Analytical Potential Model Research Articles

Surface Potential Analysis of Dual Material Gate Silicon-Based Ferroelectric TFET for Biosensing Application

By means of a dielectric modulation method, this research offers the first ever 2D analytical model for the surface potential of a dual material gate Ferroelectric-TFET (DMG-Fe-TFET) device used in an enzyme-free biosensor. Compared to a device with a single material gate, the sensitivity of a device with a gate made of two distinct metals (M1-M2) is improved by an increase in tunnelling width at the secondary tunnelling junction. This model accounts for the change in surface potential caused by varying the value, position, and fill factor of the target biomolecules. Several distinct device architectures are used to enhance the efficiency of the envisaged Fe-TFET in the nanoscale range. We also investigated how the dimensions of the Nano cavity and other parts of the device affect its sensitivity. In addition, simulation findings using the SILVACO Atlas platform are used to confirm the results obtained when testing the DMG Fe-TFET’s sensitivity in comparison to other recently manufactured FETs.

XUV Rectification Effect in the IR-Dressed Medium.

We show that the quasistatic dipole moment can be induced by a short extreme ultraviolet (XUV) pulse (XUV rectification effect) in atomic gas medium subjected to an intense infrared (IR) field (IR-dressed atoms). The general theory of the XUV rectification effect for a single IR-dressed atom is presented, which explicitly relates IR-modified polarizability of an atomic system in the XUV range with the induced quasistatic dipole moment. We illustrate general properties of the XUV rectification effect in an atomic system within the analytical zero-range potential model by presenting the dependence on the IR-field intensity and the time delay between XUV and IR pulses.

A Surface Potential Model for Metal-Oxide-Semiconductor Transistors Operating near the Threshold Voltage

Device physics and accurate transistor modeling are necessary to reduce the operating voltage near the threshold for power-constrained circuits. Conventional device modeling for metal-oxide-semiconductor (MOS) transistors focuses on operations in either strong or weak inversion regimes, and the electrostatics at gate biases near the threshold voltage is rarely studied. This research proposed an analytical model to describe the distribution of the surface potential along the channel for near-threshold operation. Numerical device simulations were also performed to investigate the electrostatics near the threshold voltage. The numerical simulation with constant carrier mobility showed an overshoot in the transconductance due to decay of the lateral electric field with gate bias. The decay of the lateral electric field was predicted by the proposed analytical surface potential model which considered widening the channel length with flooding of the inversion carriers in the channel and gate overlap regions. The channel length widening effect saturated as the gate bias further increased. Therefore, evident transconductance overshoot was observed near the threshold voltage in short-channel devices.

Physics based numerical model of a nanoscale dielectric modulated step graded germanium source biotube FET sensor: modelling and simulation

This paper proposes a novel dielectric modulated step-graded germanium source biotube FET for label-free biosensing applications. Its integrated structure and unique design combine the benefits of the gate stack, germanium source, triple-gate architecture, and a step-graded biotube channel, resulting in superior performance over existing biosensors. A compact two-dimensional analytical model for channel potential, drain current, threshold voltage, and subthreshold swing has been formulated and agrees well with the simulated results. The comprehensive investigation of different device parameters, including doping and bias, offers valuable insights into optimizing the biosensor’s performance. The proposed biosensor exhibits remarkable sensitivity, achieving up to 263 mV and 1495.52 nA for certain biomolecules, which has been validated by a compact analytical model and simulations performed on the SILVACO TCAD simulator. Several parameters are employed to assess the biosensor’s effectiveness: threshold voltage, ION/IOFF ratio, subthreshold swing, off-current, peak trans-conductance, and on-current. Furthermore, the biotube channel design enables lightweight and cost-efficient biosensors, enhancing the biosensor’s practicality. This work also includes an analysis of the effect of temperature on the biosensor’s performance and characteristics, providing insights into practical applications. High sensitivity of the biosensor signifies a significant advancement in biosensing technology, suggesting a wide range of potential applications in biomedical field.

An analytical model for the energy storage potential of phase change materials supported by polymeric colloidal aerogels

Effective thermal energy storage has become one of the well-recognized aspects of modern energy management. Phase change materials (PCMs) shape-stabilized in the porous structure of porous support materials are one of the candidates to reach stable and effective thermal energy storage. This study presents an analytical model for the prediction of thermal energy storage density and thermal conductivity of colloidal aerogels impregnated by a PCM (TCAP model). The TCAP model is a series-parallel model that combines the thermal conductivity of the structure of the supporting aerogel and the thermal characteristics of the impregnated PCM. To validate the model, a mesoporous resorcinol-formaldehyde aerogel with an average pore diameter of 5.2 nm is synthesized, and two types of polyethylene glycol PCMs (PEG600 and PEG2000) are impregnated into the porous structure of the supporting material. The results confirm that the TCAP model can accurately predict the thermal energy storage characteristics of the system in terms of energy storage rate and density. Based on parametric studies, the highest heat capacity that can be achieved in a resorcinol-formaldehyde aerogel/polyethylene glycol is 35 kJ/kg.k with a ΔT of 40 K. On the other hand, it can be predicted that when ΔT increases from 10 K to 20 K, the energy storage of the system will change in the range of 52 % to 74 %. Moreover, The TCAP model developed in this study can be used to design/optimize energy storage materials for various applications such as smart buildings, solar energy storage devices, environmental thermal management systems, wearable thermal management devices, and temperature control in electronics.

An accurate analytical surface potential model of heterojunction tunnel FET

Based on the accurate and efficient thermal injection method, we develop a fully analytical surface potential model for the heterojunction tunnel field-effect transistor (H-TFET). This model accounts for both the effects of source depletion and inversion charge, which are the key factors influencing the charge, capacitance and current in H-TFET. The accuracy of the model is validated against TCAD simulation and is greatly improved in comparison with the conventional model based on Maxwell–Boltzmann approximation. Furthermore, the dependences of the surface potential and electric field on biases are well predicted and thoroughly analyzed.

Simultaneous electrostatic trapping of merged cation & anion beams.

Simultaneous trapping of merged cation and anion beams in the hybrid electrostatic ion beam trap (HEIBT) opens new opportunities for the study of the interactions of isolated atomic molecular or cluster ions with oppositely charged ionic species. Application of the trapped merged beams requires a detailed understanding of the trapping dynamics and the effect of the Coulombic attractive and repulsive forces between the ions on their motion in the trap. The simultaneous trapping regime is explored experimentally for SF6- anion and SF5+ cation beams and compared to realistic ion trajectory simulations. The respective stability of the simultaneously trapped cation and anion beams is experimentally tracked by nondestructive and mass sensitive image charge monitoring. An approximate analytical potential model is presented for modeling the dynamics of trapped ions, providing insight into the role of ion-ion interactions, and suggesting a simplified mirror design.

Analytical approximation of surface potential and analysis of C–V characteristics of bulk MOSFETs at cryogenic temperatures

In this paper, we present an accurate analytical approximation of the surface potential for bulk MOSFETs, starting from its transcendental relation with respect to the gate voltage, valid from room temperature to deep cryogenic temperatures, encompassing the entire operating region. The results obtained from the proposed analytical model for the surface potential have very high accuracy, with the maximum absolute error of the order of nanovolts, when compared with the results of numerical calculations. We also investigate and present the temperature dependence of the semiconductor charge density and its physical implications on the C–V characteristics. A kink is observed in the C–V characteristics near flatband, due to dopant freeze-out at cryogenic temperatures. We have also been able to develop a model for the C–V characteristics, that captures this kink accurately, over a wide temperature range. The results obtained from this model are compared with both TCAD simulations as well as with experimental data, and the match is found to be excellent.

Physics-based 2D analytical potential model with disorder effects for scaling a-IGZO TFT via dual material gate engineering

A dual material gate (DMG) amorphous indium gallium zinc oxide (a-IGZO) thin-film transistor (TFT) is proposed, which has a gate structure of lateral-contact-metals with two work functions. In view of multiple gate materials and localized/delocalized states, the potential calculations using Poisson’s equation are complicated and without analytical solution, which complicates the gate controllability analysis and future compact modeling methodology. Therefore, we have developed an analytical 2D potential model, that shows a great agreement with the numerical solution, taking into account asymmetry effects and scaling behavior. It can be used to tune potential or electric-field profiles by DMG engineering, increase the average channel electric-field, reduce the electric-field at the Drain side, and thus improve the performance of short-channel a-IGZO TFT with immunity to drain-induced-barrier-lowing (DIBL) and hot carrier effect (HCE).

Wearable Piezoelectric Energy Harvesting From Human Gait: Modeling and Experimental Validation

Wearable devices with a flexible and stretchable form factor enable novel and attractive applications. The promising outlook for these devices is hindered by their limited battery capacity constrained by size and other physical limitations. Motion energy harvesting can alleviate these challenges and reduce dependency on batteries. Despite this potential, a definitive capacity for wearable motion energy harvesting has yet to be identified. To facilitate the exploration of this capacity, we propose an analytical model for the energy harvesting potential of a wearable piezoelectric energy harvester placed on the knee joint. In addition, we validate the proposed model extensively with a prototype piezoelectric energy harvester. Our results show that the proposed model estimates the harvested power with less than 5% mean absolute percentage error for all gait speeds and various transducer configurations. In addition, the proposed harvester can generate 161 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu \text{W}$ </tex-math></inline-formula> power at 5 mph. We further show that this amount can sustain a 35 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu \text{A}$ </tex-math></inline-formula> load.

Analytical modelling for surface potential of dual material gate overlapped-on-drain TFET(DM-DMG-TFET) for label-free biosensing application

This article presented the first-ever 2D analytical model for the surface potential of dual material gate overlapped-on-drain TFET (DMG-TFET) device for label-free biosensor application using dielectric modulation technique. The use of two different metal work functions for the gate (ϕM1<ϕM2) impacts the device’s surface potential to increase tunneling width at the secondary tunneling junction to enhance the device sensitivity compared to single material gate device. This model takes into account the effect of changing the dielectric constant value, location, and percentage of fill factor of the target biomolecules on the surface potential of the device. The parabolic approximation of surface potential is used for solving the 2D-Poisson’s equation by applying suitable boundary conditions. The analytical surface potential results are verified with the simulation result using the SILVACO Atlas tool.

A comprehensive physics based surface potential and drain current model for SiGe channel dual programmable FETs

In the present work, a comprehensive analytical model for surface potential and drain current has been developed for double gate silicon-germanium channel dual programmable FETs (SiGe-DP-FET) which is capable to conduct both in n- as well as p-modes. The developed model accurately predicts the impact of mole fraction (m) variation in Si(1 − m)Ge m channel on various device characteristics such as energy band, surface potential, electric field, drain current, and transconductance. While deriving the surface potential expression, the active SiGe channel is bifurcated in three regions such that regions I and III denote the two gated regions while region II denotes the ungated region. Further, in order to compute the expression for surface potential, 2D Poisson’s equation has been solved in gated regions while linear approximation has been applied in ungated region and subsequently, the drain current expression has been obtained by integrating the band-to-band generation rate of charge carriers across the source side Schottky junctions. Moreover, in order to validate the proposed model, the analytical results are compared and verified with 2D TCAD ATLAS simulated results and it has been observed that the results obtained using proposed model match well with the simulated results.

Theoretical study on potential energy surface and bound states of the Kr-CNCN complex: Compared with the Kr-NCCN system

The first ab initio potential energy surface of the Kr-CNCN system is investigated using the single double excitation coupled-cluster theory with noniterative treatment of triple excitation. The mixed basis sets are used with aug-cc-pVTz for the C and N atoms and aug-cc-pVTz-pp for the Kr atom, including an additional midbond function of 3s3p2d1f1g. The computed single point energies at 585 configurations are fitted to an analytical potential model. The potential energy surface of the Kr-CNCN complex has a nearly T-shaped global minimum with the energy of −286.6 cm−1 located at R = 6.88 a0, θ = 89.3°. The interaction of the linear CNCNKr geometry is stronger than that of the linear KrCNCN structure. The whole potential energy surface of the Kr-CNCN presents angular anisotropy. The bound state energies up to J = 9 and the wave functions are calculated by analytically solving the Schrödinger equation based on the ab initio potential energy surface. The calculated fundamental frequencies of bending vibration and stretching vibration of the Kr-CNCN are 24.0 cm−1 and 32.7 cm−1, respectively. The transition frequencies and the spectroscopic constants of the Kr-CNCN system are predicted, and the relevant results are compared with the Kr-NCCN complex. The differences in the PES and bound state energy levels between the Kr-CNCN and Kr-NCCN complexes are clarified. These results will help to further explore the formation causes of CN radical in the interstellar medium and provide a theoretical basis for future experimental spectra research of the Kr-CNCN system.

A New Surface Potential-Based Analytical Model for MFIS NCFETs

In this article, we present an analytical model for the surface potential ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\psi _{s}$ </tex-math></inline-formula> ) for metal–ferroelectric–insulator–semiconductor (MFIS) negative capacitance field-effect transistors (NCFETs) as a function of the gate voltage, by first developing the models regionwise (weak and strong inversion) and then merging them together in the moderate-inversion region by using a smoothing function. This model for <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\psi _{s}$ </tex-math></inline-formula> is used subsequently to obtain the charge and capacitance behavior and eventually to the development of the current–voltage model. It considers various important technology parameters, i.e., substrate doping, ferroelectric (FE) and oxide thicknesses, remnant polarization, and coercive field. All the model results showed an excellent match with those obtained from TCAD simulations. It has also been observed that capacitance matching, and thus, gate control, improves with an increase in the FE thickness and the ratio of the coercive field to remnant polarization, which can be utilized effectively in device and circuit designs for low-power applications. The small-signal parameters, extracted from the current–voltage characteristics, show the first-order continuity, thus making the model suitable for circuit simulation.

On the Log-Linear Inversion-Charge Relation for MOSFET Modeling

In this brief, we take a close look at the log-linear inversion-charge relation adopted in several charge-based compact models for MOSFETs. It is shown that the log-linear relation lacks flexibility in fitting the subthreshold characteristics independent of the above threshold behavior. The shortcomings are born out in specific examples comparing the <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${Q}_{\text {i}}$ </tex-math></inline-formula> – <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${V}_{\text {gs}}$ </tex-math></inline-formula> curves of the log-linear inversion-charge relation to those of the charge-sheet model and the analytic potential model for double-gate (DG) MOSFETs.

Analytical modeling and simulation of a triple metal vertical TFET with hetero-junction gate stack

In this paper, a new 2D analytical model for surface potential of a gate stacked triple metal Vertical TFET with n + delta doped layer (δ-doped n + SiGe GS-TMG-VTFET) is presented. The parabolic approximation process is used to solve the Poisson equation in terms of channel surface potential and electrical field respectively. The proposed method consists of a dual modulation effect that controls the surface potential at both the interface of the source and drains with the channel. This structure comprises SiO2 and HfO2 as gate-stacked materials to extend the control of the gate terminal over the channel. In addition, the proposed TMG-VTFET outperforms the surface potential results in terms of input and output characteristics like gate-source voltage (VGS) and drain-source voltage (VDS), gate oxide, and SiGe mole fraction. Finally, we obtained the expression of the channel surface potential, which involves the biasing variation of source and drain terminal. Our proposed model is accounting the variable of kane model in respect to extract the drain current characteristics. It can be modeled by integrating band-to-band tunneling generation rate using suitable boundary conditions. Now, efficiency of the proposed model for both the surface potential and drain current has been confirmed by comparing its analytical outcomes with the TCAD results.

A Surface Potential Model for Field-Effect Transistors With Bound-Charge Engineering

Semiconductor doping is limited by such practical concerns as bandgap narrowing and solid solubility limits of dopants. Bound-charge engineering (BCE) bypasses these limits by doping with surface bound charge located on the interface between a semiconductor and an adjacent low-permittivity oxide; it can be used to reduce depletion lengths of junctions in field-effect transistors (FETs). BCE is established by basic electrostatics and is widely applicable to emerging materials and novel devices. In this work, an analytical surface potential model for gate-all-around BCE-assisted silicon nanowire FETs, with arbitrary and possibly distinct spacer and gate oxides, is derived. This model is based on scaling theory and verified against atomistic quantum transport simulations; it provides an intuitive formalism for developing and modeling devices with BCE.

Performance Improvement of Nanoscale Field Effect Diode (FED) with Modified Charge Channel: 2D Simulation and an Analytical Surface Potential Model

Performance Improvement of Nanoscale Field Effect Diode (FED) with Modified Charge Channel: 2D Simulation and an Analytical Surface Potential Model

Analytical 3D Surface Potential Model of a Junction-Based Triple-Gate MOSFET Device

In this paper, a 3D potential model for a triple-gate Si MOSFET is derived in weak inversion using the variable separation technique based on a perimeter weighted approach. The channel potential is solved from Poisson’s equation along two different planes of the device separately and then using the same variable separation technique and proper boundary conditions 3D potential is addressed. Hence, the solution is not directly obtained from 3D Poisson's equation and does not involve any complex computation. The I-V model of the device is then predicted using the drift-diffusion technique. The accuracy of the model is checked with respect to commercial TCAD simulation results, and good agreement is observed. Our proposed model considers short-channel effects but does not find any quantum mechanical effects. The model result has also been compared with the industry-standard model to validate its performance. Due to its good accuracy, the model can be potentially invoked into a numerical simulator to predict the device's electrical behavior.

Analytical modelling and simulation of negative capacitance junctionless FinFET considering fringing field effects

Abstract This article proposes an analytical model for channel potential and threshold voltage for negative capacitance junctionless FinFET (NC-JL FinFET). The Poisson's equation has been solved in collaboration with Landau–Khalatnikov equation to obtain analytical model for electrostatic potential distribution, threshold voltage and DIBL. The effect of fringing field on the potential distribution function due to source/drain spacer has also been taken into consideration. The results of proposed models are also validated and compared with simulated results of Sentaurus TCAD device simulator. The effect of various physical parameters like thickness of ferroelectric layer, fin thickness, spacer length, gate dielectric constant etc. on the performance of device has been studied. Further, the performance is also examined for different technology nodes and its (in context of) SCEs.