Modelling and simulation of advanced semiconductor devices

This paper presents a modelling and simulation study of advanced semiconductor devices. Different Technology Computer Aided Design approaches and models, used in nowadays research are described here. Our discussions are based on numerous theoretical approaches starting from first principle methods and continuing with discussions based on more well stablished methods such as Drift-Diffusion, Monte Carlo and Non-Equilibrium Green’s Function formalism

Non-Equilibrium Green’s Function Method in Matrix Representation and Model Transport Problems of Nanoelectronics

Non-equilibrium Green’s functions method in matrix representation is presented and applied to model transport problems for 1D and 2D conductors using a nearest neighbor orthogonal tight-binding model in the frame of the «bottom-up» approach of modern nanoelectronics. Simple methods to account for electric contacts in Schrödinger equation to solve quantum electron transport problems are given. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/3535

Design Considerations of Structural Parameters in Resonant Tunneling Diode by None-Equilibrium Green Function Method

This paper presents the effects of structural parameters like Quantum well width, barrier width, spacer width, contact width and contact doping, on performance of Resonant Tunneling Diode using full quantum simulation. The simulation is based on a self-consistent solution of the Poisson equation and Schrodinger equation with open boundary conditions, within the non-equilibrium Green’s function formalism. The effects of varying the structural parameters is investigated in terms of the output current, peak current, valley current, peak to valley current ratio and the voltage associated with the peak current. Simulation results illustrate that the device performance can be improved by proper selection of the structural parameters

Design Considerations of Structural Parameters in Resonant Tunneling Diode by None-Equilibrium Green Function Method

This paper presents the effects of structural parameters like Quantum well width, barrier width, spacer width, contact width and contact doping, on performance of Resonant Tunneling Diode using full quantum simulation. The simulation is based on a self-consistent solution of the Poisson equation and Schrodinger equation with open boundary conditions, within the non-equilibrium Green’s function formalism. The effects of varying the structural parameters is investigated in terms of the output current, peak current, valley current, peak to valley current ratio and the voltage associated with the peak current. Simulation results illustrate that the device performance can be improved by proper selection of the structural parameters

First-Principles Calculations of Electronic and Transport Properties of Nanowires

The goal of this research is to find out the electronic structure and transport property of nanowires that we are interested in. As Moore’s law is faltering, scientists are trying to use different methods to continue to increase computer’s computing power like using carbon nanotubes or quantum transistors. In the spirit of this, semiconducting nanowires constituted of atomic units and choices of ligands are proposed to mimic the functions of transistors to achieve the goal of increasing computing power. Electronic structure and electron transport calculations have been conducted based on the density function theory and the non-equilibrium Green’s function (NEGF) method to show the effect of ligands on the nanowire

Non-equilibrium Green\u27s function (NEGF) simulation of metallic carbon nanotubes including vacancy defects

The electronic behavior of metallic carbon nanotubes under the influence of externally applied electric fields is investigated using the Non-Equilibrium Green’s function method self consistently coupled with three-dimensional (3D) electrostatics. A nearest neighbor tight binding model based on a single pz orbital for constructing the device Hamiltonian is used. The 3D Poisson equation is solved using the Finite Element Method. Carbon nanotubes exhibit a very weak metallic behavior, and external electric fields can alter the electrostatic potential of the tubes significantly. A single vacancy defect in the channel of a metallic carbon nanotube can decrease its conductance by a factor of two. More than one vacancy can further decrease the conductance

Spin-filtering effect in the transport through a single-molecule magnet Mn12_{12} bridged between metallic electrodes

Electronic transport through a single-molecule magnet Mn$_{12}$ in a two-terminal set up is calculated using the non-equilibrium Green's function method in conjunction with density-functional theory. A single-molecule magnet Mn$_{12}$ is bridged between Au(111) electrodes via thiol group and alkane chains such that its magnetic easy axis is normal to the transport direction. A computed spin-polarized transmission coefficient in zero-bias reveals that resonant tunneling near the Fermi level occurs through some molecular orbitals of majority spin only. Thus, for low bias voltages, a spin-filtering effect such as only one spin component contributing to the conductance, is expected. This effect would persist even with inclusion of additional electron correlations.Comment: Accepted for publication at J. Appl. Phy