Field-effect Transistors Research Articles

Carrier Mobility Enhancement in Ultrathin-Body InGaAs-on-Insulator n-Channel Metal-Oxide-Semiconductor Field-Effect Transistors Based on Dual-Gate Modulation

As a promising candidate for More Moore technology, InGaAs-based n-channel metal-oxide-semiconductor field-effect transistors (nMOSFETs) have attracted growing research interest, especially with InGaAs-on-insulator (InGaAs-OI) configurations aimed at alleviating the short channel effects. Correspondingly, the fabrication of an ultrathin InGaAs body becomes necessary for the full depletion of the channel, while the deteriorated semiconductor–insulator interface-related scattering could severely limit carrier mobility. This work focuses on the exploration of carrier mobility enhancement strategies for 8 nm body-based InGaAs-OI nMOSFETs. With the introduction of a bottom gate bias on the substrate side, the conduction band structure in the channel was modified, relocating the carrier wave function from the InGaAs/Al2O3 interface into the body. Resultantly, the channel mobility with an inversion layer carrier concentration of 1 × 1013 cm−2 was increased by 62%, which benefits InGaAs-OI device application in monolithic 3D integration. The influence of the dual-gate bias from front gate and bottom gate on gate stability was also investigated, where it has been unveiled that the introduction of the positive bottom gate bias is also beneficial for gate stability with an alleviated orthogonal electric field.

Structural and dynamical properties of two dimensional disordered metal chalcogenides AB (A [formula omitted] Zn, Cd; B [formula omitted] S, Se): A classical molecular dynamic study

In recent years, the synthesis of two-dimensional (2D) materials, particularly the crystalline and disordered phases of 2D transition metal chalcogenides (TMCs), has gained considerable attention due to their wider electronic band gaps. This distinctive feature is pivotal in shaping their potential applications in solar cells, sensors, field-effect transistors (FETs), and photocatalysis for water decomposition. In the present study, we report molecular dynamics simulation of 2d disordered configuration of ZnX and CdX (X: S, Se) compounds using the Stillinger–Weber potential. We have explored their structural features by calculating their radial distribution functions and ring statistics. These systems are thermodynamically stable. The disordered network with numerous voids in these compounds play a pivotal role in lowering their melting temperature compared to their 2D crystalline counterparts, which falls within the range of 600 K to 700 K. The phonon density of states for all these systems shows a higher number of lower frequency (acoustic) modes than optical modes, which is understandably due to the presence of open regions and 2-fold sites in such systems.

Amplification‐free sub-femtomolar monitoring of SARS-CoV-2-RNA in serum samples using cDNA-modified MoS2 field-effect transistor

The rapid spread of infectious diseases, exemplified by the well-known case of COVID-19, which has led to a global pandemic, has garnered increasing attention toward the development of simple and efficient biosensors for diagnosis. In this study, a field-effect transistor (FET)-based biosensor offers an alternative and promising solution for the diagnosis of clinical COVID-19. Molybdenum disulfide (MoS2) in a channel FET modified with a probe complementary DNA (cDNA) can sensitively detect selected specific sequences from SARS-CoV-2 through hybridization. MoS2 was modified with probe cDNA and exhibited a linear concentration range of 1 fM to 0.1 nM in both phosphate-buffered saline (PBS) and serum samples, with low limits of detection (LOD) of 0.21 and 0.73 fM, respectively. In addition, it demonstrated a rapid response time of 3 min in clinical samples. The developed biosensor is capable of analyzing RNA from 19 clinical samples. These results indicate that the biosensor successfully distinguished between healthy and infected samples, which is consistent with the RT-PCR results (kappa coefficient = 1). Additionally, a notable difference was observed between the RdRp samples of SARS-CoV-2 and SARS-CoV. Therefore, we believe that this study offers a reliable and appealing option for the diagnosis of COVID-19.

Mercury-probe measurement of electron mobility in β-Ga2O3 using junction moderated dielectric relaxation

We demonstrate the junction-moderated dielectric relaxation method to measure the in-plane electron mobility in β-Ga2O3 epitaxial layers. Unlike the Hall technique and channel mobility measurement in field-effect transistors, this method does not require the deposition of permanent metal contacts. Rather, it measures the bias voltage and frequency dependence of the equivalent capacitance of the Mercury/β-Ga2O3/Mercury structure consisting of a Schottky contact, a quasi-neutral thin film semiconductor, and an Ohmic contact connected in series. The intrinsic dielectric relaxation of the bulk β-Ga2O3 semiconductor typically occurs at ∼1012 s−1, but when moderated by the Mercury/β-Ga2O3 Schottky junction, it manifests itself as an inflection in the capacitance-frequency characteristics at a much lower frequency of ∼106 s−1 within the range of most capacitance measuring instruments. Using carrier density and layer thickness determined from capacitance-voltage measurement, we extract the electron mobility of β-Ga2O3 from the junction-moderated dielectric relaxation frequency.

Wearable and Multiplexed Biosensors based on Oxide Field-Effect Transistors.

Wearable sensors designed for continuous, non-invasive monitoring of physicochemical signals are important for portable healthcare. Oxide field-effect transistor (FET)-type biosensors provide high sensitivity and scalability. However, they face challenges in mechanical flexibility, multiplexed sensing of different modules, and the absence of integrated on-site signal processing and wireless transmission functionalities for wearable sensing. In this work, a fully integrated wearable oxide FET-based biosensor array is developed to facilitate the multiplexed and simultaneous measurement of ion concentrations (H+, Na+, K+) and temperature. The FET-sensor array is achieved by utilizing a solution-processed ultrathin (≈6nm thick) In2O3 active channel layer, exhibiting high compatibility with standard semiconductor technology, good mechanical flexibility, high uniformity, and low operational voltage of 0.005V. This work provides an effective method to enable oxide FET-based biosensors for the fusion of multiplexed physicochemical information and wearable health monitoring applications.

Multiphysics Simulation of Self-Heating-Induced Thermal Stress Effects on Quantum Transport in Gate-All-Around Nanosheet Field Effect Transistors

Multiphysics Simulation of Self-Heating-Induced Thermal Stress Effects on Quantum Transport in Gate-All-Around Nanosheet Field Effect Transistors

Simulation Study on Comparison of “Inside-Channel” and “On-Dielectric” Source Contact Modifications on the Performance of the Vertical Organic Field Effect Transistors

Simulation Study on Comparison of “Inside-Channel” and “On-Dielectric” Source Contact Modifications on the Performance of the Vertical Organic Field Effect Transistors

Agent-free, highly sensitive, and simply operated Ag+ sensor with molybdenum disulfide-based field effect transistor

Agent-free, highly sensitive, and simply operated Ag+ sensor with molybdenum disulfide-based field effect transistor

Field Effect Transistor Biosensors for Healthcare Monitoring (4/2024)

Field Effect Transistor Biosensors for Healthcare Monitoring (4/2024)

New family of two-dimensional A2B2C5 single-layer with high carrier mobilities and excellent conversion efficiency for solar cells

Screening high-performance two-dimensional (2D) materials with desirable direct band gaps and high mobility has attracted great interest due to their excellent application in 2D field effect transistors. Herein, we predicted a new family of nine-atomic A2B2C5 (A = Mg, Ba; B= Al, Ga, and In, C = S, Se) single-layer using first-principles calculations. The results indicate that the energies of this A2B2C5 single-layer are slightly lower than that of exfoliated single-layer Mg2Al2S5. Furthermore, most of the A2B2C5 single-layers host not only direct band gaps but also outstanding electron mobilities (up to ∼103 cm2V−1s−1), revealing a desirable range of near-infrared to visible light absorption. Importantly, single-layer Ba2Al2Se5 and Mg2Ga2Se5 are good donor materials, the corresponding Ba2Al2Se5/HfS2 and Mg2Ga2Se5/InS type-II heterostructures exhibit promising power conversion efficiencies of 22.3 % and 19.8 %, respectively. Our work provides some competitive A2B2C5 candidate single-layers for applying high-performance solar cells.

Performance assessment of SiGe extended four corner source TFET for biosensing applications

In this paper, the performance of a novel SiGe extended four corner source tunneling field–effect transistor (SiGe EFCS TFET) based dielectrically modulated label-free biosensor has been investigated for biosensing applications. Using a combination of heterostructure (SiGe/Si) and extended four corner source (EFCS) lead to increased band–to–band tunneling (BTBT) probability, improved gate control and superior drain current sensitivity for biomolecule conjugation in comparison with a conventional TFET and Si EFCS TFET structures of similar dimensions. The influence of both the charge–neutral and charged biomolecules on the sensitivity performance is investigated using the Silvaco TCAD ATLAS semiconductor device simulator with a calibrated nonlocal BTBT model. Four different kinds of biomolecules such as Streptavidin, Ferro–cytochrome c, Keratin and Gelatin with various charge density values were used for this purpose. In order to model steric hindrance effects in partially filled cavities, in addition to various fill factors, four different step profile patterns have considered such as convex, concave, decreasing and increasing step profiles. Also, the dependence of the nanogap cavity properties on the sensing performance in terms of the length and thickness is investigated. A maximum drain current sensitivity of 1.69 × 105 is achieved in SiGe EFCS TFET for Gelatin biomolecules in a fully filled nanogap cavity at overdrive and drain voltages of 0.5 V.

Tuning of Gate Electrostatics to Amplify Mercury Sensing Performance of Functionalized Field Effect Transistor

Tuning of Gate Electrostatics to Amplify Mercury Sensing Performance of Functionalized Field Effect Transistor

Analysis of voltage mode quadrature oscillator based on fin field-effect transistor

This study introduces a new voltage mode sinusoidal quadrature oscillator (V-M.S.Q.O.) that employs multioutput Z copy voltage differencing transconductance amplifiers (M-Zc-VDTA) as an active filter based on FinFET transistor. The suggested circuits have low passive and active sensitivities, and they may be constructed as integrated circuits using only two M-Zc-VDTAs and three grounded capacitors. The circuits produce two (VM) sinusoidal quadrature oscillator voltage results by adjusting the electronic base current and frequency of the oscillation condition separately. FinFET technology lowers power consumption while improving circuit performance. They can also produce amplitude shift keying-amplitude modulation signals for communication electronics systems and provide electrical basis control of output current amplitude. Using the Cadence Virtuoso tool with a 7 nm parameter, simulation results were obtained for the suggested circuits.

Elucidating the time-dependent charge neutrality point modulation of polymer-coated graphene field-effect transistors in an ambient environment.

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/SiO2interface. 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.

High-voltage kV-class AlN metal-semiconductor field-effect transistors on single-crystal AlN substrates

This letter reports the demonstration and electrical characterization of high-voltage AlN metal-semiconductor field-effect transistors (MESFETs) on single-crystal AlN substrates. Compared with AlN MESFETs on foreign substrates, the AlN-on-AlN MESFETs showed high breakdown voltages of over 2 kV for drain-to-gate spacing of 15 μm and one of the highest average breakdown fields among reported AlN MESFETs. Additionally, the devices also exhibited decent drain saturation current and on/off ratio without complicated regrown or graded contact layers, which are several times higher than those of reported AlN-on-sapphire MESEFTs. This work is beneficial for the future development of ultrawide bandgap AlN power electronics.

An analytical I-V model of SiC double-gate junctionless MOSFETs

Silicon carbide(SiC) double gate junctionless metal oxide semiconductor field-effect transistors(DG JL MOSFETs) have attracted significant attention due to their ideal high temperature characteristics and radiation resistance. Therefore, it is meaningful to exploit an I-V model for SiC DG JL MOSFETs. In this article, we make a linear approximation to describe the relationship between the surface mobile charge density and the surface electron concentration of the device. Based on this approximation and using the one-dimensional Poisson’s equation, we solve for the potential distribution of a SiC DG JL MOSFET in the subthreshold region. From this solution, we derived a functional relationship between the surface mobile charge density in the channel and the channel quasi-Fermi potential. Then we successfully developed a unified I-V model for the SiC DG JL MOSFETs. Based on the drain to source current calculation formula, the calculation expressions for the device’s transconductance and output conductance are derived. By comparing our model with the results from the two-dimensional numerical simulation software Silvaco Atlas, our model’s calculations closely match the two-dimensional numerical simulation results from the subthreshold region to the accumulation region. This model has reference significance for SiC DG JL MOSFETs in the high temperature electronic circuit application field.

Luminophores based on 2<i>H</i>-1,2,3-triazoles: synthesis, photophysical properties, and application prospects

The review systematizes the data on the synthesis of 2<i>H</i>-1,2,3-triazole-based luminophores published between 2005 and the beginning of 2024. The benefits and limitations of the described synthetic strategies are revealed. The possibilities and prospects for the practical applications of these molecular systems as chemosensors for pH and metal ion determination, bioimaging agents, and working elements of molecular electronic devices (organic light emitting diodes, organic field-effect transistors, <i>etc.</i>) are discussed. <br>The bibliography includes 84 references.

Optimization of test methods and algorithms for assessing the resistance of field-effect transistors to various types of radiation using promising test equipment

Optimization of test methods and algorithms for assessing the resistance of field-effect transistors to various types of radiation using promising test equipment

Improved Subthreshold Characteristics of Epi-Silicon FinFET via Fin Surface Passivation Technologies

As demand for advanced integrated circuits (ICs) continues to grow, fin field-effect transistors (FinFETs) have remained highly influential in the IC market because of their mature fabrication process and powerful driving capabilities. However, the ion bombardment that occurs during the reactive ion etching (RIE) process used to form the fin structure increases the fin’s surface roughness and results in a high interfacial state density (D it ), which hinders further improvement in the subthreshold swing (SS) of FinFETs. To overcome this issue, this study proposes two oxidative trimming methods for use on the fin structures to improve their interface quality. It is found that conventional thermal oxidation and low-temperature oxidation processes reduced the channel D it by 73.31% vs 71.17%, respectively. Furthermore, the corresponding SS values of the device improved to 72.76 and 71.72 mV dec−1, respectively. The technical solutions proposed in this paper represent a promising approach for performance optimization of FinFETs and other advanced devices.

Accelerating Linear Congruential Generators with Carbon Nanotube Field-Effect Transistors

Abstract In the era of technological advancements, safeguarding information privacy has become paramount across sectors like defense, finance, healthcare, and more. At the heart of these security measures lies cryptography, a field that necessitates the efficient processing and secure storage of data. Our project focuses on the optimization of Linear Congruential Generators (LCG), pivotal for cryptographic applications and pseudorandom number generation. Here it has been pioneered the implementation of LCG using Carbon Nanotube Field-Effect Transistor (CNTFET) technology, targeting the reduction of leakage power through the innovative application of sleep techniques. This advanced approach not only embodies a leap towards minimizing energy consumption but also enhances the overall performance and reliability of cryptographic systems. By integrating sleep modes into the CNTFET-based LCG design, our methodology significantly curtails leakage power without compromising the generator’s efficiency or output quality. The successful implementation and synthesis of this design, employing cutting-edge CNTFET technology, underscore the potential for substantial improvements in power efficiency while maintaining high standards of security and randomness essential for cryptographic algorithms.