Nanogap Cavity Research Articles

Analytical modelling and sensitivity analysis of Gallium Nitride-Gate Material and, dielectric engineered- Schottky nano-wire fet(GaN-GME-DE-SNW-fet) based label-free biosensor

An analytical model of nanogap embedded Gallium Nitride Gate- Material and Dielectric Engineered- Schottky Nano-Wire Field Effect Transistor (GaN-GME-DE-SNW-FET) for implementation as a label-free biosensor is introduced. An expression for the surface potential is attained by resolving the 1-D Poisson equation and 2-D Laplace equation utilizing a superposition method. A Model for the threshold voltage is also developed to analyze the sensitivity of the biosensor. The projected model also contains the repercussion of barrier height dropping at the metal-semiconductor intersection along with Dielectric Engineering (DE) using high-k (HfO2) material and Gate Material Engineering (GME) using metal m1with workfunctionφm1and m2with workfunctionφm2. The sensitivity of biosensor's has been studied for diverse dielectric constant and charge densities immobilized within the nanogap cavity. A comparative study has also been done between Gallium nitride-based (GaN- GME-DE-SNW-FET) and Silicon-based (Si-GME-DE-SNW-FET) Label-free biosensors. The developed analytical model is verified and validated using ATLAS- TCAD device simulations.

L-Shaped High Performance Schottky Barrier FET as Dielectrically Modulated Label Free Biosensor.

In this work, we demonstrate the realization of L-Shaped Schottky Barrier FET as a biosensing device with improved sensitivity. The proposed device uses dual material gate with work functions of 4.2 eV (Al) and 4.8 eV (Cu) and Hafnium Oxide (HfO₂) as the gate dielectric. In order to detect the biomolecule, a nano-gap cavity is created in the vertical gate (Gate1) by etching out the oxide. The electrical characteristics of biomolecules such as dielectric constant and charge density modulate the Schottky Barrier width, which in turn, changes the drive current of the device. Various sensitivity parameters have been thoroughly investigated at [Formula: see text] and a comparative analysis with the conventional device has been performed. The results so obtained reveal that [Formula: see text] sensitivity of the proposed device is much better for both neutral as well as charged biomolecules (maximum of 21x for neutral, at K = 12; 20x for charged biomolecules at ρ = -5×10 ¹⁰cm^-2, at K = 12). Besides this, the [Formula: see text] sensitivity, transconductance ( [Formula: see text]) sensitivity and selectivity show similar improvements. Further, the proposed device shows better sensitivity performance at low as well as at higher temperatures as compared to the state-of-the-art biosensing devices.

Vertical gate cavity bulk-planar junctionless FET-based biosensor for label-free detection of biomolecules

In this paper, we propose a vertical gate bulk-planar junctionless field-effect transistor (VGC-BPJLFET)-based biosensor for the label-free detection of neutral and charged target biomolecules. The vertical gate structure exhibits better performance due to high gate controlability in the channel region, which improves the drain current of the device. The enhancement in drain current significantly increases the sensing capability of the biosensor. To sense the neutral (APTES, biotin, streptavidin, protein, etc) and charged (deoxyribonucleic acid (DNA)) target biomolecules, the VGC-BPJLFET biosensor includes a vertical nanogap cavity in between the gate electrodes of the device in which HfO2 behaves as the functionalization layer. However, for the detection of both neutral and charged biomolecules, the two electric parameters (dielectric constant (K) and the charge density (ρ)) are considered in the etched nanogap cavity. Furthermore, to see the potentiality of the VGC-BPJLFET biosensor, the proposed biosensor has been compared to the lateral gate cavity BPJLFET biosensor in terms of drain current, sensitivity, linearity and signal-to-noise ratio characteristics. From the comparison, it has been observed that the proposed device has a higher sensitivity of ∼104 and ∼103 with the conjugation of neutral (APTES (K = 3.57)) and charged (DNA (ρ = −1 × 1011 cm−2)) biomolecules, respectively. The VGC-BPJLFET biosensor also carries the better sensing capability to sense the target biomolecules with the presence of unwanted (air) biomolecules in the etched nanogap cavity.

Design of a Double Cavity Nanotube Tunnel Field-Effect Transistor-based Biosenser

The manuscript focused on the concept of junction-less tunnel transistor to suggest and simulate the dielectric modulated double cavity nanotube TFET as a biosensor. The proposed biosensor worked as a label-free detector about dielectric constant (K) and charge density (ρ). In this, for neutral biomolecules (streptavidin and 3-aminopropyl-triethoxysilane (APTES)) and charged biomolecule (deoxyribonucleic acid (DNA)) are used for detection by the proposed sensor. The inner and outer cavities of the nanotube biosensor provide a large area for the stabilization of biomolecules and use the benefits of material solubility. The sensing capability of the proposed device investigates various DC performance parameters for the different dielectric biomolecules and charge densities. Further, the effect of substitution of SiO2 gate insulating layer by HfO2 also studies the sensing capability of the proposed biosensor. Moreover, a relative study of the biosensor for the presence and absence of inner and outer nanogap cavities performs in terms of different DC components to analyze the sensitivity variation.

Room-Temperature Strong Coupling Between a Single Quantum Dot and a Single Plasmonic Nanoparticle.

A single quantum dot (QD) strongly coupled with a plasmonic nanoparticle yields a promising qubit for scalable solid-state quantum information processing at room temperature. However, realizing such a strong coupling remains challenging due to the difficulty of spatial overlap of the QD excitons with the plasmonic electric fields (EFs). Here, by using a transmission electron microscope we demonstrate for the first time that this overlap can be realized by integrating a deterministic single QD with a single Au nanorod. When a wedge nanogap cavity consisting of them and the substrate is constructed, the plasmonic EFs can be more effectively "dragged" and highly confined in the QD's nanoshell where the excitons mainly reside. With these advantages, we observed the largest spectral Rabi splitting (reported so far) of ∼234 meV for a single QD strong coupling with plasmons. Our work opens a pathway to the massive construction of room-temperature strong coupling solid qubits.

Actively Tunable Metasurfaces via Plasmonic Nanogap Cavities with Sub-10-nm VO2 Films.

Actively tunable optical materials integrated with engineered subwavelength structures could enable novel optoelectronic devices, including reconfigurable light sources and tunable on-chip spectral filters. The phase-change material vanadium dioxide (VO2) provides a promising solid-state solution for dynamic tuning; however, previous demonstrations have been limited to thicker and often rough VO2 films or require a lattice-matched substrate for growth. Here, sub-10-nm-thick VO2 films are realized by atomic layer deposition (ALD) and integrated with plasmonic nanogap cavities to demonstrate tunable, spectrally selective absorption across 1200 nm in the near-infrared (NIR). Upon inducing the phase transition via heating, the absorption resonance is blue-shifted by as much as 60 nm. This process is reversible upon cooling and repeatable over more than ten temperature cycles. Dynamic, ultrathin VO2 films deposited by ALD, as demonstrated here, open up new potential architectures and applications where VO2 can be utilized to provide reconfigurability including three-dimensional, flexible and large-area structures.

Analytical Modeling of MgZnO/ZnO MOSHEMT Based Biosensor for Biomolecule Detection

In recent development, the High Electron Mobility Transistor (HEMT) technology was used for biosensor applications. In this contribution, an analytical model of MgZnO/ZnO MOSHEMT (Metal Oxide Semiconductor HEMT) was reported. For the first time, a nanogap cavity-based biosensor aimed at detecting various biomolecules, such as uricase, streptavidin, ChOx, and proteins, was designed. The developed analytical model was used to calculate the two-dimensional electron gas (2DEG) density, device capacitance, drain current (ID), output conductance (gd), and transconductance (gm) by using the dielectric modulation approach. MOSHEMTs used dielectric modulation, with the nanogap cavity considered under the gate region. The effective capacitance in the cavity region was obtained by using dielectric modulation. Hence, the nanogap cavity acts as a sensing area for the immobilisation of target biomolecules. The sensitivity of the device was analysed by observing the strong changes in drain current with the addition of different biomolecules in the nanogap cavity region. The proposed MgZnO/ZnO MOSHEMT biosensor exhibits a quick response to biomolecule changes since its drain-on-sensitivity (SIon) is comparatively higher than that of other semiconductor-based biosensors. The obtained analytical model results were verified by a comparison with other works available in the literature, and they showed good agreement with our results.

Ultrafast Lifetime and Bright Emission from Graphene Quantum Dots Using Plasmonic Nanogap Cavities.

Graphene quantum dots (GQDs) are quasi-zero-dimensional, carbon-based luminescent nanomaterials that possess desirable physical properties, such as high photostability, low cytotoxicity, good biocompatibility, and excellent water solubility; however, their long radiative lifetimes significantly limit their use in, e.g., light emitting devices where a fast spontaneous emission rate is essential. Despite a few reports on GQD fluorescence enhancements using metal nanostructures, studies of enhanced spontaneous emission rate remain outstanding. Here, we report fast and bright luminescence by coupling gap plasmon modes to nanoparticle emitters. Through precise control over the nanoparticle's local density of states (LDOS), we achieved a 220-fold increase in the PL intensity. The shortest radiative lifetime obtained was below 8.0 ps and limited by the instrument response, which is over 288-fold shorter than the lifetime of uncoupled GQDs. These findings may benefit the future development of rapid displays and open the possibility of constructing high-frequency classical or quantum telecommunication systems.

Sensitivity Measurement for Bio-TFET Considering Repulsive Steric Effects With Better Accuracy

Sensitivity analysis of label free Bio-TFET considering repulsive steric effects (RSEs) has been addressed in the paper. Doping-less underlap dielectric modulating tunnel field effect transistor (DU-DM-TFET) is assumed like a reference structure. Initially, the efficacy of doping-less underlap (DU) TFET without cavity has been compared with the reported TFET literatures. Later, the impact on surface potential (ψ), energy band (EB), ON-current (I <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">ON</sub> ), I <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">ON</sub> /I <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">OFF</sub> ratio, sub-threshold swing (SS), and their corresponding sensitivity due to variations of permittivity (k) along with charge density (N <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">f</sub> ) of bioanalytes, length of cavity (L <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">cavity</sub> ) and cavity thickness (T <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">cavity</sub> ) have been addressed in this context. Non-uniform patterns of bioanalytes inside the nanogap cavity regions considering impulsive steric effects make the analysis more practical. Later, an assessment of noise features inside the cavity of DU-DM-TFET based biosensor is explored. Finally, an error assessment table is prepared to evaluate sensitivity errors (S <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">E</sub> ) in the reported literature using the proposed RSE. A maximum 40% error in effective capacitance has been found if RSE is not considered. So, RSEs need to be considered always during the analysis of label free biosensing.

Design and Investigation of Dielectrically Modulated Dual-Material Gate-Oxide-Stack Double-Gate TFET for Label-Free Detection of Biomolecules

This article investigates the applicability of dual-material gate-oxide-stack double-gate tunnel field effect transistor (DMGOSDG-TFET) as a biosensing element with the ability to assess the health parameters and disease onset. For this, employment of gate work-function engineering along with the gate-oxide-stack approach and asymmetrical doping at <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${p}^{+}$ </tex-math></inline-formula> source and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${n}^{+}$ </tex-math></inline-formula> drain region are introduced for the first time to implement DMGOSDG-TFET-based biosensor. Also, a nanogap cavity is created by etching a portion of gate dielectric material toward the source end for the accomplishment of biomolecules conjugation in the proposed device. The main focus of this article is to estimate the underlying device sensitivity in the presence of different charged as well as neutral biomolecules. To explore such effects, different dielectric constants and negative charge densities of the biomolecules are considered independently in the nanogap cavity. Next, the sensing performance of the presented device is analyzed in terms of switching-ratio ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${I}_{ \mathrm{\scriptscriptstyle ON}}/{I}_{ \mathrm{\scriptscriptstyle OFF}}$ </tex-math></inline-formula> ), transconductance-to-current ratio ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${g}_{m}/{I}_{ds}$ </tex-math></inline-formula> ), and average subthreshold-swing. A deep investigation of device performance is also performed with different fillings of the nanogap cavity and step-profiles arising out from the steric hindrance. The device sensitivity is analyzed for different cavity lengths and cavity thicknesses for the best outcomes. In addition, a comparative sensitivity analysis of DMGOSDG-TFET with single-material gate-oxide-stack double-gate tunnel field effect transistor (SMGOSDG-TFET) and metal–oxide–semiconductor field effect transistor (MOSFET)-based biosensor is also presented in this work. The device implementation and all the simulations are carried out using technology computer-aided design (TCAD) tool. All of the sensitivity-assessments disclose that DMGOSDG-TFET can be a good candidate for biosensing applications.

Dielectric modulated GaAs1− x Sb X FinFET as a label-free biosensor: device proposal and investigation

In this paper, we propose and investigate a dielectric modulated (DM) GaAs1−x Sb x FinFET as a label-free biosensor. Raised source drain (RSD) architecture is employed in the proposed structure, resulting in a large surface to volume ratio, which provides more living space to the biomolecules. GaAs1−x Sb x is used as a channel material, which bestows higher carrier mobility and consequently offers better sensitivity than previously reported FET-based biosensors. In our proposed RSD GaAs1−x Sb x FinFET, we have embedded a nanogap (∼5.5 nm thickness) cavity between the gate and the channel region at which biomolecules can reside in a dry environment. The presence of biomolecules (charged or neutral) in the embedded nanogap cavity of a DM biosensor could be identified by the change in various electrical parameters such as ON–OFF current ratio (CR), threshold voltage (V th), transconductance, and intrinsic gain, etc, with the change in dielectric constant (K) of the cavity region. We found the maximum sensitivity corresponding to K = 12 is 48.91% and 26.31% for CR and V th, respectively. The governing physics to observe the substantial changes due to the velocity overshoot, capacitive coupling, and DIBL is thoroughly explained. The analysis of how one cavity of the proposed biosensor works at a time is also investigated. In our work, we have also identified the impact of biomolecules which carry charges by including trap models in numerical TCAD simulations.

Design and Performance Assessment of Dielectrically Modulated Nanotube TFET Biosensor

The manuscript proposes a novel charge plasma-based junctionless silicon dual cavity nanotube tunnel field-effect transistor (DC-NT-TFET) based biosensor for the detection of neutral and charged biomolecules. For improved sensing ability, the nanogap cavity is introduced in the inner as well as the outer portion of the NT-TFET. Also, the vertical orientation of the device enhances the even distribution of the biomolecules within the cavity area. The inner cavity provides more space for immobilization of the biomolecules and utilizes the advantages of material solubility. In this manuscript sensitivity of the proposed biosensor is Investigated for four neutral biomolecules of dielectric constant, streptavidin (k =.1), biotin (k = 2.63), 3-aminopropyl-triethoxysilane (APTES) (k = 3.57), and protein (k = 8). Also, charged biomolecule, deoxyribonucleic acid (DNA) with a specific dielectric constant of k = 6 is examined for different positive as well as negative charge density. The sensing capability of the device is analyzed in terms of various DC and RF performance parameters. Also, outer cavity length optimization and on various biomolecules are analyzed in the manuscript.

Investigation of Structural Parameters Impact on Sensitivity of InP/InGaAs/InP Channel Double Gate MOSFET for Biosensing Application

A simulation-based study of sensitivity parameters of hetero (InP/InGaAs/InP) channel with source-side cavity double gate MOSFET (H-SCDG MOSFET) to detect the label-free biomolecules like uricase (K=1.54), streptavidin (K=2.10), ferrocytochrome C (K=4.7), and protein (K=8) has been done. A nanogap cavity is embedded beneath the gate oxide segment to trap the bio-targets, which gives the deviation in threshold voltage. By incorporating the dielectric modulation method, the sensitivity analysis has been done with the variation in structural parameters of the device. The impact of sensitivity with a variation of cavity length (Lcavity) and oxide thickness (tox) is also examined. The ample performance of H-SCDG MOSFET has been extensively studied by using the 2D TCAD platform. It is observed that the protein biomolecule shows the value of sensitivity, on current sensitivity and subthreshold swing sensitivity as 0.53, 1.75, and 0.96, respectively, with Lcavity=15nm and tox=1nm.

Sensitivity Analysis on Dielectric Modulated Ge-Source DMDG TFET Based Label-Free Biosensor

This work compares the performance of dielectric modulated (DM) based Ge-source dual material double gate (DMDG) Tunnel Field Effect Transistor (TFET) and conventional (C)-DMDG-TFET as label free biosensor through Technology Computer Aided Design (TCAD) simulator. Here, cavity is introduced both at source and drain sides of the fixed HfO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> dielectric to increase the capture area of biosensors. Sensitivity (S <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">n</sub> ) is extracted for both neutral and charged (positive/negative) biomolecules considering cavity is fully filled with different dielectric materials (k). We have reported the sensitivity with the variation in height of nanogap cavity (h <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">bio</sub> ) for neutral biomolecules in the cavity. The sensitivity of Ge-source DMDG-TFET is found higher than C-DMDG-TFET due to more conduction at the tunnel junction. Also, the subthreshold swing (SS), transfer characteristics, and I <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">ON</sub> /I <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">OFF</sub> ratio of these biosensors are reported for different k and h <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">bio</sub> considering neutral/charged biomolecules. The sensitivity of partially filled nanogaps with biomolecules like decreasing, increasing, concave, and convex step profiles are reported for both the biosensors. The dynamic range (DR) of both the biosensors are extracted in presence of positive and negative charged biomolecules. The response time of Ge-source DMDG-TFET is reported at different k. A comparative study of proposed biosensor with other reported work is discussed. Finally, the sensitivity is extracted for DMDG-TFET considering other source material like GaAs, InAs, Si-Ge hetero stacked (HS), GaAs-InAs HS.

Role of Corner-Effect and Channel Epilayer Thickness on the Performance of a Unique pTFET-Based Biosensor (epiCOR-pTFET-Biosensor) Device in Sub-100-nm Gate Length

In this paper, for the first time, a unique pTFET-based biosensor device having channel epilayer has been introduced and its performance in the sensing domain has been studied in terms of five different sensitivity parameters. A rigorous analysis of the effect of the existent corner point (corner-effect) in the proposed device architecture on the sensitivity metrics has been performed for five different channel epilayer thicknesses, covering five different types of protein-molecules, viz., Apomyoglobin, Myoglobin, Protein-G, Ferricytochrome-C, and Ferrocytochrome-C. This is followed by determining detectability and optimum length-window of nanogap cavity of the proposed sensor device for the successful detection. Interestingly, it has been found that the undesired corner-effect, generally known for its unfavorable impact on the electrical behaviors of the MOS-based structures, actually comes to the aid by enhancing the detectability of the proposed device compared to its equivalent conventional SOI pTFET sensor device by almost 67% (for Protein-G, Ferricytochrome-C, and Ferrocytochrome-C) and 50% (for Apomyoglobin and Myoglobin) yet maintaining significantly good values for the sensitivity metrics throughout. Furthermore, smaller epilayer thicknesses ensure smaller optimum length-window of the nanogap cavity, resulting in more scaled-down device, compared to larger epilayer thickness values. A position-dependent variability study for the detectability also follows, and it has been found that for small epilayer thicknesses this dependency becomes large leading to less stable device, although, at the same time producing higher sensitivity metrics compared to the devices having large epilayer thicknesses. This makes the choice of channel epilayer thickness as application-specific.

Design and Performance Analysis of Tunnel Field Effect Transistor With Buried Strained Si1−x Ge x Source Structure Based Biosensor for Sensitivity Enhancement

In this paper, a dielectrically modulated symmetrical double gate, having dual gate material, Tunnel Field-Effect transistor with Buried strained Si <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1-x</sub> Ge <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">x</sub> source structure, has been investigated as a biosensor. This structure is proposed for the very first time to electrically detect the biological molecules at very low power consumption. In the proposed biosensor structure, the top thin Si channel of TFET is overlapped with the Si <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1-x</sub> Ge <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">x</sub> source. This increases the tunneling area, due to which ON current of the biosensor also increases. To detect the biomolecules a nanogap cavity has been created over 1nm gate oxide. Also to decrease the short channel effects, dual-gate material with different metal work functions is used on both the symmetrical double gates. By varying the small bandgap material (Ge) mole fraction in the SiGe and after inserting different biological molecules (of the different dielectric) in a cavity, the variation in transfer characteristic, I <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">ON</sub> /I <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">OFF</sub> current ratio, SS along with their sensitivity is studied. Also, to signify the presence of biomolecules in the cavity, the g <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">m</sub> /I <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">d</sub> ratio as a sensing metric is studied under the sub-threshold region. Along with the fully filled biomolecules cavity, the partially filled cavity and the effect of a steric hindrance have also investigated in this paper with various non-uniform step patterns of biomolecules in the cavity. Because, in a more practical situation, the steric hindrance effect doesn't allow the cavity to be entirely filled. Also, this paper addresses the optimization of drain current sensitivity, by different cavity length with different source overlapping cavity.

Profound analysis on sensing performance of Nanogap SiGe source DM-TFET biosensor

This present work is an extensive effort to report the key role of indispensable technical challenges in the sensing performance of an embedded nanogap SiGe source dielectric-modulated tunnel field effect transistor (SGS-DM-TFET) biosensor during the conjugation of biological samples for the first time. In order to reach high and brilliant insights into the different design considerations impacting on the sensing performance of the biosensor under the study, two key issues in terms of process-related issue and real-time-related issues covering biomolecules manners in the nanogap cavity of the biosensor have been comprehensively studied through extensive numerical simulation. Investigations in this work revealed that the SGS-DM-TFET biosensor must be truly configured for working in realistic conditions. The obtained results give us a useful guideline for sensing the biomolecules samples in the real conditions including low coverage percentage of biological samples, charge effect, and discrete probe position with the help of SGS-DM-TFET biosensor while keeping the high sensitivity.

Simulation Study of Dielectric Modulated Dual Material Gate TFET Based Biosensor by Considering Ambipolar Conduction

In this paper, a dielectric modulated dual material gate TFET (DM-DMG_TFET)based biosensor is proposed. In order to detect various biomolecules, a nanogap cavity is formed by the overlapping the gate on the drain side. The change in ambipolar current is considered as the sensing parameter by changing the dielectric constants of various immobilized biomolecule inside the nano cavity. A complete investigation on the performance of the biosensor is also done by considering different positions and filling factor of the biomolecules inside the nano cavity region. The dual-material gate structure is considered with dissimilar work functions (фM1 < фM2), which can effectively reduce the ambipolar current by enhancing the barrier width at channel-Drain junction. The proposed structure deliberately reduces ambipolar current and increases the sensitivity as compared to the single material gate structure. In this work we report a drift in the sensitivity from 104 to 106 for low dielectric constant biomolecules.

A metasurface-based diamond frequency converter using plasmonic nanogap resonators

AbstractDiamond has attracted great interest as an appealing material for various applications ranging from classical to quantum optics. To date, Raman lasers, single photon sources, quantum sensing and quantum communication have been demonstrated with integrated diamond devices. However, studies of the nonlinear optical properties of diamond have been limited, especially at the nanoscale. Here, a metasurface consisting of plasmonic nanogap cavities is used to enhance both χ(2) and χ(3) nonlinear optical processes in a wedge-shaped diamond slab with a thickness down to 12 nm. Multiple nonlinear processes were enhanced simultaneously due to the relaxation of phase-matching conditions in subwavelength plasmonic structures by matching two excitation wavelengths with the fundamental and second-order modes of the nanogap cavities. Specifically, third-harmonic generation (THG) and second-harmonic generation (SHG) are both enhanced 1.6 × 107-fold, while four-wave mixing is enhanced 3.0 × 105-fold compared to diamond without the metasurface. Even though diamond lacks a bulk χ(2) due to centrosymmetry, the observed SHG arises from the surface χ(2) of the diamond slab and is enhanced by the metasurface elements. The efficient, deeply subwavelength diamond frequency converter demonstrated in this work suggests an approach for conversion of color center emission to telecom wavelengths directly in diamond.

Label-free detection of DNA by a dielectric modulated armchair-graphene nanoribbon FET based biosensor in a dual-nanogap setup.

A Double-Gate Armchair-Graphene Nanoribbon FET is proposed to realize a high-sensitive and small-size biosensor in order to detect DNA without high-cost and time-consuming labeling process. Two nanogap cavities open inside the top and bottom gate oxides by the method of sacrificed layer etching. When the DNA biomolecule is introduced to the nanogap cavity, the hybridization event which is actually the formation of a double-strand of DNA will occur thus electrically modulating the GNR channel leading to a change in the drain current. The important report of this research is about attained high sensitivity of the proposed biosensor for a vast spectrum of the DNA biological samples. It is worth noting that a DNA sequence by 23 nucleotides extracted from Neisseria gonorrhoeae can be detected as a special case. An extensive numerical approach has been applied in order to characterize the proposed biosensor. The suggested biosensor has been evaluated by solving Schrödinger equation )SE( with Non-Equilibrium Green Function (NEGF) method in the mode-space coupled into Poisson solver in a self-consistent manner assuming ballistic limit. Two different expressions of sensitivity in terms of the threshold voltage and current have been defined giving a good metric for the sensitivity analysis. The results revealed a relative sensitivity of 1mV/nm2 by a filled area by the DNA about 120nm2 showing the excellent superiority for the proposed biosensor as compared to other counterparts. The effective area of the proposed biosensor obtains 240nm2 which is very small in comparison with other reports highlighting high capability of the biosensor in the detection. It has been shown that the proposed biosensor can be implemented in ultra-scaling domain resulting in considerable increase in the sensitivity promising a potent and reliable candidate for high-sensitive and small-size biosensors. Also, the technical issues on designing the suggested biosensor have been investigated to achieve a useful guideline in detection and identification of the target DNAs.