Nonlinear free vibration of piezoelectric semiconductor doubly-curved shells based on nonlinear drift-diffusion model

In this paper, the nonlinear free vibration behaviors of the piezoelectric semiconductor(PS) doubly-curved shell resting on the Pasternak foundation are studied within the framework of the nonlinear drift-diffusion(NLDD) model and the first-order shear deformation theory. The nonlinear constitutive relations are presented, and the strain energy, kinetic energy, and virtual work of the PS doubly-curved shell are derived.Based on Hamilton's principle as well as the condition of charge continuity, the nonlinear governing equations are achieved, and then these equations are solved by means of an efficient iteration method. Several numerical examples are given to show the effect of the nonlinear drift current, elastic foundation parameters as well as geometric parameters on the nonlinear vibration frequency, and the damping characteristic of the PS doublycurved shell. The main innovations of the manuscript are that the difference between the linearized drift-diffusion(LDD) model and the NLDD model is revealed, and an effective method is proposed to select a proper initial electron concentration for the LDD model.

Asymptotic Behavior of Global Smooth Solution of 1-D Quasineutral Drift Diffusion Model for Semiconductors

在这份报纸，我们学习半导体的 1-d quasineutral 飘移散开模型的起始的边界价值问题的全球性光滑的答案的 asymptotic 行为。我们证明这个问题的光滑的答案(到平衡的结束) 收敛到唯一的静止答案。

ASYMPTOTIC BEHAVIOR OF THE DRIFT-DIFFUSION SEMICONDUCTOR EQUATIONS

This paper is devoted to the long time behavior for the Drift-diffusion semiconductor equations. It is proved that the dynamical system has a compact, connected and maximal attractor when the mobilities are constants and generation-recombination term is the Auger model; as well as the semigroup S(t) denned by the solutions map is differential. Moreover the upper bound of Hausdorff dimension for the attractor is given.

A POSITIVITY-PRESERVING FINITE ELEMENT METHOD FOR QUANTUM DRIFT-DIFFUSION MODEL

In this paper,we propose a positivity-preserving finite element method for solving the three-dimensional quantum drift-diffusion model.The model consists of five nonlinear elliptic equations,and two of them describe quantum corrections for quasi-Fermi levels.We propose an interpolated-exponential finite element(IEFE)method for solving the two quantum-correction equations.The IEFE method always yields positive carrier densities and preserves the positivity of second-order differential operators in the Newton linearization of quantum-correction equations.Moreover,we solve the two continuity equations with the edge-averaged finite element(EAFE)method to reduce numerical oscillations of quasi-Fermi levels.The Poisson equation of electrical potential is solved with standard Lagrangian finite elements.We prove the existence of solution to the nonlinear discrete problem by using a fixed-point iteration and solving the minimum problem of a new discrete functional.A Newton method is proposed to solve the nonlinear discrete problem.Numerical experiments for a three-dimensional nano-scale FinFET device show that the Newton method is robust for source-to-gate bias voltages up to 9V and source-to-drain bias voltages up to 10V.

Combined Electromagnetic and Drift Diffusion Models for Microwave Semiconductor Device

In this work, we present a numerical model to solve the drift diffusion equations coupled with electromagnetic model, where all simulations codes are implemented using MATLAB code software. As first, we present a one-dimensional (1-D) PIN diode structure simulation achieved by solving the drift diffusion model (DDM). Backward Euler algorithm is used for the discretization of the proposed model. The aim is to accomplish time-domain integration. Also, finite different method (FDM) is considered to achieve space-Domain mesh. We introduced an iterative scheme to solve the obtained matrix systems, which combines the Gummel’s iteration with an efficient direct numerical UMFPACK method. The obtained solutions of the proposed algorithm provide the time and space distribution of the unknown functions like electrostatic potential and carrier’s concentration for the PIN diode. As second case, the finite-difference time-domain (FDTD) technique is adopted to analyze the entire 3-D structure of the stripline circuit including the lumped element PIN diode. The microwave circuit is located in an unbounded medium, requiring absorbing boundaries to avoid nonphysical reflections. Active device results were presented and show a good agreement with other reference. Electromagnetic results are qualitatively in agreement with other results obtained using SILVACO-TCAD.

Existence of Global Attractor for the One-Dimensional Bipolar Quantum Drift-Diffusion Model

In this paper, we investigate a one-dimensional bipolar quantum drift-diffusion model from semiconductor devices. We mainly show the long-time behavior of solutions to the one-dimensional bipolar quantum drift-diffusion model in a bounded domain. That is, we prove the existence of the global attractor for the solution.

Asymptotic Behavior of Solutions of the Bipolar Quantum Drift-Diffusion Model in the Quarter Plane

In this study, we consider the one-dimensional bipolar quantum drift-diffusion model, which consists of the coupled nonlinear fourth-order parabolic equation and the electric field equation. We first show the global existence of the strong solution of the initial boundary value problem in the quarter plane. Moreover, we show the self-similarity property of the strong solution of the bipolar quantum drift-diffusion model in the large time. Namely, we show the unique global strong solution with strictly positive density to the initial boundary value problem of the quantum drift-diffusion model, which in large time, tends to have a self-similar wave at an algebraic time-decay rate. We prove them in an energy method.

Asymptotic Behavior of Solutions for the One-Dimensional Drift-Diffusion Model in the Quarter Plane

In this paper, we study the classical drift-diffusion model arising from the semiconductor device simulation, which is the simplest macroscopic model describing the dynamics of the electron and the hole. We prove the global existence of strong solutions for the initial boundary value problem in the quarter plane. In particular, we show that in large time, these solutions tend to the nonlinear diffusion wave which is different from the steady state, at an algebraic time-decay rate. As far as we know, this is the first result about the nonlinear diffusion wave phenomena of the solutions for the one-dimensional drift-diffusion model in the quarter plane.

量子流体动力学等温模型的拟中性极限

研究三维量子流体动力学等温模型,它是用来模拟超小半导体器件发生量子效应的宏观量子模型之一,反映了电子浓度、电子速度以及静电场位势之间的非线性关系.该模型中含有非线性三阶导数项,这在数学上给研究该模型带来了困难.在周期边界条件下。

半导体宏观数学模型的拟中性极限

首先给出了半导体材料科学中的各种数学模型 ,然后综述半导体材料科学的宏观模型拟中性极限问题的有力数学分析结果 .使用熵 (Entropy)

半导体中拟中性漂移扩散模型的适定性(英文)

研究了半导体中拟中性漂移扩散模型的适定性,证明了其局部解和整体解的存在唯一性,并给出了几个稳态奇性解的例子.

Study of the Discharge Mode in Micro-Hollow Cathode

In this study, micro-hollow cathode discharge （MHCD） is investigated by a fluid model with drift-diffusion approximation. The MHC device is a cathode/dielectric/anode sandwich structure with one hole of a diameter D=200 um. The gas is a Ne/Xe mixture at a pressure p=50-500 Torr. The evolutions of the discharge show that there are two different discharge modes. At larger pD the discharge plasma and high density excited species expand along the cathode surface and, a ringed discharge mode is formed. At smaller pD, the discharge plasma and the excited species expand along the axis of the cathode aperture to form a columnar discharge.

EXISTENCE OF WEAK SOLUTIONS TO A DEGENERATE STEAD-STATE SEMICONDUCTOR EQUATIONS

In this paper, we consider a degenerate steady-state drift-diffusion model for semiconductors. The pressure function used in this paper is （）（s） = s~α（α 〉 1）. We present existence results for general nonlinear diffhsivities for the degenerate Dirichlet-Neumann mixed boundary value problem.

The Asymptotic Behavior and the Quasineutral Limit for the Bipolar Euler-Poisson System with Boundary Efects and a Vacuum

In this paper, a one-dimensional bipolar Euler-Poisson system(a hydrodynamic model) from semiconductors or plasmas with boundary efects is considered. This system takes the form of Euler-Poisson with an electric field and frictional damping added to the momentum equations. The large-time behavior of uniformly bounded weak solutions to the initial-boundary value problem for the one-dimensional bipolar Euler-Poisson system is firstly presented. Next, two particle densities and the corresponding current momenta are verified to satisfy the porous medium equation and the classical Darcy's law time asymptotically. Finally, as a by-product, the quasineutral limit of the weak solutions to the initial-boundary value problem is investigated in the sense that the bounded L∞entropy solution to the one-dimensional bipolar Euler-Poisson system converges to that of the corresponding one-dimensional compressible Euler equations with damping exponentially fast as t → +∞. As far as we know, this is the first result about the asymptotic behavior and the quasineutral limit for the one-dimensional bipolar Euler-Poisson system with boundary efects and a vacuum.

Cs_(2)TiI_(6):A potential lead-free all-inorganic perovskite material for ultrahigh-performance photovoltaic cells and alpha-particle detection

The lead contamination and long-term stability are the two important problems limiting the commercialization of organic–inorganic lead halide perovskites.In this study,through an innovative multi-scale simulation strategy based on the first-principle calculations coupling with drift-diffusion model and Monte Carlo method,a new discovery is shed on the vacancy-ordered double perovskite Cs_(2)TiI_(6),a potential nontoxic and stable perovskite material for high-performance solar cell andα-particle detection.The excellent photon absorption character and ultrahigh carrier mobility(μn=2.26×10^(4)cm^(2)/Vs,μp=7.38×10^(3)cm^(2)/Vs)of Cs_(2)TiI_(6)induce ultrahigh power conversion efficiency(PCE)for both single-junction solar cell(22.70%)and monolithic all-perovskite tandem solar cell(26.87%).Moreover,the outstanding device performance can be remained even in high energy charge particle detection(α-particle)with excellent charge collection efficiency(CCE=99.2%)and mobility-lifetime product(μτh=1×10^(–3)cm^(2)/V).Furthermore,to our surprise,the solar cell andα-particle detector based on Cs_(2)TiI_(6)material are able to withstand ultrahigh fluence proton beam up to 1013 and 1015 p/cm2 respectively,which strongly suggests that semiconductor devices based on Cs_(2)TiI_(6)material are able to apply in the astrospace.The multi-scale simulation connecting from material to device reveals that Cs_(2)TiI_(6)perovskite has the great potential for photovoltaic cells,α-particle detection and even their space application.

Optimizing Photovoltaic Performance by Kinetic Quenching of Layered Heterojunctions

The mixing morphology control plays a crucial role in photovoltaic power generation,yet this specific effect on device performances remains elusive.Here,we employed computational approaches to delineate the photovoltaic properties of layered heterojunction polymer solar cells with tunable mixing morphologies.One-step quench and two-step quench strategies were proposed to adjust the mixing morphology by thermodynamic and kinetic effects.The computation for the one-step quench revealed that modulating interfacial widths and interfacial roughness could significantly promote the photovoltaic performance of layered heterojunction polymer solar cells.The two-step quench can provide a buffer at a lower temperature before the kinetic quenching,leading to the formation of small-length-scale islands connected to the interface and a further increase in photovoltaic performance.Our discoveries are supported by recent experimental evidence and are anticipated to guide the design of photovoltaic materials with optimal performance.