tune the influence of energy-level alignment and the crystalline structure of PVSK NCs. The PAA structure consists of carboxylic acid and amide groups that can form Lewis acid–base interactions with PVSK NCs, while these hydrogen-bonding groups can interact with methylammonium to confine crystallite size, thereby passivating defects in PVSK NC films, providing structural stability and effectively optimizing device performance. Among the four synthesized PAA structures, sulfonyldianiline-cyclobutanetetracarboxylic dianhydride (SODA-CBDA) had a sulfone group and cyclobutane ring, possessing electron-withdrawing abilities that lowered the highest occupied molecular orbital level and a conjugation breaker that raised the lowest unoccupied molecular orbital level, resulting in a wider bandgap and stabilized electrons and holes compared to the other PAA structures. The fabricated device required only 1 s to complete electrical erasing and exhibited a stable and high ON/OFF current ratio (∼104) and long-term stability (>104 s) over consecutive device operations. [ABSTRACT FROM AUTHOR]

Two-dimensional (2D) van der Waals (vdW) p-type semiconductors have shown attractive application prospects as atomically thin channels in electronic devices. However, the high Schottky hole barrier of p-type semiconductor–metal contacts induced by Fermi-level pinning is hardly removed. Herein, we prepare a vdW 1T-CoS2 nanosheet as the contact electrode of a WSe2 field-effect transistor (FET), which shows a considerably high on/off ratio > 107 and a hole mobility of ∼114.5 cm2 V−1 s−1. The CoS2 nanosheets exhibit metallic conductivity with thickness dependence, which surpasses most 2D transition metal dichalcogenide metals or semimetals. The excellent FET performance of the CoS2-contacted WSe2 FET device can be attributed to the high work function of CoS2, which lowers the Schottky hole barrier. Our work provides an effective method for growing vdW CoS2 and opens up more possibilities for the application of 2D p-type semiconductors in electronic devices. [ABSTRACT FROM AUTHOR]

Developing new polymeric semiconductors with excellent device performance is essential for organic electronics. Herein, we synthesized two new thiazoloisoindigo (TzII)-based polymers, namely, P(TzII-dTh-dTh) and P(TzII-dTh-dTz), by copolymerizing thiophene-flanked TzII with bithiophene and bithiazole, respectively. Owing to the more electron-deficient nature of bithiazole than bithiophene, P(TzII-dTh-dTz) possesses deeper LUMO/HOMO levels of −3.45/−5.47 eV than P(TzII-dTh-dTh) (−3.34/−5.32 eV). The organic field-effect transistor (OFET) devices based on P(TzII-dTh-dTh) exhibited p-type behaviors with an average hole mobility value as high as 1.43 cm2·V−1·s−1, while P(TzII-dTh-dTz) showed typical ambipolar characteristics with average hole and electron mobilities of 0.38 and 0.56 cm2·V−1·s−1. In addition, we compared the performances of both polymers with other TzII-based polymers reported in our previous work, and showed that the charge carrier polarity can be manipulated by adjusting the number of the thiophene units between the acceptor unit. As the increase of the number of thiophene rings, charge carrier polarity shifts from electron-dominated ambipolar transport to hole-dominated ambipolar transport and then to unipolar hole transport in OFETs, which provides an effective molecular design strategy for further optimization of polymer OFET performance. [ABSTRACT FROM AUTHOR]

This study suggests the Pd-doped porous silicon (PS)–reduced graphene oxide (rGO) hybrid structures to create a photosensitive field-effect transistor. I-V curves and switching characteristics of the created graphene field-effect transistors were analyzed. A significant effect of the supporting porous layer on the transfer of charge carriers in the graphene film was established. A decrease in internal resistance and an increase in the capacitance of the hybrid structures due to photogenerated charge carriers were found. The parameters of the equivalent circuit model of the Pd-doped PS–rGO under the influence of irradiation were determined based on the impedance spectra. [ABSTRACT FROM AUTHOR]

Bitterness elicits unpleasant sensations in humans, which can hinder the acceptance of foods and medication adherence. Therefore, identifying and masking bitter tastes is crucial for developing palatable foods and promoting medication compliance in the food and pharmaceutical industries. To achieve this, employing agonism and antagonism of bitter taste receptors as effective strategies at the molecular level is essential. In this study, a bioelectronic tongue is developed to characterize the agonism and antagonism of bitter taste receptors. The human bitter taste receptors hTAS2R16 and hTAS2R31 are produced using an Escherichia coli expression system and reconstituted into nanodiscs (NDs). Subsequently, hTAS2R16‐ and hTAS2R31‐NDs are immobilized on the surface of graphene field‐effect transistors (FETs) to construct bioelectronic tongues. The developed system sensitively detected the bitter agonists, salicin and saccharin, at concentrations as low as 100 fM, with high selectivity in real‐time. The dose‐dependent curves shifted and K values decreased by the antagonists of hTAS2R16 and hTAS2R31, indicating antagonism‐based masking of bitter taste. Therefore, the developed bioelectronic tongue holds promise for identifying bitter tastes and evaluating the masking of bitterness based on the agonism and antagonism of hTAS2Rs. [ABSTRACT FROM AUTHOR]

In this study, the field-effect transistor (FET) based on the oxidized porous silicon (PS) -- reduced graphene oxide (rGO) sandwich-like composite has been created. The electrical characteristics of the obtained FET were studied in both DC and AC modes. I-V curves and switching characteristics of the PS--rGO-based FET were analyzed. An increase in resistance and a decrease in capacitance of the experimental structures have been found in the 25 Hz -- 1MHz frequency range due to the joint action of a-, b-, and c-radiation. The parameters of the equivalent circuit model of the PS--rGO-based FET before and after irradiation with 226Ra isotope have been determined using the impedance spectra. The formation of radiation-induced defects and the charge accumulation in the PS layer is considered a possible mechanism of the ionizing radiation influence on the graphene FET conductivity. The FET based on the PS--rGO structures has a high potential for application in ionizing radiation sensors due to the linear dependencies of resistance and capacitance on the irradiation duration. [ABSTRACT FROM AUTHOR]

This study presents a comparative analysis between physical doping and electrochemical doping techniques in thin-film transistors using conjugated semiconducting polymer films. Two types of polymer films were investigated as the active layer in the transistors: a semi-crystalline semiconducting polymer, specifically poly(2,5-bis(3-tetradecylthiophen-2yl)thieon(3,2-b)thiophene) (PBTTT), and an amorphous-like donor–acceptor (D–A)-type conjugated copolymer, namely poly[2,5-(2-octyldodecyl)-3,6- diketopyrrolopyrrole-alt-5,5-(2,5-di(thien-2-yl)thieno[3,2-b]thiophene)] (PDPP-2T-TT). The physical doping of molecular dopants was characterized using a field-effect transistor platform with a neutral molecular-doped polymer film as the active layer. The degree of doping was manipulated by varying the exposure time to tetrafluoro-tetracyanoquinodimethane molecules. In parallel, the electrochemical doping process was evaluated using electrolyte-gated transistors (EGT), where the electrolyte comprised an ion gel composed of a polymer network swollen with an ionic liquid. The doping concentration in the active layer of the EGT was assessed in a gate bias-dependent manner by analyzing the gate current curves upon gate-bias. Interestingly, the physical molecular doping process was more effective in highly crystalline thiophene polymers, such as PBTTT, than the amorphous D–A type copolymers. Conversely, the electrochemical doping process exhibited higher efficiency in the disordered PDPP-2T-TT film compared to the PBTTT film. Structural and optical analysis, utilizing X-ray diffraction and UV–Vis spectroscopy, suggests that the charge transfer between the polymer semiconductor and the dopant is profoundly influenced by the structural characteristics and energy level of the polymer semiconductor. This study examines the effects of physical and electrochemical doping on polymer thin-film transistors and assess their influence on doping efficiency and device performance. It offers valuable insights for optimizing doping strategies in semiconducting polymer systems. [ABSTRACT FROM AUTHOR]

Ultraviolet-ozone (UV-O3) treatment is a simple but effective technique for surface cleaning, surface sterilization, doping, and oxidation, and is applicable to a wide range of materials. In this study, we investigated how UV-O3 treatment affects the optical and electrical properties of molybdenum disulfide (MoS2), with and without the presence of a dielectric substrate. We performed detailed photoluminescence (PL) measurements on 1–7 layers of MoS2 with up to 8 min of UV-O3 exposure. Density functional theory (DFT) calculations were carried out to provide insight into oxygen-MoS2 interaction mechanisms. Our results showed that the influence of UV-O3 treatment on PL depends on whether the substrate is present, as well as the number of layers. Additionally, 4 min of UV-O3 treatment was found to be optimal to produce p-type MoS2, while maintaining above 80% of the PL intensity and the emission wavelength, compared to pristine flakes (intrinsically n-type). UV-O3 treatment for more than 6 min not only caused a reduction in the electron density but also deteriorated the hole-dominated transport. It is revealed that the substrate plays a critical role in the manipulation of the electrical and optical properties of MoS2, which should be considered in future device fabrication and applications. [ABSTRACT FROM AUTHOR]