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The design of a high-performance Dielectrically Modulated Field Effect Transistor (DMFET) with smaller device dimension (channel length ≤ 100nm) has recently drawn significant research attention for point-of-care (POC) diagenesis applications. Driven by this paradigm, a Hetero-Gate Metal Dielectrically Modulated Junction-Less Nanotube Field Effect Transistor (DM-JLNFET) architecture is introduced and systematically investigated for label-free electrochemical biosensing application with the help of extensive numerical device simulations. The DM-JLNFET is carefully designed to exploit the advantages of superior gate control over channel electrostatics and electron injection component as well as strong immunity towards the short channel effects that lead to a notably high sensing performance compared to its conventional counterparts. In this context, the underlying physics of the transduction mechanism is analyzed in detail based on the device electrostatics and the carrier transport mechanism. The sensing performance of the proposed biosensor is quantified in terms of the drain current and threshold voltage sensitivities, which represents the relative modulations in these parameters with biomolecule conjugation. Typically, the DM-JLNFET exhibits a drain current and threshold voltage sensitivities as high as 1×1012 and 0.70, respectively, for biomolecule dielectric constant above 2. Furthermore, the sensing performance demonstrates strong immunities towards non-uniform cavity occupancy. Finally, extensive comparative performance analysis with Dielectrically Modulated Nanowire Field Effect Transistor (DM-NWFET) is performed. The results exhibit that the proposed DM-JLNFET can offer more than 100% and eight orders of magnitude improvements in the threshold voltage and drain current sensitivities, respectively, for a range of small biomolecule dielectric constants.

From the perspective of sustainable environment and economic value, the electroreduction of CO2 to higher order multicarbon products is more coveted than that of C1 products, owing to their higher energy densities and a wider applicability.

Naphthalene diimide derivatives (NDI) have exhibited significant potential for sensing applications owing to their excellent photo-stability, environmental stability, reasonable electronic conductivity, and ability to form nanostructures with diverse morphologies through...

In this work, a Diagonal Tunneling Dielectrically Modulated Tunnel Field Effect Transistor (DT-DMTFET) architecture is proposed for label-free bio-sensing application. The performance of this sensor architecture is comprehensively investigated with the help of extensive numerical device simulations. The architecture has been carefully engineered to exploits the diagonal band to band tunneling (BTBT) component in favor of bio-molecule detection. The essential physics of the transduction mechanism for lateral tunneling, vertical tunneling, and diagonal tunneling-based DMTFETs is extensively analyzed from device electrostatics and transport mechanisms. The transduction efficiency of the sensor devices is quantitatively assessed in terms of current sensitivity, where DT-DMTFET exhibits a sensitivity of 3590 compared to 2514 and 1550 observed in lateral tunneling (LT) and vertical tunneling (VT) dominated DMTFETs, respectively. The optimum sensitivity of DT-DMTFET is observed at 4V and 0.4 V gate and drain biases ranges of operation, where the same is observed at a gate bias of 5V and 7V for LT- and VT- DMTFET, respectively. Furthermore, the device design aspects are studied in detail to identify the relevant structural parameters and subsequently optimize the sensing performance of the DT-DMTFET. Finally, an extensive comparative performance study establishes that the DT-DMTFETs offer more than 50% and 100 % improvements in the current sensitivity compared to their lateral and vertical tunneling-based counterparts, respectively, over a range of bio-molecule sample specifications.

Flexible pressure and strain sensors have gained popularity in various potential applications such as artificial e-skin, healthcare etc. However, the underlying transduction mechanism of pressure and strain sensors are often not studied in detail and only a qualitative analysis is presented which restricts the better understanding as well as design optimization of the system. In present work, a flexible pressure and strain sensor was fabricated using Tin disulfide (SnS2) deposited on paper substrate and enclosed in between Polydimethylsiloxane (PDMS). The sensors electrical characterization revealed a sensitivity of 106.83 kPa−1 and 22.83 for pressure and strain sensors respectively. The first principle calculation has been exploited to analyze the electronic properties of few layer SnS2 under applied tensile strain and normal pressure leading to a clear correlation between the underlying physics of strain/pressure and the electronic transport properties of SnS2 network. It has been observed that the effective masses significantly influence the inter SnS2 tunneling component which eventually determines the overall conductivity of the SnS2 network. The successful demonstration of both experimental and theoretical understanding of 2D materials based physical sensors opens up new avenues of research in flexible and wearable electronics.

The effect of three different interlayer stacking arrangements of bilayer (BL) molybdenum disulfide (MoS2) channel material on the device behavior of p- and n-metal–oxide–semiconductor field-effect transistors (MOSFETs) is extensively investigated using first-principles calculation based on density functional theory, emphasizing electronic properties such as the eigenstates, effective mass, band structure, and total energy of the BL-MoS2 for various stacking arrangements. The corresponding effects on the MOSFET device characteristics are then analyzed. The results indicate that the hole effective masses in both the longitudinal (transport) and transverse direction are highly sensitive to the interlayer stacking arrangement, and the performance of the p-MOSFET can be significantly tuned for a suitable stacking configuration of the BL-MoS2. Indeed, 24.12% and 31.37% improvements in the on-state current and transconductance are observed, respectively, for the p-MOSFET compared with the natural stacking arrangement of BL-MoS2. The ballistic BL-MoS2-based p- and n-MOSFETs with the tuned stacking arrangement demonstrate an on-state current on the order of 103 µA/µm along with an on-state/off-state current ratio greater than 103, a near-ideal (> 65 mV/decade) subthreshold swing, and small (

This work demonstrates the solution processed fabrication of a SnS2/graphene (Gr) heterojunction on a biodegradable cellulose paper substrate for its utilization as a broadband photodetector. Graphene was dip coated on cellulose paper followed by the direct growth of SnS2 on Gr/cellulose paper by a hydrothermal method. To study the charge transport mechanism of this unique heterojunction, first principles calculations are performed to theoretically estimate the band gap and the electron affinity values that lead to a detailed understanding of the band alignment in this heterojunction. There are no reports which demonstrate the direct large area growth of SnS2 on cellulose paper to fabricate an efficient broadband photodetector, complemented by a detailed theoretical understanding to understand the underlying physics of this device. The responsivity of the fabricated photodetector was calculated to be 6.98 and 3.67 mA W−1 for visible and UV light illumination respectively suggesting that the device was more responsive towards the visible spectrum when compared to the UV region. The durability of the photodetector was tested by subjecting it to 500 bending cycles wherein a negligible change in the responsivity values was observed. The successful fabrication of a large area SnS2/Gr heterojunction on a low-cost cellulose paper substrate with its performance metrics comparable to a device fabricated using sophisticated techniques is a major step ahead in the development of low-cost photodetectors which finds potential applications in security, visible light communication, etc.

In this work, the performance of a Double-Gated Silicon on Insulator (DG-SOI) Dielectrically Modulated Tunnel Field Effect Transistor (DMTFET) architecture is systematically investigated for label-free bio-sensing applications with the help of extensive device-level simulations. In this context, the effects of bulk oxide (BOX) substrate and back-gate biasing are emphasized and analyzed from the cavity and channel electrostatics and Band to Band Tunneling (BTBT) component of DMTFET. It is found that the electrostatic coupling between BOX substrate and channel significantly degrades the sensing performance of DG-SOI DMTFETs, whereas an applied negative back-gate bias enhances the performance of such transducer. In this line, a dual metal (DM) gate architecture is introduced that can effectively enhance the influence of applied back-gate bias and thereby leads to sensitivity improvement from 10% to 110% in DM DG-SOI DMTFET depending on bio-molecule sample specifications. Furthermore, it is observed that for suitable applied back-gate bias, the interface trap-state induced variations in sensitivity of DG-SOI DMTFETs can be reduced by even an order of magnitude. Finally, a comparative sensing performance study of proposed DMTFET with their reported counterparts establishes the advantage of such biosensors for bio-molecules with smaller dielectric constant. A similar study also shows the superiority of the proposed DMTFET over its MOSFET counterpart for wide bio-molecular sample specifications.

In this work, a copper-doped (5%) zinc oxide (Cu:ZnO) ferroelectric materials-based memristor model was realized and it was employed to develop principal component analysis (PCA), a data dimension reduction technique. The developed PCA was utilized to efficaciously classify breast cancer datasets, which are considered as complex and big volumes of data. It was found that the controllable memristance variations were analogous to the weight modulations in the implemented neural network-based learning systems. Sanger’s rule was utilized to achieve unsupervised online learning in order to generate the principal components. On one side, the developed memristor-based PCA network was found to be effective to isolate distinct breast cancer classes with a high classification accuracy of 97.77% and the error in the classification of malignant cases as benign of 0.529%, a significantly low value. On the other side, the power dissipation was found to be 0.27 µW, which suggests the proposed memristive network is suitable for low-power applications. Further, a comparison was established with other existing non-memristor and non-PCA-based data classification systems. Furthermore, the devised less complex equations to implement PCA on this memristive crossbar array could be employed to implement any neural network algorithm.

In this paper, detailed study has been explored on Si and SiC(4H) based avalanche transit time (ATT) sources for operation at frequencies under millimeter-wave and terahertz (THz) regimes. Drift–diffusion model has been used here to scrutinize the high frequency features of the device. Also, corresponding avalanche response time (ƬA) as well as transit time (ƬT) has been ascertained to investigate device performance. The simulation studies show that the upward cut-off frequency levels of Si and SiC(4H) double-drift region (DDR) ATTs are 500 GHz and 1.0 THz, respectively. The finding here is that SiC (4H) upon IMPATTs are highly favorable for generation of power with significant efficiency at higher frequencies due to smaller value of avalanche response time.

The Gallium Selenide (GaSe) is one of the emerging members in the two-dimensional (2D) semiconductor family and being actively explored for electronic and optoelectronic applications. However, to this date, systematic theoretical investigations are yet to be observed on simultaneous effects of interlayer stacking arrangements and applied biaxial strains in few-layer GaSe for realizing tunable electronic and transport properties. In this work, the bilayer (2L) GaSe is considered in its natural as well as three energetically stable artificial interlayer stacking arrangements and is subjected to biaxial compressive and tensile strains. The subsequent modulations in the structural, electronic, and transport properties are systematically analysed from the in-plane, and inter-plane electronic redistributions using density functional theory (DFT) based first principle calculations. In this context, emphasis has been given to the energy bandgaps and effective masses of 2L-GaSe. The results indicate that strain and artificial stacking together can lead to significant changes in the in-plane and interlayer electronic distributions and, thereby, the electronic band structures and transmission spectrum of 2L-GaSe. The applied biaxial compressive strain appears highly effective for linearly tuning the bandgap and effective masses with noticeably different values for different stacking arrangements. Interestingly, under applied biaxial tensile strain, highly nonlinear variations in energy bandgap and effective mass are observed along with characteristic shifts in the position of conduction band minima (CBM) and Valence Band Maxima (VBM) for different stacking orientations. The key findings of this work offer detailed theoretical and design-level insight for strain/stacking co-optimization strategy in 2L-GaSe for realizing high-performance electronic and optoelectronic devices.

In this work, an inverter-based biomolecule detection strategy has been introduced for dielectrically modulated biosensing applications that show a clear output logic-state transition after conjugation. Subsequently, a bioring-oscillator has been realized based on such bioinverters, where biomolecules can be detected from the oscillation frequency amplification with conjugation. To optimize the detection efficiency, a dielectrically modulated fringing field effect transistor based transducer has been incorporated as the pull-up/pull-down elements of such bioinverter. The underlying physics of such structure has been investigated and subsequent electrical response has been estimated for various biomolecule sample specifications. This work explores different bioinverter configurations, and subsequently the suitable choice of bioinverter has been indicated for charged and charge-neutral biomolecule detection. Similar studies have been performed for bioring oscillator, and the roles of supply voltage scaling and oscillator stage enhancement have been investigated in this context.

In this work, for the first time, the tri-layer sandwiched Van der Waals heterostructures of SnS2 and MoSe2 are investigated using first principle calculations. In such heterostructures, a monolayer of SnS2 (MoSe2) is sandwiched between two MoSe2 (SnS2) layers. Subsequently, such heterostructures are considered in two different stacking orders, i.e. ABA and AAA corresponding to the natural stacking of bulk MoSe2 and SnS2, respectively. The structural and electronic properties of such tri-layer heterostructures are extensively analyzed in comparison with the homogeneous SnS2 and MoSe2 tri-layers. In this context, emphasis has been given on the bond length and bond angles of metal and chalcogen atoms at the sandwiched layers of heterostructures. Finally, the influences of the homogenous and heterogeneous sandwiched layers on the energy band structures have been analyzed in detail from the orbital projections of electronic states at the conduction band and valence band.

Dielectrically modulated tunnel FET (DMTFET)-based biosensors show higher sensitivity but lower subthreshold current compared with their dielectrically modulated FET counterpart. In this context, the effect of use of silicon–germanium (SiGe) source and n+-pocket-doped channel is investigated with the help of extensive device-level simulations. This paper explores the underlying physics of germanium composition variation in the source region, and doping concentration variation in n+-pocket region, from the perspective of biomolecule conjugation. The effects of source bandgap and tunneling length over the band-to-band tunneling component have been analyzed, and, subsequently, the sensing performance of DMTFETs has been estimated. The results show that SiGe-source DMTFET has significant superiority over n+-pocket DMTFET for attaining higher subthreshold current level while retaining acceptable sensitivity. Such sensitivity-current optimization has been studied for different gate and drain biases, and the suitable biasing range of operation has been indicated. In addition, the relative efficiency of SiGe source and n+-pocket-doped channel has been studied under different biomolecule sample specifications. Finally, the influence of trap-assisted tunneling on DMTFET sensing performance has been analyzed, and the comparative role of SiGe source and n+ pocket has also been indicated in this context.

In this investigation, chemically synthesized 5% copper doped ZnO (Cu:ZnO) thin films were deposited onto ITO/Glass using sol-gel spin coating method. Firstly, the effects of inclusion of Cu doping on the electronic properties of ZnO were studied using Density Functional Theory (DFT) based first principle calculations. The comparative energy band (E-k) and orbital projections of density of states profiles were extensively analysed to understand the electronic activities of Cu induced defect states in Cu:ZnO. X-ray photoelectron spectroscopy (XPS) analysis was performed to confirm the oxidation states of Zn, Cu and O and also confirm the existence of oxygen vacancy oriented defects in the Cu:ZnO films. This analysis also indicates that Cu existed in +2 valence state. The experimentally obtained results were compared with the theoretical analysis and both were closely matched. Furthermore, extended x-ray absorption fine structure (EXAFS) and x-ray absorption near edge structure (XANES) characterizations were also employed to study the role of oxygen vacancies, ions and defect states in Cu:ZnO, which play a pivotal role in the operation of resistive switching devices. XANES and EXAFS have confirmed that Cu conveniently replaced the Zn atoms within the crystal lattice in the deposited films. To investigate the temperature dependent charge transport mechanism, the resistivity of the Cu:ZnO films was measured in the temperature range of 10–300 K. It was ascertained that above 115 K, thermally activated type of conduction governs the charge carrier transport, whereas Mott's variable range hopping type of conduction mechanism is prevalent below 40 K.

In this embedded tutorial, a comprehensive account of dielectrically modulated biological field effect transistor (DM-BioFET) has been presented. The tutorial offers a general overview on BioFET, indicating the underlying physics of charge-modulated and dielectric-modulated transduction mechanism. Next, gradual developments in DM-BioFET have been discussed, and the effects of device downscaling on transduction performance has been typically emphasized. Subsequently, different DM-BioFET designs for transducer performance optimization has been analyzed from their device electrostatics and carrier transport mechanism. The comparative merits/ demerits of such emerging variants of DM-BioFET are also indicated in this context. In essence, the tutorial attempted to convey a clear understanding of DM-BioFET based biosensors for general readers, and the present research scenario, future promises as well as research challenges of this domain are duly elaborated for interested researchers.

In this paper, a short-gate tunneling-field-effect-transistor (SG-TFET) structure has been investigated for the dielectrically modulated biosensing applications in comparison with a full-gate tunneling-field-effect-transistor structure of similar dimensions. This paper explores the underlying physics of these architectures and estimates their comparative sensing performance. The sensing performance has been evaluated for both the charged and charge-neutral biomolecules using extensive device-level simulation, and the effects of the biomolecule dielectric constant and charge density are also studied. In SG-TFET architecture, the reduction of the gate length enhances its drain control over the band-to-band tunneling process and this has been exploited for the detection, resulting to superior drain current sensitivity for biomolecule conjugation. The gate and drain biasing conditions show dominant impact on the sensitivity enhancement in the short-gate biosensors. Therefore, the gate and drain bias are identified as the effective design parameters for the efficiency optimization.

In this work, electrochemical sensing of hydrazine is reported using laser induced flexible graphene as the sensing electrode. The electrodes were fabricated by simple lasing and patterning of polyimide films at ambient conditions. Cyclic voltammetry technique was used for electrochemical sensing of hydrazine. These sensors exhibited linear response to change in concentration of hydrazine. The sensor had a sensitivity of up to 115% at 0.5 mM hydrazine, limit of detection of 70 µM, and was reliable after 500 bending cycles. Overall, the hydrazine sensor exhibited good reproducibility, sensitivity, selectivity, lifetime, and is promising for developing low cost flexible hydrazine sensor.

In this letter, a transducer sensor is introduced that is based on the principle of charge plasma-enhanced tunnel field-effect transistor (CPE-TFET) structure for catalytic metal gate based electrochemical hydrogen (H2) gas detection using numerical device simulation. In the proposed sensor, the induced charge plasma at the source region is exploited for realizing a superior gate control over tunneling junction electrostatics that leads to a drain current sensitivity improvement near an order of magnitude over the conventional (Conv) TFET. The underlying physics of the proposed sensor is explored from a detailed electrostatic analysis of the tunneling junction in the context of gas molecule adsorption. In this effect, the sensitivity is estimated for the different gate and drain biases, and the suitable biasing range of operation is indicated. Furthermore, extensive structural optimization is performed to achieve a design-level understanding of CPE-TFET. Finally, the comparative performance analysis with Conv-TFET and mosfet establishes the inherent superiority of CPE-TFET for H2 gas sensing at different partial gas pressures and temperatures.

In this work, a Short Gate Insulator Less Dielectrically Modulated Tunneling Field Effect Transistor (SGIL-DMTFET) structure is explored in details for bio-sensing applications by using extensive device-level simulation. A comprehensive physical understanding is developed on the gate-engineering technique of DMTFET for bio-molecule conjugation. Such understanding is then successfully extended to analyze the working principle of SGIL architecture and its inherently superior current sensitivity over the conventional DMTFET. A comparative performance study has been performed on the basis of biasing conditions and the relevant biasing range of operations is indicated for both the DMTFETs. Further, the comparative sensing performance of DMTFETs is associated with their relative nature of threshold voltage shift (for conjugation) and sub-threshold swing. Finally, the cavity length and channel thickness are identified as the fundamental device parameters for optimizing sensitivity for both the biosensors.

In this work, the effect of Germanium mole fraction variation in the source region of a dielectrically modulated Silicon Tunneling Field Effect Transistor (DMTFET) based biosensor has been investigated with the help of extensive device-level simulation. Results show that the increasing germanium mole fraction significantly reduces the DMTFET sensitivity towards the bio-molecules, and the degree of this sensitivity degradation has strong dependence on the properties of bio-molecule namely dielectric constant and charge density. The increasing Germanium mole fraction reduces the effect of gate fringing field at the source region and consequently the conduction band lowering being diminished in this region, resulting in the sensitivity degradation in the DMTFET biosensor. This study offers a fair design level understanding over the use of Silicon-Germanium source in DMTFET based biosensor.

An analytical model for the 2D potential distribution in sub-threshold regime of operation of a SOI TFET structure under the assumption of a sinusoidal potential distribution in the direction perpendicular to the gate in the middle portion of the channel is developed. Role of any charge on the channel potential is neglected. The model predicts the transfer characteristics of the device with reasonable accuracy.

This work presents an extensive simulation study on different design parameters of an Extended Source Ultra Thin Body Double-Gated Tunneling Field Effect Transistor structure. The study investigates the effects of different device design parameter variations on electrical parameters like: sub-threshold swing, trans-conductance, ON-state current and OFF-state current. Finally an optimum structure for Extended Source Ultra Thin Body Double-Gated Tunneling Field Effect Transistor has been derived from the simulation study, with encouraging results for parameters of interest.

This paper presents a novel design scheme to reduce the short channel effects effectively in deep sub-micron MOSFET design. This scheme shows excellent improvement in the off-state current and proves to be very effective in controlling channel length modulation in nano-scale device design. This paper also proposes a subsequent theory to explain the effect of the design scheme on device characteristics supported by a through simulation study.

This paper presents a thorough simulation study on the various drive current improvement schemes on Double Gated Tunneling Field Effect Transistor. It also presents a band-gap engineering technique in order to increase the on-state current of the device. Qualitative analysis has been provided explaining the effect of these techniques on the device characteristics.