Field Effect Transistor Type Research Articles

A Carbon Nanotube Sensor Array for the Label-Free Discrimination of Live and Dead Cells with Machine Learning

Developing robust cell recognition strategies is important in biochemical research, but the lack of well-defined target molecules creates a bottleneck in some applications. In this paper, a carbon nanotube sensor array was constructed for the label-free discrimination of live and dead mammalian cells. Three types of carbon nanotube field-effect transistors were fabricated, and different features were extracted from the transfer characteristic curves for model training with linear discriminant analysis (LDA) and support-vector machines (SVM). Live and dead cells were accurately classified in more than 90% of samples in each sensor group using LDA as the algorithm. The recursive feature elimination with cross-validation (RFECV) method was applied to handle the overfitting and optimize the model, and cells could be successfully classified with as few as four features and a higher validation accuracy (up to 97.9%) after model optimization. The RFECV method also revealed the crucial features in the classification, indicating the participation of different sensing mechanisms in the classification. Finally, the optimized LDA model was applied for the prediction of unknown samples with an accuracy of 87.5-93.8%, indicating that live and dead cell samples could be well-recognized with the constructed model.

A New Type of Tri-Input TFET with T-Shaped Channel Structure Exhibiting Three-Input Majority Logic Behavior

In this paper, we propose a new type of tri-input tunneling field-effect transistor (Ti-TFET) that can compactly realize the “Majority-Not” logic function with a single transistor. It features an ingenious T-shaped channel and three independent-biasing gates deposited and patterned on its left, right, and upper sides, which greatly enhance the electrostatic control ability between any two gates of all the three gates on the device channel and thus increase its turn-on current. The total current density and energy band distribution in different biasing conditions are analyzed in detail by TCAD simulations. The turn-on current, leakage current, and ratio of turn-on/off current are optimized by choosing appropriate work function and body thickness. TCAD simulation results verify the expected characteristics of the proposed Ti-TFETs in different working states. Ti-TFETs can flexibly be used to implement a logic circuit with a compact style and thus reduce the number of transistors and stack height of the circuits. It provides a new technique to reduce the chip area and power consumption by saving the number of transistors.

Interface Trap Suppression and Electron Doping in Van der Waals Materials Using Cross-Linked Poly(vinylpyrrolidone).

The instability of van der Waals (vdW) materials leads to spontaneous morphological and chemical transformations in the air. Although the passivation of vdW materials with other resistive materials is often used to solve stability issues, this passivation layer can block carrier injection and thus interfere with charge transfer doping. In this study, a facile method is proposed for n-doping and mediation of Se vacancies in tungsten diselenide (WSe2) by poly(vinylpyrrolidone) (PVP) coating. The major carrier type of the PVP-coated WSe2-based field-effect transistor (FET) was converted from hole (p-type) to electron (n-type). Furthermore, the vacancy-induced interface trap density was reduced by approximately 500 times. This study provides a practical doping and passivation method for the van der Waals materials, as well as a comprehensive understanding of the chemical reaction and electronic transport in these materials.

Electrochemical Biosensing of Dopamine Neurotransmitter: A Review.

Neurotransmitters are biochemical molecules that transmit a signal from a neuron across the synapse to a target cell, thus being essential to the function of the central and peripheral nervous system. Dopamine is one of the most important catecholamine neurotransmitters since it is involved in many functions of the human central nervous system, including motor control, reward, or reinforcement. It is of utmost importance to quantify the amount of dopamine since abnormal levels can cause a variety of medical and behavioral problems. For instance, Parkinson’s disease is partially caused by the death of dopamine-secreting neurons. To date, various methods have been developed to measure dopamine levels, and electrochemical biosensing seems to be the most viable due to its robustness, selectivity, sensitivity, and the possibility to achieve real-time measurements. Even if the electrochemical detection is not facile due to the presence of electroactive interfering species with similar redox potentials in real biological samples, numerous strategies have been employed to resolve this issue. The objective of this paper is to review the materials (metals and metal oxides, carbon materials, polymers) that are frequently used for the electrochemical biosensing of dopamine and point out their respective advantages and drawbacks. Different types of dopamine biosensors, including (micro)electrodes, biosensing platforms, or field-effect transistors, are also described.

Universal Filter Design Using 45 nm FinFET Technology-Based Floating Current Source

ABSTRACT Fin type Field Effect Transistor (FinFET) technology is a promising technology for single-digit nanometric dimensions. FinFETs are used to increase the performance by reducing the power consumption as the two gate voltages are controlled dependent and/or independently. This work explores the design of a Floating Current Source (FCS) using Double Gate (DG) FinFET and its application of a universal filter. The designed FinFET based FCS operates at 0.15 V power supply, the power consumption of the circuit is 51nW and bandwidth is approximately 100 MHz. The proposed FCS based filter circuit is simulated in LTspice with the FinFET 45 nm PTM-MG model. The filter topology behavior has been tested with an experimental study using the LM13700 integrated circuit and the experimental results are demonstrated. The proposed FinFET based circuit and its application can be used for the design of systems that require low power consumption and low chip area.

Use of doping to achieve low contact resistance in bottom-gate top-contact type organic transistor with liquid-crystalline organic semiconductor, Ph-BTBT-10

We have investigated the characteristics of bottom-gate and top-contact type field effect transistors fabricated with polycrystalline thin films of a liquid-crystalline organic semiconductor, 2-decyl-7-phenyl-benzothienobenzothiophene (Ph-BTBT-10), with a p-type dopant, tetrafluoro-tetracyano-quinodimethane (F4-TCNQ). We found that the contact resistance between the semiconductor and electrode was reduced from 3.0 kΩ cm to 1.2 kΩ cm by contact doping with F4-TCNQ, and to 0.9 kΩcm by subsequent thermal annealing of the films, in which the F4-TCNQ dopant diffused from the surface to the interior of the Ph-BTBT-10 thin film. In addition, we found that contact-doped and thermally annealed devices showed higher mobility and smaller threshold voltage in short-channel devices compared to pristine devices. We conclude that thermal diffusion of dopants to improve FET performance is an important technique.

Simulation study on lateral minority carrier transport in the surface inversion layer of the p-aSi:H/i-aSi:H/cSi heterojunction solar cell

The theoretical lateral current of the surface inversion layer in a crystalline silicon (cSi) surface for a p-aSi:H/i-aSi:H/cSi heterojunction (SHJ) solar cell was calculated using computer simulation and was compared with the experimental one to study defects/traps at the aSi:H/cSi interface and/or in the cSi surface and to detect the acceptor concentration (N a) in p-aSi:H. To experimentally extract the lateral surface inversion layer current, a field-effect transistor type test element group device was co-integrated with SHJ cells on the same wafer. From the correlation between the experimental and calculated lateral surface inversion layer current, the density of defects/traps (D it) at the aSi:H/cSi interface and/or in the cSi surface and the value of N a were extracted. The calculated lateral surface inversion layer current stayed unchanged for various minority carrier lifetimes in the substrate, suggesting that this method is not suffered from the variation in the material parameters in the substrate.

2-Dimensional Ga2O3 Based Field Effect Transistor for Hydrogen Sensing Application

β-phase gallium oxide (β-Ga2O3) has attracted a lot of interest for the applications of high-power electronics, gas sensors, and solar-blind photodetectors. β-Ga2O3 is an alternative semiconducting material for high-power and high-temperature devices due to a large bandgap energy of 4.9 eV and high critical breakdown field (> 8 MV/cm). The Baliga’s figure of merit is 3400, which is 4-10 times higher than those of GaN and SiC. Ga2O3 based devices is expected to be more efficient with reduced size and high level of integration because the theoretical on-state resistance is almost one order magnitude lower than those of GaN and SiC devices at the same breakdown voltage. When compared to GaN and SiC, single crystal Ga2O3 wafers are available at low cost with floating zone and the edge-defined film-fed growth methods. The monoclinic β-Ga2O3 is the most stable form among five different crystal phases of Ga2O3. The large lattice constant of 12.23 Å of β-Ga2O3 along [100] direction enables to achieve the facile cleavage of β-Ga2O3 crystal into 2-dimensional flake though β-Ga2O3 is not a Van der Waals material. The thin channel of Ga2O3 flake is beneficial to the FET (field effect transistor) type gas sensor. In this study, the fabrication of 2-dimensional β-Ga2O3 flake based field effect transistor and its hydrogen sensing characteristics for hydrogen sensor application will be presented.

Effect of Temperature on the Performance of an Ion-Sensitive Field-Effect Transistor-Type Chemical Sensor with Aluminum Nitride Membrane

ISFET chemical sensors offer innovative solutions for the detection of chemical species by optimizing the ionosensitive membrane or layer between the aqueous medium and the insulation. As a result, the information provided by the sensor is no longer reliable. This is a major problem, as operators are often required to take measurements in an environment with higher or lower temperatures. The study of the effect of temperature on the detection parameters of the sensor, which are the surface potential, linearity and sensitivity, seems essential. The mathematical model presented in this article describes the physicochemical and thermal behavior of the sensor. First, it allows a series of simulations to be carried out on the variation in sensitivity, potential, and linearity with respect to the variation in pH. The second part of this work concerns the influence of temperature on the behavior of the sensor. Hence the determination of the temperature coefficient of the sensitivity, which is an indication of the performance of the sensor. It is also noted that the nature of the membranes of the sensors (Si3N4, Al2O3, SnO2) influences the temperature coefficient.

Ultrafast H2 gas nanosensor for ppb-level H2 gas detection based on GaN honeycomb nanonetwork

Material architecture design plays a crucial role in developing gas sensors. GaN has been proposed as a promising material for H2 gas sensor. However, it is subject to long response time and large low limit of detection (LOD).via spherical metal pattern technology, honeycomb can be created in GaN nanostructure but has yet to be explored. Herein, the GaN honeycomb nanonetwork was utilized to fabricate a field effect transistor (FET) type hydrogen (H2) gas nanosensor and its H2 gas sensing performances were systematically investigated. Through the combination of the novel honeycomb nanonetwork with the field effect modulation, we demonstrate high performance H2 gas sensor with wide detection concentration range, fast response, and small LOD. It is worth noting that the response time for H2 gas is very fast, as short as ≤3 s. Most importantly, the LOD for this FET type sensor is as small as ∼ 34 ppb. Density functional theory (DFT) calculation was utilized to study the H2 gas sensing mechanism. Significant reduction of Schottky barrier and improvement of the tunneling probability of the Pt-GaN metal-semiconductor interface were observed. Finally, a model is proposed to explain the H2 gas sensing mechanism.

A New Simulation Approach of Transient Response to Enhance the Selectivity and Sensitivity in Tunneling Field Effect Transistor-Based Biosensor

In this work, a new simulation approach of transient analysis on single cavity dielectric-modulated (DM) p -type of tunnel field-effect transistor (TFET) is examined for biosensing applications. The device operation and performance are investigated using the 2D device simulator and results are well-calibrated with experimental data. In this work, we have examined DC transfer characteristics, the transient response of drain current, drain current sensitivity (S), and selectivity (AS). Focussing more on the transient results, we have obtained maximum sensitivity of orders greater than 108 for APTES biomolecule with respect to air and a significant selectivity value in orders of 103 for APTES with respect to Biotin biomolecule. The performance of the device in terms of selectivity can be further improved (~10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</sup> ) by optimizing the back-gate bias, and therefore, the impact of back-gate bias has been analysed. The results for charged biomolecules and partially filled cavity are further investigated & highlighted. The DM p-TFET biosensor shows a significant improvement in the results with the transient response for biosensing applications with the feasibility of operating at low voltages (gate voltage of -2.0 V, drain voltage of -0.5 V and back gate voltage 0 to 0.5 V).

Effects of CF4 Plasma Treatment on Indium Gallium Oxide and Ti-doped Indium Gallium Oxide Sensing Membranes in Electrolyte–Insulator–Semiconductors

Electrolyte–insulator–semiconductor (EIS) sensors, used in applications such as pH sensing and sodium ion sensing, are the most basic type of ion-sensitive field-effect transistor (ISFET) membranes. Currently, some of the most popular techniques for synthesizing such sensors are chemical vapor deposition, reactive sputtering and sol-gel deposition. However, there are certain limitations on such techniques, such as reliability concerns and isolation problems. In this research, a novel design of an EIS membrane consisting of an optical material of indium gallium oxide (IGO) was demonstrated. Compared with conventional treatment such as annealing, Ti doping and CF4 plasma treatment were incorporated in the fabrication of the film. Because of the effective treatment of doping and plasma treatment, the defects were mitigated and the membrane capacitance was boosted. Therefore, the pH sensitivity can be increased up to 60.8 mV/pH. In addition, the hysteresis voltage can be improved down to 2.1 mV, and the drift voltage can be suppressed to as low as 0.23 mV/h. IGO-based membranes are promising for future high-sensitivity and -stability devices integrated with optical applications.

Eco-friendly collagen-based bio-organic field effect transistor with improved memory characteristics

Abstract With the miniaturization race, organic field-effect transistor (OFET) devices have gained much attention in recent years due to their advantages of flexibility, light weight, solution processability and low manufacturing cost. However, some inorganic or organic materials are eco-unfriendly. Therefore, in this study, the natural biological proteins collagen hydrolysate acts as dielectric material due to the presence of hydroxyl groups. Cationic surfactant hexadecyltrimethylammonium chloride (CTMA) is added into collagen hydrolysate to form a dielectric layer in bio thin film transistor (BioTFT) device. Experimental results highlight that the collagen-CTMA mixture at 3 wt% (Col-CTMA3) has shown an average mobility of 3.36 × 10−2 cm2V−1s−1 and an on/off ratio up to 2.7 × 106.1-aminopyrene is embedded into Col-CTMA3 mixture to form Col-CTMA3-1-aminopyrene (Col-CTMA3-AP) mixture to fabricate bio field-effect transistor (BioFET) type memory device. Furthermore, the optimized addition of 1-aminopyrene in the Col-CTMA3-AP mixture for memory device has provided enhanced performances associated to an average mobility of 1.23 × 10−2 cm2V−1s−1, an on/off ratio up to 5.22 × 105 and a memory window of 13.6 V, as the proportion of 1-aminopyrene increased, the charge-trapping ability of collagen strengthened. Environment effect studies have shown that BioFET memory devices placed under water environment highlight the role of the hydroxyl group for the improved BioFET performance.

Architectures of Graphene-Based Field-Effect Transistors for Single-Molecule Experiments

With progress in the extreme miniaturisation of electronic components and the discovery of low-dimensional conductive materials, it is now possible to assemble field-effect transistors (FETs) that can incorporate single-molecule components as a channel or gate1,2. Such types of FETs have been recently used to detect and study various fundamental mechanisms at the single-molecule scale, among which the folding and unfolding of molecules, hybridization mechanisms, charge transport or chemical reactions1–5. In these experiments, devices were typically fabricated using architectures based on individual 1D materials, such as carbon nanotubes (CNTs) and silicon nanowires. The 1D topology facilitates the isolation of individual molecules in the circuit, but present drawbacks in scalability due to challenges in the growth, purification and/or assembling of such 1D materials into FET circuits. Here, we present new top-down approaches for the fabrication of single-molecule FETs, based on 2D graphene architectures. As CNTs, graphene is made of an hexagonal carbon lattice enabling excellent conductivity as well as carbon-based chemistry to anchor individual molecules, yet its 2D topology is more compatible with wafer-scale fabrication processes. First, we report the fabrication of large arrays of FETs based on graphene ribbons with controlled electrical properties. These arrays were built from high-quality large area graphene synthesized by chemical vapor deposition (CVD), followed by patterning steps using photolithography and plasma etching processes. Then, we report the design of two different architectures for single-molecule experiments: nanoconstrictions and nanogaps. Nanoconstrictions were achieved using electron-beam lithography (EBL), allowing to pattern high-resolution features (50nm) in the graphene channel. Nanogaps were obtained using the electroburning technique to open a gap of a few nanometers in the graphene channel6. We will present the design and fabrication process of these architectures, as well as their characterization using high-resolution microscopy (SEM/AFM) and transport measurements. Finally, we will discuss approached for the single-molecule functionalization for these architectures and their application in conductance-based single-molecule measurements.

An Experimental Study on Mixed-Dimensional 1D-2D van der Waals Single-Walled Carbon Nanotube-WSe2 Hetero-Junction

This experimental study investigates a novel multi-functional one dimensional-two dimensional (1D-2D) heterojunction made of two different band-gap semiconductors, i.e. single-walled carbon nanotube (SWCNT) and tungsten di-selenide (WSe2). The proposed ultra-scaled van der Waals junction behaves like a ${p}$ -type field-effect transistor (FET) or a gated ${p}$ - ${n}$ diode, depending upon the gate bias. A detailed physical study of charge transportation mechanism is presented in a wide range of applied potentials. The obtained results are important towards scaling nanoelectronics to atomic thicknesses by means of the 1D-2D hybrid junctions with additional multi-functional solid-state devices.

Surface inversion layer effective minority carrier mobility as one of the measures of surface quality of the p-aSi:H/i-aSi:H/cSi heterojunction solar cell

The lateral transport of minority carriers in the surface inversion layer of a crystalline silicon (cSi) surface for a p-aSi:H/i-aSi:H/cSi heterojunction (SHJ) solar cell was experimentally analyzed to study defects/traps at the aSi:H/cSi interface and/or on the cSi surface. To extract the lateral surface inversion layer current, a field-effect transistor type test element group device was designed and fabricated on a cSi wafer where SHJ cells were co-integrated. By analyzing the lateral surface inversion layer current, the effective surface minority carrier mobility was calculated. The extracted mobility was one order of magnitude smaller than that of a reference MoOx/i-aSi:H/cSi structure but it increased by low-temperature post-deposition annealing with respect to the reference. This method is highly sensitive to the quality of the aSi:H/cSi interface and/or the cSi surface. The density of trap sites was estimated to be of the order of 1011 cm−2 at the aSi:H/cSi interface and/or on the cSi surface.

Construction of Two-Dimensional Regression Models of the Current-voltage Characteristics of the Output Current of Field-Effect Transistors Using the PLExp Information System

A problem was formulated and a methodology proposed for constructing the two-dimensional current-voltage characteristic of an output current of a field transistor in the form of its dependence on the input and output voltages. With the aid of the PLExp information system, the design of the computational test was fulfilled and the results of field studies were processed in studying the characteristics of the output current of field transistors with a controlling p–n transition. A two-dimensional regression analysis of the dispersion of the experimental data was conducted, the quality of the regression models that were constructed was evaluated, and the effect on the quality of the regression model from the number of input test points was studied. A regression model using the orthogonal central second-order composition plot was developed. The results of computational test on field studies are provided in the form of the table of coefficients of the polynomials for the two-dimensional regression models and in the form of graphs. In order to construct the current-voltage characteristics, polynomial two-dimensional regression models constructed on nine observational points were used. The ranges of factor variation within which the regression model is significant were established. The significance of the regression equation as a whole was evaluated using two criteria: the Fisher criterion and the criterion of the mean error of approximation. It was discovered that decreasing the number of test points by a factor of three does not result in significant quality degradation of the regression model. The proposed experimental method based on the regression model makes it possible to construct the two-dimensional characteristics also of other types of insulated-gate field effect transistors.

Thermoelectric converter based on metal-dielectric-semiconductor-metal structures for cooling processors

A thermoelectric transducer based on MDSM structures of the field-effect transistor (FET) type is proposed, in which the thermal energy of the environment is converted into electrical energy. We use a new principle of converting thermal energy into electrical energy. We show that with the help of such a converter, it is possible to dramatically increase the efficiency of processors due to the heat generated by the processor is converted by this converter again into electricity that transfers to the processor.

Anisotropic In‐Plane Ballistic Transport in Monolayer Black Arsenic‐Phosphorus FETs

AbstractThe performance limits of monolayer arsenic‐phosphorus (AsP) field‐effect transistors (FETs) are explored by first‐principles simulations of ballistic transport in nanoscale devices. The monolayer AsP holds a direct bandgap of 0.92 eV with significantly anisotropic electronic properties. Transfer characteristics of n‐type and p‐type AsP FETs are thoroughly investigated by scaling channel length in the armchair and zigzag direction, respectively. The simulation results indicate that AsP FETs exhibit exceptional device characteristics, such as high on‐state current, short delay time, and low power consumption. Moreover, transfer characteristics demonstrate superior anisotropy on in‐plane electrical transport properties. In particular, in the zigzag direction, even if the channel length is scaled down to 4 nm, the device performance still can satisfy the International Technology Roadmap for Semiconductors high‐performance requirement. Finally, through benchmarking energy‐delay product against other typical 2D FETs, AsP FETs are revealed to be strongly competitive 2D FETs.

Robotic Prototyping of Paper-Based Field-Effect Transistors with Rolled-Up Semiconductor Microtubes

In this article, we propose a robotic rapid prototyping technology for fabricating a new type of paper-based field-effect transistors (FETs). Unlike the existing paper-based electronics developed primarily based on the printing of conductive and semiconductive inks on paper substrates, this new prototyping technology integrates single rolled-up semiconductive microtubes into a device with robotically printed electrodes as the semiconductive channel, through robotic micromanipulation techniques. To improve the uniformity of the printed silver (Ag) ink electrodes, we designed a time-shift mechanism to compensate for the nonuniform ink dispersion at the beginning and ending phases of the robotic printing process. In addition, image processing and motion control algorithms were developed to enable automatic transfer of the prefabricated microtube from its hosting silicon wafer to the printed electrodes on a paper substrate. The effectiveness of the proposed technology was verified by fabricating the paper-based FETs with semiconductive zinc oxide (ZnO) microtubes. Preliminary tests on the mobility of the fabricated ZnO FET demonstrated improved performance over the conventional paper-based FETs with printed semiconductive channels.