Simulation Of Electronic Devices Research Articles

Multi-scale simulations of two dimensional material based devices: the NanoTCAD ViDES suite

NanoTCAD ViDES (Versatile DEvice Simulator) is an open-source suite of computing codes aimed at assessing the operation and the performance of nanoelectronic devices. It has served the computational nanoelectronic community for almost two decades and it is freely available to researchers around the world in its website (http://vides.nanotcad.com), being employed in hundreds of works by many electronic device simulation groups worldwide. We revise the code structure and its main modules and we present the new features directed towards (i) multi-scale approaches exploiting ab-initio electron-structure calculations, aiming at the exploitation of new physics in electronic devices, (ii) the inclusion of arbitrary heterostructures of layered materials to devise original device architectures and operation, and (iii) the exploration of novel low-cost, green technologies in the mesoscopic scale, as, e.g. printed electronics.

Design and comparative analysis of active-loaded differential amplifier using double-gate MOSFET

This research paper proposes the design of an active-loaded differential amplifier using the Double-Gate (DG) MOSFET. This differential amplifier employs feedback and simplifies a previously designed topology by reducing it to a single-ended output instead of a differential one. Other topologies have been referred to determine the benchmark of this design work. The DG MOSFET has been utilized for its high-frequency characteristics, Radio Frequency (RF) applications, and possible advantages in scalability. Electronic device simulation determines the technical feasibility of this differential amplifier using DG MOSFET. The designed differential amplifier exhibits a differential gain of 1.7–1.8 V/V and −3 dB cut-off frequency of 42 MHz. The amplifier can be used in various applications using this methodical design process and the circuital information.

Fully solution-processed InSnO/HfGdO X thin-film transistor for light-stimulated artificial synapse

In recent years, the research interest in brain-inspired light-stimulated artificial synaptic electronic devices has greatly increased, due to their great potential in constructing low-power, high-efficiency, and high-speed neuromorphic computing systems. However, in the field of electronic synaptic device simulation, the development of three-terminal synaptic transistors with low manufacturing cost and excellent memory function still faces huge challenges. Here, a fully solution-processed InSnO/HfGdO X thin film transistor (TFT) is fabricated by a simple and convenient solution process to verify the feasibility of light-stimulated artificial synapses. This experiment investigated the electrical and synaptic properties of the device under light stimulation conditions. The device successfully achieved some important synaptic properties, such as paired-pulse facilitation, excitatory postsynaptic current and the transition from short-term memory to long-term memory. In addition, the device also exhibits brain-like memory and learning behaviors under different colors of light stimulation. This work provides an important strategy for the realization of light-stimulated artificial synapses and may have good applications in the field of artificial neuromorphic computing by light signals in the future.

Multiscale modeling and simulation methods for electromagnetic and multiphysics problems

Multiscale modeling and simulation methods for electromagnetic and multiphysics problems

TCAD Modeling of Resistive-Switching of HfO2 Memristors: Efficient Device-Circuit Co-Design for Neuromorphic Systems

In neuromorphic computing, memristors (or “memory resistors”) have been primarily studied as key elements in artificial synapse implementations, where the memristor provides a variable weight with intrinsic long-term memory capabilities, based on its modifiable resistive-switching characteristics. Here, we demonstrate an efficient methodology for simulating resistive-switching of HfO2 memristors within Synopsys TCAD Sentaurus—a well established, versatile framework for electronic device simulation, visualization and modeling. Kinetic Monte Carlo is used to model the temporal dynamics of filament formation and rupture wherein additional band-to-trap electronic transitions are included to account for polaronic effects due to strong electron-lattice coupling in HfO2. The conductive filament is modeled as oxygen vacancies which behave as electron traps as opposed to ionized donors, consistent with recent experimental data showing p-type conductivity in HfOx films having high oxygen vacancy concentrations and ab-initio calculations showing the increased thermodynamic stability of neutral and charged oxygen vacancies under conditions of electron injection. Pulsed IV characteristics are obtained by inputting the dynamic state of the system—which consists of oxygen ions, unoccupied oxygen vacancies, and occupied oxygen vacancies at various positions—into Synopsis TCAD Sentaurus for quasi-static simulations. This allows direct visualization of filament electrostatics as well as the implementation of a nonlocal, trap-assisted-tunneling model to estimate current-voltage characteristics during switching. The model utilizes effective masses and work functions of the top and bottom electrodes as additional parameters influencing filament dynamics. Together, this approach can be used to provide valuable device- and circuit-level insight, such as forming voltage, resistance levels and success rates of programming operations, as we demonstrate.

Simulation of Electronic Quantum Devices: Failure of Semiclassical Models

To simplify the design and optimization of new-generation nanomaterials and related electronic and optoelectronic quantum devices, energy dissipation versus decoherence phenomena are often simulated via local models based on the Wigner-function formalism. Such a local description is, however, intrinsically incompatible with the fully quantum-mechanical (i.e., non-local) nature of the dissipation-free carrier dynamics. While the limitations of such hybrid treatments have already been pointed out in the past in diverse contexts, the spirit of the present work is to provide a more cohesive and critical review. To this aim, we focus on the fundamental link between the Wigner-function picture and the density-matrix formalism. In particular, we show that, starting from well-established density-matrix-based models, the resulting Wigner-function dissipation and/or thermalization dynamics is necessarily non-local. This leads to the conclusion that the use of local Wigner function models borrowed from the semiclassical Boltzmann theory is formally not justified and may produce unreliable results, and that such simplified local treatments should be replaced by fully non-local quantum models derived, e.g., via the density-matrix formalism.

Simulation of bipolar charge transport in graphene on h-BN

Purpose The purpose of this paper is to simulate charge transport in monolayer graphene on a substrate made of hexagonal boron nitride (h-BN). This choice is motivated by the fact that h-BN is one of the most promising substrates on account of the reduced degradation of the velocity due to the remote impurities. Design/methodology/approach The semiclassical Boltzmann equations for electrons in the monolayer graphene are numerically solved by an approach based on a discontinuous Galerkin (DG) method. Both the conduction and valence bands are included, and the inter-band scatterings are taken into account as well. Findings The importance of the inter-band scatterings is accurately evaluated for several values of the Fermi energy, addressing the issue related to the validity of neglecting the generation-recombination terms. It is found out that the inclusion of the inter-band scatterings produces sizable variations in the average values, like the current density, at zero Fermi energy, whereas, as expected, the effect of the inter-band scattering becomes negligible by increasing the absolute value of the Fermi energy. Research limitations/implications The correct evaluation of the influence of the inter-band scatterings on the electronic performances is deeply important not only from a theoretical point of view but also for the applications. In particular, it will be shown that the time necessary to reach the steady state is greatly affected by the inter-band scatterings, with not negligible consequences on the switching on/off processes of realistic devices. As a limitation of the present work, the proposed approach refers to the spatially homogeneous case. For the simulation of electron devices, non-homogenous numerical solutions are required. This last case will be tackled in a forthcoming paper. Originality/value As observed in Majorana et al. (2019), the use of a Direct Simulation Monte Carlo (DSMC) approach, which properly describes the inter-band scatterings, is computationally very expensive because the valence band is highly populated and a huge number of particles is needed. Even by simulating holes instead of electrons does not overcome the problem because there is a certain degree of ambiguity in the generation and recombination terms of electron-hole pairs. The DG approach, used in this paper, does not suffer from the previous drawbacks and requires a reasonable computing effort.

A Multiparticle Drift-Diffusion Model and its Application to Organic and Inorganic Electronic Device Simulation

In this paper, we present a novel generalized multiparticle drift-diffusion (mp-DD) model capable to overcome some limitations imposed by the classic drift-diffusion model by taking into account multiple carrier populations. We demonstrate the model's ability and flexibility in simulating systems from different application contexts. We conclude that the developed mp-DD model allows investigating a wide range of complex mechanisms, such as subband charge transport calculation or intersystem crossing (ISC), which are crucial for the understanding and design of organic and inorganic semiconductor devices largely employed for both photovoltaics and light emitting applications.

Time-dependent quantum Monte Carlo simulation of electron devices with two-dimensional Dirac materials: A genuine terahertz signature for graphene

An intrinsic electron injection model for linear band two-dimensional (2D) materials, like graphene, is presented and its coupling to a recently developed quantum time-dependent Monte Carlo simulator for electron devices, based on the use of stochastic Bohmian conditional wave functions, is explained. The simulator is able to capture the full (DC, AC, transient and noise) performance of 2D electron devices. In particular, we demonstrate that the injection of electrons with positive and negative kinetic energies is mandatory when investigating high frequency performance of linear band materials with Klein tunneling, while traditional models dealing with holes (defined as the lack of electrons) can lead to unphysical results. We show that the number of injected electrons is bias-dependent, implying that an extra charge is required to get self-consistent results. Interestingly, we provide a successful comparison with experimental DC data. Finally, we predict that a genuine high-frequency signature due to a roughly constant electron injection rate in 2D linear band electron devices (which is missing in 2D parabolic band ones) can be used as a band structure tester.

A PSPICE Fast Model for the Single Electron Transistor

Motivated by the merits of low power dissipation, ultra-small size, and high speed of many nanoelectronic devices, They have been demonstrated to ensure future progress. Single-electron devices became one of the most important nanoelectronic devices due to their interesting electrical characteristics and behavior. Many research efforts moved to describe their electrical characteristics to use them with conventional electronic devices. This paper deals with modeling and simulation of such new electronic devices. This paper presents a model for the Single Electron Transistor (SET) and its application in simulating hybrid SET/MOS ADC and DAC converters. This model uses the orthodox theory of single-electron tunneling and determines the average current through the transistor. The proposed model is more flexible that is valid for a large range of drain to source voltage, valid for single or multi-gate SET and symmetric or asymmetric SET. Finally, using this model with MOSFET transistors to realize multi-bit Analog-to-Digital Converters (ADC) and Digital-to-Analog Converters (DAC). The hybrid n-bit DAC nano-circuits are simulated for (n=4 and 8) using Orcad Capture PSPICE. The performance of the SET/MOS hybrid n-bit ADC circuits were simulated (for n=3 and 8). The results show that the transient operation of hybrid SET/MOS circuit-based DAC could successfully operate at 1000K while ADC could operate at 144K. This performance can be compared with the pure SET circuits, the proposed converter circuits have been enhanced in the drive capability and the power dissipation. Compared with the other SET/MOS hybrid circuit, the implemented converter circuits have low simulation time, high speed, high load drivability, and low power dissipation.

Modeling of Electron Devices Based on 2-D Materials

The advent of graphene and related 2-D materials has attracted the interest of the electron device research community in the past 14 years. The possibility to boost the transistor performance and the prospects to build novel device concepts with 2-D materials and their heterostructures has awakened a strong experimental interest that requires continuous support from modeling. In this paper, we review the state of the art in the simulation of electron devices based on 2-D materials. We outline the main methods to model the electronic bandstructure and to study electron transport, classifying them in terms of accuracy and computational cost. We briefly discuss, how they can be combined in a multiscale approach to provide a quantitative understanding of the mechanisms determining the operation of electron devices, and we examine the application of these methods to different families of 2-D materials. Finally, we shortly analyze the main open challenges of modeling 2-D-based electron devices.

Computational study of Fermi kinetics transport applied to large-signal RF device simulations

A detailed description and analysis of the Fermi kinetics transport (FKT) equations for simulating charge transport in semiconductor devices is presented. The fully coupled nonlinear discrete FKT equations are elaborated, as well as solution methods and work-flow for the simulation of RF electronic devices under large-signal conditions. The importance of full-wave electromagnetics is discussed in the context of high-speed device simulation, and the meshing requirements to integrate the full-wave solver with the transport equations are given in detail. The method includes full semiconductor band structure effects to capture the scattering details for the Boltzmann transport equation. The method is applied to high-speed gallium nitride devices. Finally, numerical convergence and stability examples provide insight into the mesh convergence behavior of the deterministic solver.

Multiscale Modeling of Photovoltaic Devices

Renewable energy sources are among the most important ingredients for the development of a human society with sustainable environmental footprint. Among these, photovoltaics (PV) plays a key role and is therefore a field of intense research. The key parameters of a solar cell technology includes not only the energy conversion efficiency but also the operating lifetime and the overall cost of the energy produced. The latter must also be compared with other energy sources. The optimization of all these different aspects involves research across the whole photovoltaics value chain, starting from material science up to system optimization. Development of new solar cell device concepts is as important as search for new materials with more suitable optoelectronic properties or improved approaches for PV module design and integration in power distribution systems. This requires a comprehensive view on PV technology across all scales, from the atomic to the macroscopic and industrial scale. An important aspect of PV research and of development of new devices and systems, is theoretical modeling as an indispensable tool for both basic understanding and device optimization. This involves modeling also on all scales, from the microscopic properties of materials and nanostructures up to the behavior of PV modules. During the last decade, multiscale approaches have seen increasing interest for application in numerical simulation of electronic devices. In particular, modeling and understanding of advanced photovoltaic devices are expected to benefit from multiscale modeling, which allows describing consistently both macroscopic device behavior and local microscopic processes governing light absorption, loss mechanisms, carrier transport, and extraction. In fact, many advanced PV concepts rely on effects or contain structural features that are insufficiently described by standard numerical simulation approaches or semianalytic models, both regarding electronic and optical properties. The different length scales of the electronic and optical degrees of freedoms specifically lead to an intrinsic need for multiscale simulation, which is accentuated in many advanced photovoltaics concepts including nanostructured regions. Moreover, the active layers in solar cells generally require to have a certain thickness and a large overall device area, in order to absorb a sufficient amount of light. This special issue is an attempt to collect articles on modeling of PV devices and systems on all scales. It includes two experimental articles, one shedding some light on photoreflectance measurements when probing above the pump beam energy and the other discussing morphology in hybrid lead halide perovskite solar cells. One article describes numerical modeling of Cu2O on Si tandem cells based on a semiempirical approach. A further contribution shows a physics-based model of a quantum dot solar cell, including a comparison with experimental data. The remaining two papers deal with system relevant aspects, namely, power point tracking and electrical inverters for connecting PV modules or power plants with appliances.

Energy Production in Smart Cities by Utilization of Kinetic Energy of Vehicles Over Speed Breaker

Smart city deals with the problems of rapid urbanization and population growth by optimal utilization of all available resources. There are other driving factors such as clean energy programmes, a low carbon economy and distributed energy resources that are included in a smart city concept. Therefore, in this article, the authors proposed a clean energy generating model by utilizing the kinetic energy of vehicles over a speed breaker. The article focused on the design, modelling, and simulation of an electromechanical system for generating electrical power from the kinetic energy of vehicles passing over speed breakers. To facilitate simulation, a model of the electromechanical system is developed in MATLAB/Simulink. Further, MULTISIM 14 software is utilized for power electronic device modelling and simulation. Simulation results for power generation are obtained considering four units of rotational induction generators and two units of translational induction generators.

Full-band quantum simulation of electron devices with the pseudopotential method: Theory, implementation, and applications

This paper presents the theory, implementation, and application of a quantum transport modeling approach based on the nonequilibrium Green's function formalism and a full-band empirical pseudopotential Hamiltonian. We here propose to employ a hybrid real-space/plane-wave basis that results in a significant reduction of the computational complexity compared to a full plane-wave basis. To this purpose, we provide a theoretical formulation in the hybrid basis of the quantum confinement, the self-energies of the leads, and the coupling between the device and the leads. After discussing the theory and the implementation of the new simulation methodology, we report results for complete, self-consistent simulations of different electron devices, including a silicon Esaki diode, a thin-body silicon field effect transistor (FET), and a germanium tunnel FET. The simulated transistors have technologically relevant geometrical features with a semiconductor film thickness of about 4 nm and a channel length ranging from 10 to 17 nm. We believe that the newly proposed formalism may find applications also in transport models based on ab initio Hamiltonians, as those employed in density functional theory methods.

Quantum dissipation with conditional wave functions: Application to the realistic simulation of nanoscale electron devices

Without access to the full quantum state, modeling dissipation in an open system requires approximations. The physical soundness of such approximations relies on using realistic microscopic models of dissipation that satisfy completely positive dynamical maps. Here we present an approach based on the use of the Bohmian conditional wave function that, by construction, ensures a completely positive dynamical map for either Markovian or non-Markovian scenarios, while allowing the implementation of realistic dissipation sources. Our approach is applied to compute the current-voltage characteristic of a resonant tunneling device with a parabolic-band structure, including electron-lattice interactions. A stochastic Schr\"odinger equation is solved for the conditional wave function of each simulated electron. We also extend our approach to (graphene-like) materials with a linear band-structure using Bohmian conditional spinors for a stochastic Dirac equation.

Electronic locomotive power supply device simulation and harmonic analysis

The DC600V electricity supply device plays an important role in locomotive. In this device, the main circuit is one kind of single-phase full-bridge half-controlled rectifier circuit. In this paper, first of all, we analyze the theory of main circuit. Secondly, accurate model is built through MATLAB/Simulink. We obtain the waveform of key parameters and harmonic analysis. The results of simulation waveforms show that the model is correct. It is proved that the built model flexible, convenient and intuitive. Meanwhile, it can be used for further fault detection and analysis.

Modeling and simulation of single electron transistor with master equation approach

In this paper, we discuss modeling and simulation of single dot Single Electron Transistor (SET) using master equation approximation. For SET modeling and simulation, master equation method treats the electron tunneling and its transition probabilistically. The probability of electron tunneling is used to determine the current density in accordance with selected input parameters. The calculation results show fairly accurate electrical characteristics of SET as compared with experimental data. Staircase pattern from I-V are clearly obtained as the main role of coulomb blockade effect in SET system. We also extend our calculation by introduce some additional parameters such as; the effect of working temperature, gate voltage dependent, and the influence of resistance to the device characteristic. We found that increasing operational temperature will promote higher current density, both in forward and reverse bias region. In the case of using single dot with 30 nm × 80 nm × 125 nm dimension, coulomb blockade effect could be reduced by applying gate voltage higher than 3V and setting drain resistance higher than source's. Our studies show an alternative approach in modeling and simulation of electronic devices and could be potential for development of novel nanoelectronic devices.

Delaunay–Voronoi surface integration: a full‐wave electromagnetics discretization for electronic device simulation

SummaryA promising time domain electromagnetics numerical method for treating the highly nonlinear problem of charge transport in electronic devices called Delaunay–Voronoi surface integration is presented. This method couples the rotational electric and magnetic fields governed by Ampere's and Faraday's laws with the electrostatic potential dictated by Poisson's equation in a simultaneous solution. Discretization of the governing equations using dual meshes and the relevant boundary conditions are presented. The engineering application details specific to electronic device simulation are treated, and an example calculation is shown to compare with an analytical solution for propagation in a waveguide. Benchmark results are presented for the rotational equations, Poisson's equation, and the complete set of electromagnetic equations. Copyright © 2016 John Wiley & Sons, Ltd.

Advances in Computational Modeling of Electronic Devices Based on Graphene

Nowadays electronic devices such as $p-n$ diodes, field-effect transistors, logic gates, mixers, ring oscillators, and memories have been designed based on single, bi and/or multi-layer graphene. However, a lot of effort must be developed to integrate mathematical models into new simulators for electronic devices based on nanomaterials such as those based on carbon nanotubes, fullerenes, and graphene. Main contributions with respect to modeling and simulation of electronic devices based on graphene and developed in the ultimate years are analyzed here. In addition, future perspectives related with mathematical modeling of electronic devices based on graphene are discussed.