Gate Field Effect Transistor Research Articles

Impacts of Cavity Thickness and Insulating Material on Dielectric Modulated Trench Junction-less Double Gate Field Effect Transistor for Biosensing Applications

Introduction: This work represents the influence of gate dielectric, and the nano-cavity gap of a dielectric modulated trench gate Junction-less Double Gate Field Effect Transistor (JL-DGFET) on the different performance indicators is investigated considering the Low-Frequency Noise. Methods: It is noted that the gate dielectric and the nanogap, both parameters, have a substantial influence on the sensing capacity and performance of noise of the device. Results: A double gate suitable dielectric material and cavity thickness can effectively improve the biosensor’s sensitivity with a minimum amount of noise. Conclusion: The sensitivity is found to increase up to 9.5 for dielectric constant, k = 3.57 and 6.5 for dielectric constant, k = 2.1.

Label-Free Electrochemical Sensor Sensitivity Enhancement Using Field Effect Transistors: Fluoride Ions for Fuel Cell Degradation Analysis

In the context of proton exchange membrane fuel cells, precise monitoring of fluoride ions in the effluent water is crucial. Associated with the fluoride ion accumulation, membrane degradation and reduction of fuel cell efficiency arise. This study focuses on developing extended gate field-effect transistors (EGFET) sensors for real-time monitoring of fluoride ion concentrations. High sensitivity and specificity in detecting the concentration of fluoride ions using both N-type (TN0702) and P-type (LP0701) metal-oxide-semiconductor field-effect transistors (MOSFET) were achieved. The transfer characteristics (Id vs Vgs) owere thoroughly examined across a range of fluoride concentrations from parts per million (ppm) to parts per billion (ppb). N-type MOSFET-based sensors showed a distinct decrease in drain current (Id) with increasing fluoride concentration. With fluoride concentrations changed, the P-type MOSFET exhibited a notable shift in the threshold voltage (Vgs). A robust linear relationship was observed on calibration curves with R2 values exceeding 0.90 between the natural logarithm of fluoride concentration (lnC) and gate-source voltage (Vgs). This work demonstrates that MOSFET can significantly enhance the sensitivity of electrochemical sensors without complex labeling processes. The improvement has a future in the miniaturization of cost-effective sensor systems for fuel cell applications, facilitating real-time performance and degradation monitoring.

Multi-Electrode Extended Gate Field Effect Transistors Based on Laser-Induced Graphene for the Detection of Vitamin C and SARS-CoV-2.

Despite the clinical data showing the importance of ascorbic acid (AA or vitamin C) in managing viral respiratory infections, biosensors for their simultaneous detection are lacking. To address this need, we developed a portable and wireless device for simultaneous detection of AA and SARS-CoV-2 virus by integrating commercial transistors with printed laser-induced graphene (LIG) as the extended gate. We studied the effect of laser printing pass number and showed that with two laser printing passes (2-pass LIG), the sensor sensitivity and limit of detection (LOD) for AA improved by a factor of 1.6 and 12.8, respectively. Using complementary characterization methods, we attribute the improved response to a balanced interplay of crystallinity, defect density, surface area, surface roughness, pore density and diameter, and mechanical integrity/stability. These factors enhance analyte transport, reduce noise/variability, and ensure consistent sensor performance, making 2-pass LIG the most effective material in this work. Our sensors exhibit promising performance for detecting AA with a selective response in the presence of common salivary interfering molecules, with sensitivity and LOD of 73.67 mV/dec and 54.04 nM in 1× phosphate buffered saline and 81.05 mV/dec and 78.34 nM in artificial saliva, respectively. We also showed that functionalization of the 2-pass LIG gate with S-protein antibody enables the detection of SARS-CoV-2 protein antigens with an ultralow LOD of 52 zg/mL─an improvement of more than 10-fold compared to 1-pass LIG─and 4 particles/mL for virion mimics with a selective response against influenza virus and multiple human coronavirus strains. With low signal drift/hysteresis and wireless capabilities, the developed device holds great potential for improving at-home monitoring and clinical decision-making.

Vanadium oxide thin films growth by a chemical solution deposition method and its pH sensor toward bio-sensing devices

Abstract We report on the evaluation of the structure of VOx thin films under different fabrication conditions of the chemical solution deposition method and the pH response of an extended gate field effect transistor (EGFET)-type pH sensor. Polycrystalline V2O5 thin films of 30 and 60 nm thick and amorphous VOx thin films of about 30 nm thick were successfully prepared under different precursor solution conditions. Using polycrystalline V2O5 thin films and amorphous VOx thin films as an extended gate (EG) electrode, protypes of EGFET-type pH sensors were fabricated and investigated their pH response characteristics. The average pH responsibility of 64 mV/pH, which exceeded the theoretical Nernst limit, was observed over a wide pH range from 2.4 to 8.0 in the amorphous VOx extended gate sensor. It was also found that stable pH response measurements could be performed on amorphous VOx film samples.

Brewer's Spent Grain-Cellulose-Coated Copper Electrode-Based Extended Gate Field-Effect Transistor for Nonenzymatic Glucose Detection toward Diagnosis of Diabetes Mellitus.

The demand for environmentally friendly, reliable, and cost-effective electrodes for glucose sensor technology has become a major research area in the paradigm shift toward green electronics. In this regard, cellulose has emerged as a promising flexible biopolymer solution with unique properties such as biocompatibility, biodegradability, nontoxicity, renewability, and sustainability. Because of their large surface area and porous structure, fibrous cellulose substrates quickly adsorb and disperse analytes at detection sites. This work focuses on utilizing glyoxal-treated cellulose (derived from brewer's spent grain (BSG)) for the fabrication of extended gate field-effect transistor (EGFET)-based glucose sensors. This investigation extends to the utilization of BSG-cellulose for glucose detection in biomimicking electrolytes (phosphate buffer saline) to facilitate glucose detection in human blood samples. The fabricated electrode demonstrates a linear range of glucose detection from 1 to 13.5 mM with a Langmuir adsorption coefficient (K) of 0.102. Also, its selectivity toward glucose over interfering molecules such as sucrose, fructose, ascorbic acid, and uric acid under physiological conditions has been demonstrated. This cellulose-based EGFET electrode exhibits a sensitivity of 6.5 μA mM-1 cm-2 with a limit of detection (LOD) of 0.135 mM. Computational studies by density functional theory calculations confirmed the higher binding affinity of glucose molecules with glyoxal-modified cellulose (-0.95 eV) than with pristine cellulose (-0.46 eV). Here, the novelty lies in the fabrication of electrodes with biodegradable catalysts and their integration into the EGFET configuration.

C60 Functionalized Single‐Walled Carbon Nanotube‐based Phototransistor for Efficient Detection of Visible Light Under Appropriate Gate Electrostatics

AbstractThe current study concerns highly reliable visible light sensing by C60 fullerene functionalized single‐walled carbon nanotube (SWCNT) based phototransistor. The absorbance of visible light (532 nm) increases significantly due to the formation of an interlink between the SWCNT network and C60 clusters. Photogenerated excess electrons in SWCNT are trapped by the C60 clusters and increase the effective hole concentrations in the SWCNT channel, which eventually improves the photoconductive gain. C60‐SWCNT channel is further integrated into the back gated field effect transistor (FET) structure in which 90 nm SiO2 dielectric thickness is used. The responsivity toward visible light is further enlarged with appropriate negative gate electrostatic. In order to ensure the morphological and structural behavior of C60‐SWCNT, various microscopic and spectroscopic characterizations are performed. The C60‐SWCNT phototransistor exhibits responsivity of 1.219 A W−1 at Vgs = – 21 V. The detectivity and rise/fall time of C60‐SWCNT came around to be 2.34 × 1010 Jones, 86.42 ms/3.35 ms at the same Vgs. The maximum external quantum efficiency (EQE) of the C60‐SWCNT phototransistor is very high, ≈274%. In the overall study, a comprehensive discussion is introduced on the effect of variable gate potential on the performance of the C60‐SWCNT phototransistor.

Oxygen-assisted recoverable hydrogen sensor based on sensing gate field effect transistor with ppb-level detection ability

Oxygen-assisted recoverable hydrogen sensor based on sensing gate field effect transistor with ppb-level detection ability

Green and solid state reduction of GO monolayers sandwiched between Arachidic acid LB layers

A novel, single step and environment friendly solid state approach for reduction of graphene oxide (GO) monolayers has been demonstrated, in which, arachidic acid/GO/arachidic acid (AA/GO/AA) sandwich structure obtained by Langmuir-Blodgett (LB) technique was heat treated at moderate temperatures to obtain RGO sheets. Heat treatment of AA/GO/AA sandwich structure at 200 °C results in substantial reduction of GO, with concurrent removal of AA molecules. Such developed RGO sheets possess sp2-C content of ∼69 %, O/C ratio of ∼0.17 and significantly reduced I(D)/I(G) ratio of ∼1.1. Ultraviolet photoelectron spectroscopy (UPS) studies on RGO sheets evidenced significant increase in density of states in immediate vicinity of Fermi level and decrease in work function after reduction. Bottom gated field effect transistors fabricated with isolated RGO sheets displayed charge neutrality point at a positive gate voltage, indicating p-type nature, consistent with UPS and electrostatic force microscopy (EFM) measurement results. The RGO sheets obtained by heat treatment of AA/GO/AA sandwich structure exhibited conductivity in the range of 2–7 S/cm and field effect mobility of 0.03–2 cm2/Vs, which are comparable with values reported for RGO sheets obtained by various chemical/thermal reduction procedures. The extent of GO reduction is determined primarily by proximity of AA molecules and found to be unaltered with either escalation of heat treatment temperature or increase of AA content in sandwich structure. The single-step GO reduction approach demonstrated in this work is an effective way for development of RGO monolayers with high structural quality towards graphene-based electronic device applications.

Developing Field Effect Transistor Sensors Based on DNA Probes to Detect Staphylococcus Lugdunensis Bacteria

The goal of this research is to work with an Electrical Double Layer (EDL)-gated Field Effect Transistor (FET) to detect the bacteria Staphylococcus lugdunensis, which can cause a variety of illnesses, including infections of the skin and soft tissues. In rare cases, Staphylococcus lugdunensis can be successfully identified using the combination of a positive catalase test, a negative tube coagulase test, a positive PYR test, and a positive ornithine decarboxylase test. We are employing an Electrical DoubleLayer (EDL)-gated Field Effect Transistor (FET) to speed up the procedure because this test is time consuming and requires a highly competent individual to perform. An ssDNA probe was developed, and effectively immobilized on a gold surface electrode sensor with a square surface, and due to hybridization with the cDNA at different concentrations, electrical signals were generated in the form of current.Our sensor was fabricated using photolithography where the gold electrode surface having 500 μm x 500 μm gate sensing area consisting of each individually addressable sensor arranged in a 1 x 8 array which is the extent gate was expose for immobilization purpose. The sensor was then subjectedto O2 plasma & HCl solution for surface cleaning and fluorescence image of baregold were taken Figure1(b).The Single-Stranded DNA comprising of fluorescent dye (FAM) at 3’ and thiol modifier at 5’ was drop-casted on the gold surface and was incubated for 24 hours at 24°C. After, it went through a washing process in order to remove the unbound ssDNA and fluorescence images were taken. We observed that intensity was higher than that of baregold which indicates that our probe has successfully immobilized on the gold surface Figure 1(b).Figure 1(a) represents the device that we designed. The system works with N-Channel Enhancement-Mode DMOS FET (VN10LP) in which a continuous drain voltage (3.5 V) was applied and the drain current which is the signal, were measured at two distinct gate bias voltage (2V and 3V). cDNA having quencher (BHQ1) at 5’ was diluted in different concentration namely 1fM, 10fM, 100fM and 1000fM. These cDNA with different concentrations were drop-casted on our sensor with Tris-EDTA (TE) buffer as the baseline and starting with lower concentration to higher concentration every after 12 seconds periodically where we record the change in signal as shown in Figure 1(c).After the electrical measurement, fluorescence image was taken and we can observe that it quenched which indicates that the cDNA and the immobilized ssDNA has successfully hybridized which give the signal change. Figure 1: (a) Surface Immobilization Principal Display in Extended Gate EDL BioFETs. (b)Fluorescence value comparison. (c) Plot showing the change in drain current over time for aptamersensors exposed to various cDNA concentrations. Figure 1

Detection of Thiocholine for Pesticide Qualification Using Indium-Tin-Oxide-Coated Vertically Aligned Silicon Nanowires Extended Gate Field-Effect Transistor

Thiocholine is the hydrolysis of acetylthiocholine (ATCh) by acetylcholinesterase (AChE). The detection of thiocholine can be utilized to assess the activity and inhibitors of AChE, making it a valuable recognition element for constructing biosensors used in pesticide detection[1, 2]. The enzymatic hydrolysis of ATCh is catalyzed by AChE. First, high-aspect-ratio vertically aligned silicon nanowires (VASiNWs) were successfully fabricated through metal-assisted chemical etching (MACE). To investigate the impact of nanostructures on enhancing the sensitivity of the extended gate of the field-effect transistor (EGFET), the gate terminal was connected to 3-mercaptopropyl trimethoxysilane (MPTMS) modified indium-tin-oxide (ITO)-coated VASiNWs for the electrical detection of ATCh-catalyzed thiocholine, as illustrated in Figure 1. Various solutions of ATCh-catalyzed thiocholine were collected by applying different concentrations of ATCh (ranging from 2 mM to 10 mM) to the AChE-coated wells independently for 10 minutes. Subsequently, these solutions were introduced to the MPTMS modified ITO-coated VASiNWs EGFET, and the change in drain current was measured using a semiconductor parameter analyzer (HP 4145B). The thiocholine current demonstrated a sensitivity of 29.39 uA/concentration and a linearity of 0.88. Exploring the potential of pesticides to inhibit AChE hydrolysis represents a significant breakthrough, paving the way for the advancement of biosensors in pesticide detection. References Liu, G., et al., Sensitive electrochemical detection of enzymatically generated thiocholine at carbon nanotube modified glassy carbon electrode. Electrochemistry Communications, 2005. 7(11): p. 1163-1169. Pandey, P.C., et al., Acetylthiocholine/acetylcholine and thiocholine/choline electrochemical biosensors/sensors based on an organically modified sol–gel glass enzyme reactor and graphite paste electrode. Sensors and Actuators B: Chemical, 2000. 62(2): p. 109-116. Figure 1

Effects of hydrostatic pressure, temperature, and position-dependent mass on the nonlinear optical properties of triple delta-doped GaAs quantum well

In this study, we thoroughly investigate the impacts of hydrostatic pressure, temperature, and position-dependent mass (PDM) on the nonlinear optical properties of asymmetric triple δ-doped GaAs quantum wells. Our analysis covers total optical absorption coefficients, relative refractive index changes, nonlinear optical rectification, second harmonic generation, and third harmonic generation. Initially, we employ PDM to solve the time-independent Schrödinger equation using the diagonalization method under effective mass and parabolic band approaches, considering pressure and temperature dependencies. Utilizing the first four energy eigenvalues and eigenfunctions, we apply the compact density matrix method to compute the system’s nonlinear optical properties numerically. The results indicate a shift in optical property peak positions toward lower (higher) energy spectra with increasing hydrostatic pressure (temperature). Furthermore, the influence of PDM shifts the system’s optical properties toward the higher energy spectrum, resembling the effect of temperature. From an experimental and theoretical perspective, one of the topics that researchers work on most is GaAs-based δ-doped systems (δ-doped heterojunction bipolar transistors, δ-doped field effect transistors, δ-multiple independent gate field effect transistors, etc.). We believe these findings will provide valuable insights for the researchers involved in GaAs-based δ-doped optoelectronic device design.

Fabrication and Characterization of Four-State Inverter Utilizing Quantum Dot Gate Field-Effect Transistors (QDGFETS)

This paper presents the experimental results of nMOS quantum dot gate field-effect transistor (QDG-FET) based four-state inverter fabricated and tested with Si/SiO2 and Ge/GeO2 quantum dots. The site-specific self-assembly of SiOx-cladded Si and GeOx-cladded Ge quantum dot layers in the gate region implements both the driver and load FETs in enhancement nMOS inverters. A four-state inverter will allow the reduction of FET count in logic block in microprocessors.

Lignin Hydrogels as a Use Case for a New Miniaturized Chemical Sensing Platform Based on Suspended Gate Field Effect Transistors

Lignin Hydrogels as a Use Case for a New Miniaturized Chemical Sensing Platform Based on Suspended Gate Field Effect Transistors

Flexible and Disposable Hafnium Nitride Extended Gates Fabricated by Low-Temperature High-Power Impulse Magnetron Sputtering.

To obtain a high-performance extended gate field-effect transistor for pH detection, hafnium nitride (HfN) was first fabricated on an indium tin oxide on polyethylene terephthalate (ITO/PET) substrate using a high-power impulse magnetron sputter system (HiPIMS) in this study. It can be easily applied in biomedical diagnostic and environmental monitoring applications with the advantages of flexible, disposable, cost-effective, and reliable components. Various duty cycle conditions in HiPIMSs were designed to investigate the corresponding sensing performance and material properties including surface morphology and composition. As the duty cycle increased, the grain size of HfN increased. Additionally, X-ray photoelectron spectroscopy (XPS) analysis illustrated the presence of HfOxNy on the deposited HfN surface. Both behaviors could result in a better pH sensing performance based on the theory of the site-binding model. Subsequently, HfN with a 15% duty cycle exhibited excellent pH sensitivity and linearity, with values of 59.3 mV/pH and 99.8%, respectively; its hysteresis width and drift coefficient were -1 mV and 0.5 mV/h, respectively. Furthermore, this pH-sensing performance remained stable even after 2000 repeated bending cycles. These results indicate the potential and feasibility of this HiPIMS-deposited HfN for future wearable chemical applications.

P/N-Type Conversion of 2D MoTe2 Controlled by Top Gate Engineering for Logic Circuits.

Two-dimensional (2D) transition-metal dichalcogenides (TMDCs) are regarded as promising materials for next-generation logic circuits. Top gate field-effect transistors (FETs) have independent gate control ability and can be fabricated directly on TMDC materials without a transfer process. Therefore, it has the merits of device reliability and complementary metal-oxide semiconductor (CMOS) process compatibility, which are demanded in practical circuit-level integration. However, the fabrication of the top gate FET involves depositing an insulating dielectric layer and a gate electrode in sequence on the TMDC channel material, which may affect the device performance. Insightfully investigating the influences of different top-gate-deposition methods on the electrical properties of the TMDC channel and further harnessing these influences to realize a homogeneous CMOS device on an identical 2D TMDC platform are with practice significance. In this work, p/n-type controllable top gate FET arrays based on 2H-MoTe2 are fabricated by using different top-gate-deposition methods. The electron-beam evaporation (EBE) of top metal gate exhibits an obvious n-doping effect on the 2H-MoTe2 channel and converts it from p-type to n-type, whereas the thermal evaporation of top gate affects little to the channel. High-resolution transmission electron microscopy (HR-TEM) analysis reveals that the high-energy metal atoms from the EBE process can penetrate through the 30 nm gate dielectric layers (including 10 nm Al2O3 seeding layer), leading to multiple atomic defects in both MoTe2 and the interface between MoTe2 and Al2O3. Furthermore, by utilizing the top gate engineering, a large-scale double-top-gate MoTe2 homogeneous CMOS inverter array is fabricated. The CMOS inverters exhibit clear logic swing, negligible hysteresis, and high device yield (∼93%), indicating high device reliability and stability. Notably, the fabrication process is facile, free from transfer procedure, and compatible with traditional silicon technology. This work promotes the application of 2D TMDCs in nanoelectronics integration.

Copper Recovery from Mobile Phone Printed Circuit Board E-Waste and Transforming into CuO@C for Electrode Material in Extended Gate Field-Effect Transistors Facilitating Non-Enzymatic Ascorbic Acid Detection

Copper Recovery from Mobile Phone Printed Circuit Board E-Waste and Transforming into CuO@C for Electrode Material in Extended Gate Field-Effect Transistors Facilitating Non-Enzymatic Ascorbic Acid Detection

High-Performance Ammonia Gas Sensor Based on a Catalytic Ruthenium- Gated Field-Effect Transistor

High-Performance Ammonia Gas Sensor Based on a Catalytic Ruthenium- Gated Field-Effect Transistor

Capacitance modeling, simulation and RF characterization of horizontal floating gate field effect transistor (H-FGFET) for gas sensing application

In this paper, physics-based capacitance model has been developed for horizontal floating gate field effect transistor (H-FGFET). The horizontal design of floating gate (FG) FET allows detection of large gas molecules like nitrogen dioxide (NO2), sulphur dioxide (SO2), hydrogen sulfide (H2S), carbon dioxide (CO2) etc. In order to validate the proposed model, the device has been designed using Sentaurus TCAD simulator and results have been validated with experimental data. Different electrical parameters such as transfer characteristics, switching ratio, output characteristics, threshold voltage, drain induced barrier lowering (DIBL), C-V characteristics, transconductance, output conductance and RF characteristics of the device have been analyzed at room temperature. The simulation result shows that increase in channel length of H-FGFET results in decreased leakage current, improved switching performance, increased gate capacitance and reduced DIBL. The comparative analysis of H-FGFET with previously reported floating gate FET structures reveal that proposed device offers highest switching ratio. The RF characteristics of H-FGFET illustrates that proposed device can operate efficiently as an amplifier for the frequency range of 0.1 GHz to 100 GHz. Further, the proposed device has also been tested for the detection of nitrogen dioxide gas and results reveal that with increase in operating temperature from 30 °C to 180 °C the leakage current of the device increases from 10−13 to 10−9 and OFF current sensitivity of the proposed sensor changes by 82% on changing the work function of sensing layer from 50 meV to 250 meV.

High pH stability and detection of α-synuclein using an EGFET biosensor with an HfO2 gate deposited by high-power pulsed magnetron sputtering

In this research, hafnium oxide (HfO2) was first fabricated in an in-house-developed high-power pulsed magnetron sputtering system (HiPIMS) functionalized for application as a high-performance extended gate field-effect transistor (EGFET) for the detection of pH and proteins associated with Parkinson's disease (PD). PD is the second most common neurodegenerative disease in elderly people after Alzheimer's disease. The α-synuclein protein in patients’ blood may be a potential biomarker in the early stage of PD. Detection of α-synuclein with high sensitivity and nonspecific binding through HfO2-EGFET biosensors has the advantages of low cost and simple fabrication from disposable EGs. Among the duty cycle conditions tested, HfO2 deposited at a 25% duty cycle in HiPIMS exhibited superior pH sensitivity and linearity, with values of 56.4 mV/pH and 99.7%, respectively. The hysteresis width and drift coefficient are −3 mV and 0.3 mV/h, respectively. To overcome the Debye length limitation, 100-fold diluted phosphate buffer solution and the PMOS configuration were used to determine the α-synuclein for which the isoelectric point was 4.67. The negative gate bias in the PMOS configuration successfully causes α-synuclein to approach the surface of HfO2 EG to achieve a sensitivity of 12.1 mV/dec and a linearity of 99.5% in the range of 0.1–1000 pg/mL. The limit of detection is 0.198 pg/mL, and the immobilized surface ultimately binds specifically, resulting in low interference signals from other related biomarkers. This promising study shows that detecting various proteins involved in different diseases and performing clinical tests can be accomplished in the future.

Towards monitoring of critical illness via the detection of histones with extended gate field-effect transistor sensors

Extracellular histone proteins in the blood indicate a heightened risk of morbidity after trauma or in major illnesses such as sepsis. We present the development of an aptasensor for histone detection with an extended gate field-effect transistor (EGFET) configuration, which benefits from low power consumption, rapid response, and compatibility with miniaturized gold electrodes. Histones have a high isoelectric point and charge density, which cause them to physically adsorb to non-specific elements of the sensor that have available electrostatic charges. To combat this, the sensing surface is formed with a thiol-modified, high-affinity and histone-specific RNA aptamer sequence and by co-immobilizing with poly(ethylene glycol) methyl ether thiol (PEG) as a blocking agent. Surface plasmon resonance (SPR) is used to analyze aptamer and PEG immobilization strategies, confirm histone binding, and calculate kinetic binding constants. Through comparison of different blocking agents and time-dependent preparation, the ideal equilibrium dissociation constant (KD) is estimated to be below 200 pM, which is the upper range of extracellular histone concentrations in critically ill patients with high mortality. The EGFET sensitivity of the optimized aptasensor is 6.65 mV/decade concentration change for histone H4 with a physiologically relevant 5 pM limit of detection. Selectivity tests with 100 nM bovine serum albumin (BSA) demonstrate a signal response that is 13-fold smaller than for histones. This EGFET aptasensor platform is suitable for future point-of-care monitoring of histone levels in critically ill patients, thus permitting the early detection of increased risk and the need for more aggressive interventional measures to prevent mortality.