Introducing energy broadening in semiclassical Monte Carlo simulations

Combining an insight on the quantum transport given by the Wigner function formalism and the classical perturbation theory, an algorithm has been developed that allows the introduction of collisional broadening in semiclassical electron transport Monte Carlo (MC) simulations. In the proposed algorithm, electron energy and momentum are treated as independent variables; the laws of energy and momentum conservation are fulfilled at each scattering event, but the relationship between energy and momentum is not given by the traditional expression, since Bloch states are not eigenstates of the total Hamiltonian. The results obtained for a simple model semiconductor demonstrate that the non-physical instabilities observed in previous attempts to introduce collisional broadening in semiclassical MC simulations have been removed. The algorithm is suitable for application in MC simulations of realistic device models.     

Uncertainty analysis of a commercial microwave noise temperature measurement system using Monte Carlo simulations

A Monte Carlo simulation, a non‐linear fitting routine, and an uncertainty extraction routine are used to analyze the uncertainty of a commercial microwave noise temperature measurement system. Measured data for an S/C band synthetic FET‐based cold load, two microwave solid‐state noise diode hot loads, and an ambient load is obtained, and the measurement system uncertainties are subsequently assessed using different DUTs. An estimation of the measurement system uncertainties is determined for a range of DUT temperatures, and the results are consistent with the noise temperature uncertainties calculated from the measured data at the same frequency. Copyright © 2010 John Wiley & Sons, Ltd.     

Using Monte Carlo simulations to introduce tolerance design toundergraduates

The effect of parameter variations on engineering systems is often neglected in undergraduate electrical engineering education. This paper proposes using Monte Carlo simulation to introduce students to tolerance design in the required electronics course where students perform designs using real electronic components. Monte Carlo simulation requires very little statistical background for the student and many software packages have built-in random number generators or even Monte Carlo simulation options, As a result, tolerance design is easily introduced to students in a short time frame. This paper discusses methods of introducing Monte Carlo simulations to the students in less than one hour of lecture. Example laboratory exercises and homework problems are described     

Whole field computation using Monte Carlo method

Monte Carlo methods are generally known for solving field problems one point at a time, unlike other numerical methods such as the finite difference and finite element methods which provide the solution at all the grid nodes simultaneously. This paper provides a Monte Carlo technique for obtaining the solution everywhere at once. The technique uses absorbing Markov chains to obtain the transition probabilities for all of the grid nodes at once. The procedure is illustrated with some examples for homogeneous and inhomogeneous, rectangular and axisymmetric solution regions, and is found to be accurate. © 1997 John Wiley & Sons, Ltd.     

Tetrahedral elements in self-consistent parallel 3D Monte Carlo simulations of MOSFETs

Novel thin-body architectures with complex geometry are becoming of large interest because they are expected to deliver the ITRS prescribed on-current when semiconductor transistors are scaled into nanometer dimensions. We report on the development of a 3D parallel Monte Carlo simulator coupled to a finite element solver for the Poisson equation in order to correctly describe the complex domains of advanced FinFET transistors. We study issues such as charge assignment, field calculation, treatment of contacts and parallelisation approach which have to be taken into account when using tetrahedral elements. The applicability of the simulator is demonstrated by modelling a 10 nm gate length double gate MOSFET with a body thickness of 6.1 nm.     

Monte Carlo simulations of nanometric devices beyond the “mean-field” approximation

For nanoscale electron devices, the role of a single-electron (or a single-impurity) can have a large impact on their electrical characteristics. A new method for introducing the long-range and short-range Coulomb interaction in semiconductor semi-classical Monte Carlo simulations is presented. The method is based on directly dealing with a many-particle system by solving a different Poisson equation for each electron. The present work shows the numerical viability of this alternative approach for nanoscale devices with few (<100) electrons. The method is compared with the traditional “mean-field” Monte Carlo simulations. It is shown, numerically, that the “mean-field” approximation produces important errors for aggressively-scaled devices.     

Investigating distributed generation systems performance using Monte Carlo simulation

A novel algorithm to evaluate the performance of electric distribution systems, including distributed generation (DG) is proposed. This algorithm addresses the deterministic and the stochastic natures of these electrical systems. Monte Carlo simulation is employed to solve the system operation randomness problem, taking into consideration the system operation constraints. The uncertainties in the locations, exported penetration level, and the states (on or off) of the DG units constitute the random parameters of the studied systems. The introduced algorithm incorporates these parameters with the traditional Newton-Raphson solution of the power flow equations. Monte Carlo simulation is implemented to perform the analysis of all the possible operation scenarios of the system under study and thus ensure the validity of the results. The proposed algorithm is employed to obtain the hourly power flow solution for a typical DG connected system. The system loading follows several typical load curves based on load bus types. Furthermore, new hourly steady-state operating system parameters are evaluated to describe the system behavior under the DG random operation. The results obtained are presented and discussed.     

Adequacy assessment of distributed generation systems using Monte Carlo Simulation

This paper presents a Monte Carlo-based method for the adequacy assessment of distributed generation systems. The state duration sampling approach is employed in this paper to model the operating histories of the installed distributed generators. A general procedure to assess the ability of the system power capacity to meet the total demand is presented and implemented in a typical case study where several distributed generation units are running in parallel within a sample distribution system and the system margins and the average amount of unsupplied loads are estimated using Monte Carlo simulation. The results obtained are presented and a new perspective to the power management of distribution systems is discussed.     

Quantum Monte Carlo simulation of dissipative transport using Bohmian trajectories

In this paper, a Monte Carlo method is proposed, which utilizes Bohmian trajectories to simulate dissipative transport in one-dimensional quantum devices. The proposed method, similar to the classical Monte Carlo method, is capable of simulating both elastic and inelastic scattering effects, with the distinction that quantum effects such as tunneling are also included. At first, the Bohmian trajectories for the wave packets injected from the right and the left contacts are obtained by solving the time-dependent Schrodinger equation, and then scattering effects are included via stochastic changes applied on the electron trajectories. We have shown that the results of the proposed model agree well with those of NEGF formalism.     

Scattering and space-charge effects in Wigner Monte Carlo simulations of single and double barrier devices

Transport in single and double barrier devices is studied using a Monte Carlo solver for the Wigner transport equation. This approach allows the effects of tunneling and scattering to be included. Several numerical methods have been improved to render the Wigner Monte Carlo technique more robust, including a newly developed particle annihilation algorithm. A self-consistent iteration scheme with the Poisson equation was introduced. The role of scattering and space charge effects on the electrical characteristics of n-i-n nanostructures, ultra-scaled double gate MOSFETs, and GaAs resonant tunneling diodes is demonstrated. An erratum to this article can be found at     

Bulk electric system well-being analysis using sequential Monte Carlo simulation

There is growing interest in combining deterministic considerations with probabilistic assessment in order to evaluate the "system well-being" of a composite generation and transmission system and to evaluate the likelihood not only of entering a complete failure state but also the likelihood of being very close to trouble. This paper presents bulk electric system well-being analysis using sequential Monte Carlo simulation. This approach provides accurate frequency and duration assessments and the index probability distributions associated with the mean values. The basic N-1 security criterion is used as the deterministic requirement for incorporating a deterministic consideration in a probabilistic assessment to monitor system well-being. The results shown in this paper indicate that the system well-being concept can provide comprehensive knowledge on what the degree of system vulnerability might be under a particular system condition. The basic concepts and their application in composite power system well-being analysis are illustrated by application to a small practical test system.     

Scaling effects in AlGaN/GaN HEMTs: Comparison between Monte Carlo simulations and experimental data

AlGaN/GaN based HEMTs are showing an unexpected behaviour of the transport characteristic compared to the GaAs and InGaAs HEMT technology. A downscaling of the source-gate and gate-drain lengths of GaN HEMTs produced a maximum output current increase, which is not compatible with a framework where the electrons velocity is saturated. Monte Carlo simulations are able to reproduce this experimental behaviour showing how this phenomena is related to intrinsic velocity-field relation in GaN. We attribute the lack of overshooting phenomena to the high scattering rate of III–V nitrides and to the strong localisation of the high electric field region. We also have found that such suppression could be avoided with a proper scaling of the devices.     

Frequency-duration analysis of composite distribution system using a non-sequential Monte Carlo simulation

This paper presents a methodology for composite distribution system well being analysis based on non-sequential Monte Carlo simulation technique accounting uncertainties in capacity of distribution substation and distributed generation (DG). The method is based on a system state transition sampling approach which is used to calculate frequency and duration indices along with probabilities in healthy state, marginal state and risky state for a composite distribution system. Capacity of distribution substation and distributed generations are considered as normally distributed i.e. continuous capacity. The effectiveness of the method for evaluation of annual well being indices is demonstrated for a sample test system with DG capacity variation considering a seven step load model based on annual load duration curve. A comparative study is carried out which illustrates the effect of distributed generation capacity on well being indices of a distribution system.     

Model plasma dispersion functions for SO phonon scattering in Monte Carlo simulations of high-κ dielectric MOSFETS

We have developed an accurate Padé approximant for the plasma dispersion function that is valid for degenerate semiconductors that occur in ultra-small MOSFETs. The new approximant is based on a two pole model that enables a simple evaluation of the Lindhard dielectric function for the full dynamic response of electrons of any degeneracy. The importance of this result is that it enables a fast numerical algorithm for determining the energies and scattering strengths of coupled plasmon-phonon modes in silicon MOSFET devices with high-κ gate stacks. Moreover, the formalism allows the systematic inclusion of Landau damping and other processes such as collisional damping that damp out some of the modes at particular ranges of wave vector. The new model is a non-trivially scaled model of a previous approximant derived for Boltzmann statistics. The new model reduces to the classical result in the appropriate limit. Results are presented that compare the exact numerically computed complex plasma dispersion function with the new Padé approximant model. Comparison is also made between exact numerical calculations and the Padé approximant model for static screening. A brief outline is made of the potential application to high-κ gate stack devices where the formalism should provide a significantly large reduction in complexity that will enable efficient Monte Carlo simulation of SO phonon and plasmon scattering.     

Monte Carlo simulation of nanoelectronic devices

The Monte Carlo simulation method is used to analyze the behavior of electron and hole mobility in different nanoelectronic devices including double gate transistors and FinFETs. The impact of technological parameters on carrier mobility is broadly discussed, and its behavior physically explained. Our main goal is to show how mobility in multiple gate devices compares to that in single gate devices and to study different approaches to improve the performance of these devices. Simulations of ultrashort channel devices taking into account quantum effects are also shown.     

Monte Carlo Analysis of System Tolerance

The effect on system performance of variation of the values of component parts is a topic which should be included in the undergraduate engineering curriculum. Two subroutines are presented in this paper which simplify the problem so that meaningful problems can be solved by the sophomore or junior engineering student. Values for system components are selected according to a probability density function and the resulting system performance is calculated. The resulting values of system performance are presented in the form of a histogram. The advantage here is that the student can very easily get a picture of the variation of a system perfonnance factor due to component variations.     

Power system reliability evaluation using learning vector quantization and Monte Carlo simulation

Artificial Neural Networks (ANN) based on the Learning Vector Quantization (LVQ) algorithm have received considerable attention as pattern classifiers. This paper proposes a new method for power system reliability evaluation combining Monte Carlo simulation and LVQ which greatly reduces the computing burden of the loss of load probability calculation compared to Monte Carlo simulation only. A case study of the IEEE RTS system is presented demonstrating the efficiency of this approach.     

Production costing strategy for optimal SO2 compliance using Monte Carlo simulation

One of the main goals of electric utilities is to meet the required load demand in the most cost effective manner. With the continuing emphasis on environmental factors and the addition of the Clean Air Act Amendments of November 1990, cost effective solutions must now be subject to environmental considerations. This paper describes a simple framework which uses the Monte Carlo method to develop an economic and emissions based objective function for use in a production cost model. A computer program has been developed to implement this method on a DEC 3100 workstation. System studies are performed to illustrate the technique.     

基于自适应蒙特卡洛法的磁场辐射发射测量不确定度评定

针对测量不确定度评定中测量不确定度表示指南法（GUM）不适用于输入输出变量关系非线性或输出变量非正态分布的情况,提出采用自适应蒙特卡洛法（AMCM）评定25 Hz～100 kHz磁场辐射发射（RE101）测试的测量不确定度。首先阐述蒙特卡洛法（MCM）和AMCM评定测量不确定度的计算步骤,其次分别用AMCM和GUM法评定RE101测量不确定度,在相同的包含概率下比较两种方法的覆盖区间差值与数值允差,表明AMCM的评定结果可靠性更高,适用于RE101测量不确定度评定。AMCM可以推广到其他电磁兼容测试项目的不确定度评定中,将有效提高不确定度评定的可靠性。