In this paper, a junction-free charge plasma tunnel field-effect transistor (JF-CP-TFET) is proposed and analyzed for the first time to sense hydrogen (H2) gas. Using junction-free and charge-plasma approaches, the proposed JF-CP-TFET-based sensor minimizes random dopant fluctuations, a large thermal budget requirement, and complex processes in the semiconductor sensor production process. The sensing performance of the JF-CP-TFET-based gas sensor is demonstrated by analyzing changes in the work function of the gate of palladium (Pd) catalytic metals, which are proportional to the pressure of H2 gas exposed at the metal gate surface. The presence of H2 gas has been demonstrated by variations of the DC/AC parameters of the proposed sensor, such as carrier concentration, energy band, electric field, transfer characteristics, threshold voltage (VTh), and subthreshold swing (SS). The sensitivity of the JF-CP-TFET-based sensor has been eValuated in terms of drain current (IDS), ION/IOFF ratio, VTh, and SS change in the presence and absence of H2 gas molecules. The sensing capabilities of the proposed JF-CP-TFET-based gas sensor demonstrate that it could potentially be employed for H2 gas detection with excellent sensitivity and reliability.

This paper introduces a novel GaAs/GaSb polarity-controlled tunnel field-effect transistor (GaAs/GaSb PC-TFET)-based biosensor with high sensitivity for label-free biomolecule detection. The polarity-controlled concept is employed to create the drain/source region in the proposed structure, reducing fabrication complexity and cost. The electrical characteristics (drain current and threshold voltage) of the GaAs/GaSb PC-TFET biosensor change as different biomolecules are immobilized in the nano-cavity region. This study thoroughly investigates the ON-current sensitivity (S _I_ON ) and threshold voltage sensitivity (S _V_Th ) parameters of the proposed GaAs/GaSb PC-TFET biosensor. Findings indicate that the GaAs/GaSb PC-TFET biosensor exhibits higher S _I_ON and S _V_Th values ( 1.53× 10^14 and 0.79) as compared to recently reported similar FET/TFET-based biosensors. The efficiency of the proposed biosensor is further examined by studying the impact of the molecule’s charge density, non-ideality (steric hindrance and different fill factors), variation in cavity dimensions, temperature shifts, and noise on sensitivity. Additionally, selectivity, linearity, and transient response are analyzed to validate the proposed GaAs/GaSb PC-TFET biosensor’s abilities. The assessment of all investigated results reveals that the proposed GaAs/GaSb PC-TFET biosensor is a promising candidate for biosensing applications.

The Severe Acute Respiratory Syndrome Co-ronavirus 2 (SARS-CoV-2) epidemic has raised significant public health concerns due to its rapid global spread. Currently, there are no effective treatments or vaccines available for SARS-CoV-2, making early detection essential for controlling outbreaks and reducing casualty rates. This study presents a feasibility assessment of a GaAs/Ge Polarity Controlled Tunnel Field-Effect Transistor (GaAs/Ge PC-TFET)-based biosensor designed for the rapid detection of SARS-CoV-2. The proposed GaAs/Ge PC-TFET biosensor detects SARS-CoV-2 in clinical samples by determining the equivalent dielectric constants (k) of the SARS-CoV-2 spike protein (S-protein) and DNA. The sensor’s electrical properties change significantly when SARS-CoV-2 is immobilized within its nano-cavity region. The sensitivity of the GaAs/Ge PC-TFET biosensor is evaluated in terms of drain current (IDS), threshold voltage (VTh), subthreshold slope (SS), and the ON/OFF-current (ION/IOFF) ratio, with respect to the k-value and charge density ( ρ ) of the SARS-CoV-2 virus. Additionally, this study analyzes the biosensor’s performance considering non-ideal immobilization issues, thermal drift, and environmental noise. Technology Computer-Aided Design (TCAD) software was employed for the implementation and simulation of the proposed GaAs/Ge PC-TFET biosensor. Ultimately, the proposed GaAs/Ge PC-TFET biosensor holds promise as a diagnostic device for the quick and accurate detection of SARS-CoV-2 from patient saliva samples.

This paper proposes a novel polarity-control junctionless tunnel field-effect transistor (PC-JL-TFET)-based biosensor for the label-free detection of biomolecule species in efficient ways. Unlike conventional designs, the polarity-control concept induces the generation of drain (n(+)) and source (p(+)) regions inside the proposed structure when a bias of (-/+) 1.2V is applied at the polarity gates-1/2 (PG-1/2), to form a conventional TFET. To capture the biomolecules, a nano-cavity is created within the source region's dielectric oxide toward the tunneling interface. The presence of biomolecules is electronically detected based on either solely the dielectric constant (neutral biomolecules) or the combination of charge density and dielectric constant (charged biomolecules). The proposed device can perform label-free recognition of biomolecules such as Uricase, Keratin, Biotin, Streptavidin and so on. To investigate the sensing performance of the proposed biosensor, significant biosensing metrics such as the electric field, energy band diagram, tunneling current, subthreshold slope, I-ON/I-OFF ratio and threshold voltage have been studied. The proposed PC-JL-TFET biosensor achieves a maximum sensitivity of 5.31 x 10(10) for neutral biomolecules with a dielectric constant of 12 and 1.11 x 10(10) for negatively charged biomolecules (-1 x 10(12)C/cm(2)) with a dielectric constant of 8. The proposed biosensor's selectivity, linearity and temperature-based analysis have also been evaluated for different biomolecules. Additionally, real-time practical scenarios, such as partially filled nano-cavities and the random position of biomolecules in the nano-cavity-based analysis, have also been incorporated.

To reduce the fabrication complexity and cost of nanoscale biosensors, a novel electrically doped concept is proposed for the first time, aiming to implement a dielectric-modulated junctionless tunnel field-effect transistor (DM-ED-JLTFET) for label-free biomolecule detection. The n+ drain and p+ source regions in the proposed device are induced by applying a bias of polarity gate-1 (PG-1) = +1.2 V and PG-2 = -1.2 V, respectively, over the ultrathin silicon body. A nanogap cavity beneath the PG-2 terminal is formed by etching a part of the dielectric oxide layer toward the tunneling interface to capture the biomolecule test sample. The existence of neutral and charged molecules in the cavities has been investigated using changes in the electrical characteristics of the proposed biosensor, such as drain current, energy band, and electric field. The sensing performance of the proposed biosensor is evaluated in terms of drain current (I-DS), subthreshold swing (SS), threshold voltage ( V-Th ), switching ratio (I-ON/I-OFF), and transconductance-to-current ratio ( g(m)/I-DS). The proposed DM-ED-JLTFET biosensor achieves a maximum sensitivity of {5.58} x 10(10) with a fully filled nanogap for a neutral biomolecule with a dielectric constant of 12. The effects of non-ideal issues on sensitivity, such as different fill factors (FFs) and steric hindrances, are also studied of the proposed biosensor to understand the practical challenges.

In this paper, a Si/GaSb-polarity control tunnel field effect transistor (Si/GaSb-PC-TFET) is proposed as a label-free biosensor. To enhance the sensing performance of the proposed biosensor, a narrow band-gap heteromaterial named GaSb is employed in the source region. The dielectric constant $(k)$ and charge density ($\mathrm{N}_{\text {bio }}$) of various biomolecules are utilized for assessing their presence via the proposed Si/GaSb-PC-TFET-based biosensor. In the proposed work, we considered the biomolecules with dielectric constants $(k)$ from 1 to 12 and charge densities ranging from $\pm 1 \times 10^{10} \mathrm{C.cm}^{-2}$ to $\pm 1 \times 10^{12} \mathrm{C.cm}^{-2}$ with a fixed k-value. The sensing efficiency of the proposed biosensor has been determined in terms of drain current ($\mathrm{I}_{\mathrm{DS}}$), and the maximum $\mathrm {I_{D S}}$ sensitivity is obtained as $1.11 \times 10^{13}$ for neutra $(k=12)$ and $1.28 \times 10^{13}$ for negatively charged $(N_{\text {bio }}=-1 \times 10^{12}$ C. $\mathrm{cm}^{-2}, k=12$) biomolecules. Furthermore, the sensitivity of the proposed Si/GASb-PC-TFET biosensor has also been investigated by employing different partially filled nano-cavities.

In this paper, a dielectric modulated polarity control tunnel field-effect transistor (DM-PC-TFET)- based biosensor has been proposed for the first time for breast cancer cells (BCCs) detection. The detection method is based on the significant difference in dielectric constant between cancerous and healthy breast cell lines in the microwave frequency band.When BCCs with different dielectric constants are filled in the sensing region of the proposed DM-PC-TFET-based biosensor, the electrical characteristics of the device vary, allowing for early-stage breast cancer detection. The sensing ability of the proposed biosensor has been investigated in terms of variation in drain current, threshold voltage, subthreshold swing, ON/OFF current ratio, and transconductance characteristics. The proposed bio-sensor demonstrates drain current sensitivity of 7.82× 10^10 , I _ON /I _OFF ratio sensitivity of 2.01× 10^9 , and trans-conductance sensitivity of 2.32× 10^12 for T47D (a breast cancer cell line). Additionally, the proposed biosensor’s selectivity, linearity, and noise characteristics are evaluated in this study too. Furthermore, the sensitivity of the DM-PC-TFET biosensor has also been investigated with variations in BCCs charge density, temperature, device geometry, and non-uniform arrangement of cancer cell lines within the nano-cavity region. The simulation results of the proposed biosensor are generated using a 2D technology computer-aided design tool. The results demonstrate that the proposed biosensor can be used as a suitable and efficient nano-device for the early detection of breast cancer.

In this paper, the performance of dual-material stacked gate oxide-source dielectric pocket-tunnel field-effect transistor (DMSGO-SDP-TFET) has been investigated by considering fixed interface trap charges (ITCs) at the Si–SiO 2 interface. During the analysis, both types of trap charges, positive (donor) and negative (acceptor), have been considered to investigate their effect on the DC, analog/ radio frequency, linearity and harmonic distortion performance parameters in terms of the carrier concentration, electric field, band-to-band tunneling rate, transfer characteristics, transconductance ([Formula: see text]), unity gain frequency ([Formula: see text]), gain–bandwidth product, device efficiency ([Formula: see text]/[Formula: see text]), transconductance frequency product, transit time ([Formula: see text]), second- and third-order transconductance and voltage intercept points ([Formula: see text], [Formula: see text], VIP2 and VIP3), third-order Input Intercept Point and Intermodulation Distortion (IIP3, IMD3), second-, third-order and total harmonic distortions (HD2, HD3 and THD), respectively. Further, the impact of temperature variations from [Formula: see text][Formula: see text]K to [Formula: see text][Formula: see text]K in the presence of ITCs is investigated and the results are compared with conventional DMSGO-TFET. In terms of percentage variation, DMSGO-SDP-TFET depicts lower variation than conventional DMSGO-TFET, indicating that the proposed device is more immune to trap charges and can be used for energy-efficient, high-frequency and linearity applications at elevated temperatures.

The tunnel field-effect transistor (TFET) has emerged as a promising device for biosensing applications due to band-to-band tunneling (BTBT) operation mechanism and a steep subthreshold swing. In this paper, an electrically doped cavity on source junctionless tunnel field-effect transistor (ED-CS-JLTFET)-based biosensor is proposed for label-free detection of biomolecules. In the proposed model, the electrically doped concept is enabled to reduce fabrication complexity and cost. In order to create a nano-cavity at the source region, some portion of the dielectric oxide of the polarity gate terminal is etched away. To perceive the presence of biomolecules, two important properties of biomolecules, such as dielectric constant and charge density, are incorporated throughout the simulation. The sensing performance of the proposed ED-CS-JLTFET-based biosensor has been analyzed in terms of transfer characteristics, threshold voltage and subthreshold swing. In addition, the sensitivity of the proposed biosensor has also been analyzed with respect to different fill factors (FFs), varying nano-cavity dimension and work-function of the control gate. It is found from the simulated results that the proposed ED-CS-JLTFET-based biosensor offers higher current sensitivities with neutral, positively charged and negatively charged biomolecules of [Formula: see text] (at k [Formula: see text]), [Formula: see text] (at [Formula: see text] and [Formula: see text] C[Formula: see text]cm[Formula: see text]) and [Formula: see text] (at k [Formula: see text] and [Formula: see text] C[Formula: see text]cm[Formula: see text]), respectively.

The electrostatic doping technique has a remarkable ability to reduce random dopant fluctuations (RDFs), fabrication complexity and high thermal budget requirement in the fabrication process of nano-scale devices. In this paper, for the first time it has been propose and simulated a junction-free electrostatically doped tunnel field-effect transistor (JF-ED-TFET) based biosensor for label-free biosensing applications. The dielectric modulation concept has been used to sense biomolecules using a nano-cavity incorporated within the gate oxide layer near to the source end. The sensing response of the JF-ED-TFET biosensor has been analyzed in terms of the electric field, energy band and transfer characteristic and sensitivity in terms of ON-current, ION/IOFF ratio and subthreshold swing. The sensitivity of the biosensor has been investigated based on practical challenges such as different filling factors and step-profiles generated from the steric hindrance. The effect of temperate and nano-cavity dimension variations on device performance has been also analyzed. In this work, various types of biomolecules such as Streptavidin (k = 2.1), Ferro-cytochrome c (k = 4.7), keratin (k = 8) and Gelatin (k = 12) has been considered for the performance investigation.

In this paper, a polarity control, SiGe-source, Tunnel Field-Effect transistor (PC-SiGe-TFET)-based biosensor has been proposed for label-free detection of biomolecules. The $\mathbf{n}^{+}$drain and $\text{P}^{+}$source regions are created in the intrinsic silicon-SiGe body of the proposed device by using the polarity-controlled concept. In addition, a nano-cavity is created in the gate oxide towards the tunneling junction to modulate the tunneling mechanism via the immobilized biomolecules. The sensing performance of the proposed PC-SiGe-TFET biosensor is analyzed employing four different types of biomolecules, namely Biotin $(k=2.1)$, 3-aminopropylteriethoxysilane $(k=3.57)$, Femo-cytochromr-c $(k = 4.7)$ and Bacteriophage T7 $(k=6.3)$. The PC-SiGe-TFETbased biosensor exhibits higher sensitivity in terms of drain current $(\mathbf{I}_{DS})$, threshold voltage $(\mathbf{V}_{Th})$, and subthreshold swing (SS) and ON-OFF current ratio $(\mathbf{I}_{ON}/\mathbf{I}_{OFF})$. The sensitivity of the proposed biosensor has been evaluated with both neutral and charged biomolecules. The sensitivity of the PC-SiGe-TFET biosensor has also been investigated in terms of nano-cavity dimensions (length and width), as well as the various non-uniform step profiles (steric hindrances) of biomolecules in the nano-cavity.