Tunneling Rate Research Articles

Investigation of Si 1−X GeX source dual material stacked gate oxide pocket doped hetero-junction TFET for low power and RF applications

ABSTRACT In this paper, the applicability of dual material stacked gate-oxide-Pocket doped-hetero-junction tunnel field effect transistor (DMSGO-PD-HTFET) for low power switching and radio frequency (RF) applications is investigated. In this context, gate workfunction engineering, the stacked-gate-oxide (+) approach, and asymmetrical doping at the P+ source () and N+ drain regions are considered. N+ pocket at source-channel interface implements DMSGO-PD-HTFET and improves interband tunnelling rate. This research aims to improve the device’s switching ratio (/), average subthreshold swing (), and radio frequency (RF) performance. For this, the control gate work function, mole fraction (X), pocket thickness, and doping concentration are optimised. Next, the DC, analog/RF and linearity figure of merits of the proposed device is analysed and the performance is compared with conventional all-silicon dual-material stack gate oxide tunnel field effect transistor (DMSGO-TFET) and dual-material stacked gate oxide-hetero-junction tunnel field effect transistor (DMSGO-HTFET) with source using technology computer-aided design (TCAD) device simulator. Based on the comparative analysis, the optimised design with exhibits an average subthreshold swing () of 28.8 mV/decade, switching ratio (/) of 2 × 1012, cut-off frequency () of 216 (GHz), and other significant improvements in analog/RF and linearity performance parameters. The proposed device is therefore suitable for switching and RF applications.

Probing flux and charge noise with macroscopic resonant tunneling

We report on measurements of flux and charge noise in an rf-SQUID flux qubit using macroscopic resonant tunneling (MRT). We measure rates of incoherent tunneling from the lowest energy state in the initial well to the ground and first excited states in the target well. The result of the measurement consists of two peaks. The first peak corresponds to tunneling to the ground state of the target well, and is dominated by flux noise. The second peak is due to tunneling to the excited state and is wider due to an intrawell relaxation process dominated by charge noise. We develop a theoretical model that allows us to extract information about flux and charge noise within one experimental setup. The model agrees very well with experimental data over a wide dynamic range and provides parameters that characterize charge and flux noise.

Tunneling potential actions from canonical transformations

A new formulation for obtaining the tunneling action for vacuum decay based on the so-called tunneling potential was developed recently. In the original derivation, the new actionwas obtained by requiring that its variation led to the correct equations of motion and the same value for the action as evaluated on the Euclidean bounce. We present an alternative derivation of the tunneling potential action via canonical transformations. We discuss both single-field and multi-field cases as well as the case with gravity. We also comment on the possible application of the new approach to the calculation of the functional determinant prefactor in the tunneling rate.

Tunneling and thermodynamics evolution of the magnetised Ernst-like black hole

We investigate the tunneling phenomenon of particles through the horizon of a magnetized Ernst-like black hole. We employ the modified Lagrangian equation with the extended uncertainty principle for this black hole. We determine a tunneling rate and the related Hawking temperature for this black hole by using the WKB approach in the field equation. In addition, we examine the graph behavior of the Hawking temperature in relation to the black hole event horizon. We explore the stability analysis of this black hole by taking into account the impact of quantum gravity on Hawking temperatures. The temperature for a magnetised Ernst-like black hole rises as the correction parameter is decreased. Moreover, we analyze the thermodynamics quantities such as Hawking temperature, heat capacity and Bekenstein entropy by using the different approach. We obtain the corrected entropy to study the impact of logarithmic corrections on the different thermodynamic quantities. It is shown that these correction terms makes the system stable under thermal fluctuations.

Theory for polaritonic quantum tunneling

I investigate the tunneling decay rate of a polaritonic system formed by a strong coupling between a vacuum cavity mode and $N$ metastable systems. Using a simple model potential, I find the instanton solutions controlling the low-temperature tunneling rate. The resulting rate modification due to the cavity is proportional to the mean of the second power of the light-matter coupling. No collective effect that would enhance the rates by a factor of $\sqrt{N}$ is present, which is in line with the results in the thermal activation regime.

Dependence of RF/analog and linearity parameters on ferroelectric layer thickness in ferroelectric tunnel junction dual material double gate (FTJ-DMDG) TFET

In this article, we have proposed a ferroelectric tunnel junction (FTJ) dual material double gate (DMDG) TFET using TCAD simulator, where a ferroelectric (FE) layer is incorporated at tunnel junction to increase the band to band tunnelling rate. TCAD simulation result reflects that the inclusion of FE layer leads to improved ON current with enhanced BTBT rate as the thickness of FE layer (t FE) is reduced from 4 to 2 nm. The RF/analog parameter like transconductance (g m), gain (g m/g d), cut off frequency (f t), transconductance generation factor (TGP), gain frequency product (GFP), and transconductance frequency product (TFP) are improved by noticeable amount with down scaling in t FE value. The linearity analysis like g m2, g m3, voltage intercept points (VIP2 and VIP3), power intercept point (IIP3), and 1-dB compression point are also highlighted in FTJ-DMDG-TFET by varying t FE. A noticeable improvement in linearity behaviour is perceived with increased value in t FE.

Breast-Cancer Biomarker (C-erbB-2) Detection in Saliva/Serum Based on In1-xGaxAs/Si Hetero Junction Dopingless TFET Biosensor.

This research article reports the electrical detection of breast-cancer biomarker (C-erbB-2) in saliva/serum based on In1-xGaxAs/Si heterojunction dopingless tunnel FET (HJ-DL-TFET) biosensor for highly sensitive and real-time detection. The work takes into account the interface charge modulation effect in dopingless extended gate heterostructure TFET with embedded nanocavity biosensors for the precise, reliable, and fast detection of antigens present in the body fluids such as saliva in place of blood serum. The reported biosensor is numerically simulated in 2D using the SILVACO ATLAS exhaustive calibrated simulation framework. For the biomolecule immobilization, the proposed biosensor has a dual cavity engraved beneath the dual gate structure. This improves the control of biomolecules over the source-to-channel tunneling rate, as well as the control over the electrical performance parameters of the proposed biosensor. Here, a numerical model for the C-erbB-2 interface charge equivalent is also developed. The analysis of device sensitivity in both saliva and serum environments for various C-erbB-2 concentrations has been carried out. Our study reveals that III-V In1-xGaxAs/Si heterojunction with x composition of 0.2 and extended gate geometry provides an increased tunneling probability, improves the gate control to get a higher ION/IOFF ratio and higher sensitivity. In addition to this, the impact of interface charges corresponding to the different amounts of C-erbB-2 biomarkers on the biosensor sensitivity (in terms of ION/IOFF ratio) yields higher sensitivity of the order of 106.

Hawking radiation from a Reissner-Nordstrom-AdS black hole with integral monopoles in extended phase space

In recent years, thermodynamics and phase transitions of black holes in extended phase space have been extensively studied. The results show that the original first law of thermodynamics needs revising and new phase transitions will appear. However, so far, Hawking tunneling radiation has not been widely studied in the extended phase space. In particular, whether the tunneling radiation probability changes at this time is still uncertain. This work focuses on this topic, that is, to calculate the specific value of the tunneling probability in the extended phase space and ascertains whether the results obtained in the normal phase space are consistent with those in the extended phase space. The methods used herein are described below. Taking Reissner-Nordstrom-AdS black holes with global monopole for example, the cosmological parameters are regarded as dynamic variables, which is different from previous treatment methods that regard them as constants and ignore their contributions to the tunneling probability. In particular, cosmological parameters are introduced and regarded as thermodynamic pressure when the tunneling probability is calculated, and their contribution to the tunneling probability is considered. In the work the tunneling process of mass particles is mainly studied. The outgoing particles are viewed as spherical de Broglie waves, and then the relative phase velocity and group velocity are calculated. The geodesic equation is obtained according to the relationship between the two velocities, and the tunneling probability is calculated from the geodesic equation. It is concluded that the results show that the tunneling probability of the ingoing particles is proportional to the difference in the Bekenstein-Hawking entropy of the black hole before and after the particles tunnel, and the radiation spectrum deviates from the pure thermal spectrum, which is exactly the same as the case that the cosmological parameters are treated as constants. This means that the tunneling probability of particles can be obtained in the extended phase space, and the tunneling process does not depend on thermodynamic parameters. In addition, it is found that although the global monopole affects the dynamical behavior and thermodynamic quantity of the particle, it does not affect the entropy change or tunneling rate. In other words, the conclusion that the tunneling probability in extended phase space is exactly the same as that in normal phase space does not depend on the space-time topology.

Quantum dynamics calculations on isotope effects of hydrogen transfer isomerization in formic acid dimer

We present a quantum dynamics study on the isotope effects of hydrogen transfer isomerization in the formic acid dimer, and this is achieved by multidimensional dynamics calculations with an efficient quantum mechanical theoretical scheme developed by our group, on a full-dimensional neural network ab initio potential energy surface. The ground-state and fundamental tunneling splittings for four deuterium isotopologues of formic acid dimer are considered, and the calculated results are in very good general agreement with the available experimental measurements. Strong isotope effects are revealed, the mode-specific fundamental excitation effects on the tunneling rate are evidently influenced by the deuterium substitution of H atom with the substitution on the OH bond being more effective than on the CH bond. Our studies are helpful for acquiring a better understanding of isotope effects in the double-hydrogen transfer processes.

Spin-state energetics and magnetic anisotropy in penta-coordinated Fe(III) complexes with different axial and equatorial ligand environments.

The penta-coordinated trigonal-bi-pyramidal (TBP) Fe(III) complex (PMe2Ph)2FeCl3 shows a reduced magnetic anisotropy in its intermediate-spin (IS) state as compared to its methyl-analog (PMe3)2Fe(III)Cl3. In this work, the ligand environment in (PMe2Ph)2FeCl3 is systematically altered by replacing the axial -P with -N and -As, the equatorial -Cl with other halides, and the axial methyl group with an acetyl group. This has resulted in a series of Fe(III) TBP complexes modelled in their IS and high-spin (HS) states. Lighter ligands -N and -F stabilize the complex in the HS state, while the magnetically anisotropic IS state is stabilized by -P and -As at the axial site, and -Cl, -Br, and -I at the equatorial site. Larger magnetic anisotropies appear for complexes with nearly degenerate ground electronic states that are well separated from the higher excited states. This requirement, largely controlled by the d-orbital splitting pattern due to the changing ligand field, is achieved with a certain combination of axial and equatorial ligands, such as -P and -Br, -As and -Br, and -As and -I. In most cases, the acetyl group at the axial site enhances the magnetic anisotropy compared to its methyl counterpart. In contrast, the presence of -I at the equatorial site compromises the uniaxial type of anisotropy of the Fe(III) complex leading to an enhanced rate of quantum tunneling of magnetization.

Design and Parametric Analysis of Charge Plasma Junctionless TFET for Biosensor Applications

This paper presents a new design of charge plasma junctionless tunnel field effect transistor (CP JLTFET) with improved ON current, surface potentials. For the ease of fabrication, source and drain regions are induced in intrinsic silicon material using proper metal workfunctions. The rate of tunneling of electrons is found more in case of proposed CP JLTFET. The cavity length is varied between 8 nm and 10 nm and different dielectric constants have been used. This increased the ON state performance of device i.e ON drive current, potential and electric field. The increase in tunneling of electrons is mainly due to high recombination of carriers in the channel region. The proposed device simulated their electrical parameters like drain current, surface potentials, electric field, and energy bands with different dielectric constants. These excellent performance parameters of the proposed device with an appropriate material can be used for sensing application of biomolecules by introducing a cavity in the device.

Long-range hydrogen-bond relay catalyses the excited-state proton transfer reaction.

Solvent (e.g., water)-catalyzed proton transfer (SCPT) via the relay of hydrogen (H)-bonds plays a key role in proton migration. In this study, a new class of 1H-pyrrolo[3,2-g]quinolines (PyrQs) and their derivatives were synthesized, with sufficient separation of the pyrrolic proton donating and pyridinic proton accepting sites to probe excited-state SCPT. There was dual fluorescence for all PyrQs in methanol, i.e., normal (PyrQ) and tautomer 8H-pyrrolo[3,2-g]quinoline (8H-PyrQ) emissions. The fluorescence dynamics unveiled a precursor (PyrQ) and successor (8H-PyrQ) relationship and the correlation of an increasing overall excited-state SCPT rate (kSCPT) upon increasing the N(8)-site basicity. kSCPT can be expressed by the coupling reaction kSCPT = Keq × kPT, where kPT denotes the intrinsic proton tunneling rate in the relay and Keq denotes the pre-equilibrium between randomly and cyclically H-bonded solvated PyrQs. Molecular dynamics (MD) simulation defined the cyclic PyrQs and analyzed the H-bond and molecular arrangement over time, which showed the cyclic PyrQs incorporating ≧3 methanol molecules. These cyclic H-bonded PyrQs are endowed with a relay-like proton transfer rate, kPT. MD simulation estimated an upper-limited Keq value of 0.02-0.03 for all studied PyrQs. When there was little change in Keq, the distinct kSCPT values for PyrQs were at different kPT values, which increased as the N(8) basicity increased, which was induced by the C(3)-substituent. kSCPT was subject to a deuterium isotope effect, where the kSCPT of 1.35 × 1010 s-1 for PyrQ-D in CH3OD was 1.68 times slower than that (2.27 × 1010 s-1) of PyrQ in CH3OH. MD simulation provided a similar Keq for PyrQ and PyrQ-D, leading to different proton tunneling rates (kPT) between PyrQ and PyrQ-D.

Thermoelectric transport properties of single quantum dot systems in the presence of Majorana states

We present theoretical results for the thermoelectric transport properties in a single quantum dot system side coupled to a Majorana nanowire. The system’s electrical conductivity G , and the fundamental thermoelectric parameters such as the Seebeck coefficient S and thermal conductivity κ are numerically estimated based on a linear response approximation. Our results prove that the Majorana states in the side nanowire play an important role in the system’s thermoelectric response. In particular, a proper choice of the quantum dot — Majorana nanowire tunneling rate ξ and of the Majorana states overlap amplitude ɛ M can provide the appropriate physical environment for the experimental detection of Majorana states via thermoelectrical experimental measurements. • We considered the effects of Majorana states on the thermoelectric response of a single quantum dot system. • We present numerical results for the system electrical conductivity, Seebeck coefficient, thermal conductivity, and figure of merit. • The system thermoelectric response is strongly dependent on the quantum dot — Majorana nanowire tunneling rate ξ and of the Majorana states overlap amplitude ɛ M .

Design and Performance Assessment of Split Gate Dielectric Modulated Junction less TFET Variation of Hfo2 by the Divided Gate Insulator for High Sensitivity Using Tcad Simulation

A number of more recent discoveries in microbiology have made reliable identification of nano-biomolecules and extensive analyses of them necessary. A variety of proteins, including DNA, biotin-streptavidin, amino acids, as well as many types of bacteria and viruses, must be found and analyzed in order to fully comprehend any odd behavior occurring inside of live cells. Rapid testing and detection are essential steps in preventing undiscovered biohazards from eradicating the human race and other terrestrial living things. Since many decades ago, developing an accurate, affordable biosensor has been a struggle for scientists [1]. When compared to pricey laboratory-based sensors and detection methods, FET-based lab-on-chip nano biosensors appear to be a promising substitute. It is significantly more dependable than conventional bulk sensors because of its size, affordability, low power consumption, resilience, faster response time, and better sensitivity [1]. Due to their precision, adaptability, and compatibility with embedded systems, dielectrically modulated FET biosensors with Nano cavities are emerging as a promising research area that can yield useful data on bio-analyses. As an alternative to conventionally doped TFET devices, using a charge plasma SiGe-heterojunction double gate TFET, a label-free biosensor can be produced, bypassing the need for conventional semiconductors, which require a large thermal budget and are susceptible to random dopant fluctuations (RDFs). The effect of changing the dielectric constant (k), the positive and negative charge density, the gate work function, and the cavity size has been investigated to better understand how these factors affect the performance of the proposed biosensor. These parameters modify the biosensor's electric characteristics, improving detection [2]. There is also discussion of how these factors influence the device's drain current, electric field, surface potential, sub-threshold swing (SS), insulator-to-metal film (ION/IOFF) ratio, and electron tunneling rate (ETR). The sensitivity of the drain current in the proposed biosensor is also investigated. There is no restriction on whether or whether the proposed structure is used for charged or neutral molecules.Under lower supply voltages, it is discovered that the SG-DM current JLFET's sensitivity is high, measuring 1.2 *10^3, with a potential sensitivity of 1.4 V. A result, the SG-DM [2] JLFET exhibits good application potential while consuming little power and having ahigh sensitivity.

Gravitational orbits, double-twist mirage, and many-body scars

We explore the implications of stable gravitational orbits around an AdS black hole for the boundary conformal field theory. The orbits are long-lived states that eventually decay due to gravitational radiation and tunneling. They appear as narrow resonances in the heavy-light OPE when the spectrum becomes effectively continuous due to the presence of the black hole horizon. Alternatively, they can be identified with quasi-normal modes with small imaginary part in the thermal two-point function. The two pictures are related via the eigenstate thermalisation hypothesis. When the decay effects can be neglected the orbits appear as a discrete family of double-twist operators. We investigate the connection between orbits, quasi-normal modes, and double-twist operators in detail. Using the corrected Bohr-Sommerfeld formula for quasi-normal modes, we compute the anomalous dimension of double-twist operators. We compare our results to the prediction of the light-cone bootstrap, finding perfect agreement where the results overlap. We also compute the orbit decay time due to scalar radiation and compare it to the tunneling rate. Perturbatively in spin, in the light-cone bootstrap framework double-twist operators appear as a small fraction of the Hilbert space which violate the eigenstate thermalization hypothesis, a phenomenon known as many-body scars. Nonperturbatively in spin, the double-twist operators become long-lived states that eventually thermalize. We briefly discuss the connection between perturbative scars in holographic theories and known examples of scars in the condensed matter literature.

πσ*-Mediated Nonadiabatic Tunneling Dynamics of Thiophenols in S1: The Semiclassical Approaches.

The S-H bond tunneling predissociation dynamics of thiophenol and its ortho-substituted derivatives (2-fluorothiophenol, 2-methoxythiophenol, and 2-chlorothiphenol) in S1 (ππ*) where the H atom tunneling is mediated by the nearby S2 (πσ*) state (which is repulsive along the S-H bond extension coordinate) have been investigated in a state-specific way using the picosecond time-resolved pump-probe spectroscopy for the jet-cooled molecules. The effects of the specific vibrational mode excitations and the SH/SD substitutions on the S-H(D) bond rupture tunneling dynamics have been interrogated, giving deep insights into the multidimensional aspects of the S1/S2 conical intersection, which also shapes the underlying adiabatic tunneling potential energy surfaces (PESs). The semiclassical tunneling rate calculations based on the Wentzel-Kramers-Brillouin (WKB) approximation or Zhu-Nakamura (ZN) theory have been carried out based on the ab initio PESs calculated in the (one, two, or three) reduced dimensions to be compared with the experiment. Though the quantitative experimental results could not be reproduced satisfactorily by the present calculations, the qualitative trends among different molecules in terms of the behavior of the tunneling rate versus the (adiabatic) barrier height or the number of PES dimensions could be rationalized. Most interestingly, the H/D kinetic isotope effect observed in the tunneling rate could be much better explained by the ZN theory compared to the WKB approximation, indicating that the nonadiabatic coupling matrix elements should be invoked for understanding the tunneling dynamics taking place in the proximity of the conical intersection.

Design optimization of a silicon-germanium heterojunction negative capacitance gate-all-around tunneling field effect transistor based on a simulation study

The steep sub-threshold swing of a tunneling field-effect transistor (TFET) makes it one of the best candidates for low-power nanometer devices. However, the low driving capability of TFETs prevents their application in integrated circuits. In this study, an innovative gate-all-around (GAA) TFET, which represents a negative capacitance GAA gate-to-source overlap TFET (NCGAA-SOL-TFET), is proposed to increase the driving current. The proposed NCGAA-SOL-TFET is developed based on technology computer-aided design (TCAD) simulations. The proposed structure can solve the problem of the insufficient driving capability of conventional TFETs and is suitable for sub-3-nm nodes. In addition, due to the negative capacitance effect, the surface potential of the channel can be amplified, thus enhancing the driving current. The gate-to-source overlap (SOL) technique is used for the first time in an NCGAA-TFET to increase the band-to-band tunneling rate and tunneling area at the silicon–germanium heterojunction. By optimizing the design of the proposed structure via adjusting the SOL length and the ferroelectric layer thickness, a sufficiently large on-state current of 17.20 μA can be achieved and the threshold voltage can be reduced to 0.31 V with a sub-threshold swing of 44.98 mV/decade. Finally, the proposed NCGAA-SOL-TFET can overcome the Boltzmann limit-related problem, achieving a driving current that is comparable to that of the traditional complementary metal–oxide semiconductor devices.

Logarithm corrections and thermodynamics for Horndeski gravity like black holes

In this paper, we compute the Hawking temperature by applying quantum tunneling approach for the Horndeski like black holes. We utilize the semi-classical phenomenon and WKB approximation to the Lagrangian field equation involving generalized uncertainty principle (GUP) and compute the tunneling rate as well as Hawking temperature. For the zero gravity parameter, we obtain results consistent without correction parameter or original tunneling. Moreover, we study the thermal fluctuations of the considered geometry and examine the stable state of the system by heat capacity technique. We also investigate the behavior of thermodynamic quantities under the influence of thermal fluctuations. We observe from the graphical analysis, the corresponding system is thermodynamically stable with these correction terms.

On the influence of Maxwell-Chern-Simons electrodynamics in nuclear fusion involving electronic and muonic molecules

New results recently obtained (Caruso F. et al., Ann. Phys. (N.Y.), 443 (2022) 168943). established some non-relativistic ground state solutions for three-body molecules interacting through a Chern-Simons model. Within this model, it was argued that the Chern-Simons potential should not help improve the fusion rates by replacing electrons with muons, in the case of particular muonic molecules. This achievement motivated us to investigate quantitatively whether or not the Maxwell-Chern-Simons electrodynamics could influence positively, for example, the probability of having a muon-catalyzed fusion; its contribution to electronic molecules is also considered in this letter. The principal factors related to the probability of elementary nuclear fusion are therefore numerically calculated and compared with their analogs admitting other forms of interaction like −1/ρ and ln(ρ). The analysis carried on here confirms that one should not expect a significant improvement in nuclear fusion rates in the case of muonic molecules, although, surprisingly, the same is not true for electronic molecules, compared with other theoretical predictions. Numerical predictions for the fusion rates for ppe, pp μ, dde and dd μ molecules are given as well as the predicted value for the tunneling rate for these molecules.

Design and Investigation of a Novel Gate-All-Around Vertical Tunnel FET with Improved DC and Analog/RF Parameters

In this paper, a novel structure of gate-all-around vertical TFET (GAA-VTFET) is proposed and investigated for the first time with the help of 3D TCAD simulator. It is found that GAA-VTFET offers much improvement in various DC parameters like ION, IOFF, subthreshold swing (SSAVG), and turn-on voltage (VT) as compared with the conventional GAA-TFET. As the tunneling direction of charge carriers is in parallel to the gate electric field, channel thickness in GAA-VTFET is rigorously reduced without compromising with the tunneling area and thus, improving the tunneling rate at source/channel interface during ON-state. Further, subthreshold leakage of the charge carriers is significantly reduced due to deployment of a dielectric layer beneath channel/drain interface extending up to source region. The impact of variation in geometric dimensions is also analysed to obtain the optimum performance of the proposed device. The current-switching ratio (ION/IOFF) is observed to be in order of ∼1013 while SSAVG of 56 mV decade−1 is achieved in the proposed device. Moreover, analog/RF parameters are also analysed in this work and it is noticed that an improved cut-off frequency of 593 GHz can be achieved due to reduced parasitic capacitances along with improved transconductance in GAA-VTFET. Next, the proper benchmarking reveals that GAA-VTFET offers better ION/IOFF, VT, and SSAVG as compared with the similar devices. Finally, based on the transient analysis of inverter circuit, the proposed GAA-VTFET is found to be more suitable for digital applications as it offers less rise-time along with full-voltage swing.