This short presentation will describe the idea behind MD simulations and demonstrate its use in real applications.

This talk covers the big technological changes in the 20th and 21st century that were correctly predicted by Gordon Moore in 1965. Moore\‘s Law states that the number of transistors on a silicon chip doubles every technology generation. In 1960s terms that meant every 12 months and currently this means every 18-24 months. This talk explores the challenges of doubling transistors on chips and some new technologies examined by researchers.

In non-specialist language, this talk introduces CMOS technology used for modern electronics. Beginning with an explanation of \“CMOS,\” the speaker relates basic system considerations of transistor design and identifies future challenges for CMOS electronics. Anyone with an elementary understanding of transistors will benefit from this presentation.

This set of powerpoint slides series provides insight on what are the tools available for modeling devices that behave either classically or quantum-mechanically. An in-depth description is provided to the approaches with emphasis on the advantages and disadvantages of each approach. Conclusions are drawn about the applicability of each approach. There are additional teaching materials that can be found on the nanohub that give more in-depth knowledge about each topic being addressed in this …

In physics, the WKB (Wentzel–Kramers–Brillouin) approximation, also known as WKBJ (Wentzel–Kramers–Brillouin–Jeffreys) approximation, is the most familiar example of a semiclassical calculation in quantum mechanics in which the wavefunction is recast as an exponential function, semiclassically expanded, and then either the amplitude or the phase is taken to be slowly changing. This method is named after physicists Wentzel, Kramers, and Brillouin, who all developed it in 1926. In …

The composites with opposite signs of the dielectric permittivity in two orthogonal directions, known as the hyperbolic metamaterials, represent a new "universality class" of optical media, with the light behavior which is qualitatively different from that in either metals or dielectrics. Propagating waves in such "electromagnetic hyperspace" do not suffer from the diffraction limit on the optical resolution, leading to the hyperlens - the device capable of producing magnified far-field images of subwavelength objects, while the broadband super-singularity of the photonic density of states in hyperbolic media results in a dramatic change in a variety of phenomena, from spontaneous emission to light propagation and scattering.

Mr. Keating will discuss the correct approach and methods to use when writing technical papers in English. He will emphasize style and usage, covering several difficult issues that ESL (English as a Second Language) writers often encounter. Among them will be inconsistencies, simplicity, clarity, ambiguity, idioms, overstatement, and rhythm. Examples of weak English taken from actual proposals, books, journals, and presentations will be presented along with methods that will solve these …

Quasi 1-D metal oxide single crystal chemiresistors are close to occupy their specific niche in the real world of solid state sensorics. Potentially, the major advantage of this kind of sensors with respect to available granular thin film sensors will be their size and stable, reproducible and quantifiable performance in a wide range of operating conditions. The performance of such a gas sensor and especially its sensitivity is determined by its materials-specific surface chemistry as well as the size and shape of its active element(s). We report on the array of methods that allow one to fabricate, functionalize and characterize chemiresistors and chemi-FETs made of metal oxide nanowires. In particular, we grow nanowires with pre-programmed morphologies, which are most suitable for sensorics applications. To evaluate the heat management in the chemiresistor device we have performed a comparative study of the nanostructures with different thermal coupling with the support. To address the surface chemistry of the nanowires with greater details, we have tested a range of spectroscopy and imaging techniques to address local transport particularities taking place in the individual operating metal oxide nanostructure sensor. In particular, we were using Scanning Surface Potential Microscopy (SSPM) to investigate dc potential distributions in an operating device. We also have successfully implemented synchrotron radiation based photoelectron emission spectro- microscopy (PEEM) to explore submicron compositional and electronic (work function) inhomogeneouties in individual metal oxide nanowire wired as a chemiresistor. Finally, recent real world prototype devices such as gas sensors and e-noses based on metal oxide nanowires will be discussed.

Modeling the electrical effects of radiation damage in semiconductor devices requires a detailed description of the properties of point defects generated during and subsequent to irradiation. Such modeling requires physical parameters, such as defect electronic levels, to describe carrier recombination. Density functional theory (DFT) is the method of choice for first-principles simulations of defects. However, DFT typically hugely underestimates the fundamental band gap in semiconductors, and the band gap is the energy scale of interest for defect levels. Moreover, boundary conditions in the supercell approximation used in DFT calculations of defects also can inject large errors and uncertainties. I describe a new, more rigorous methodology for supercell calculations, implemented in the SeqQuest DFT code, that incorporates a proper treatment of electrostatic boundary conditions, locates a fixed chemical potential for the net defect electron charge, includes the bulk dielectric response, and creates a robust computational model of isolated defects. Using this methodology, the computed DFT defect level spectrum for a wide variety of Si defects spans the experimental Si gap, i.e., exhibits no band gap problem, and the DFT results agree remarkably well with experiment for those values that are experimentally known. The new scheme adds rigor to computing defect properties, and has important implications for density functional theory development.

In statistical mechanics, the finite size scaling method provides a systematic way to extrapolate information about criticality obtained from a finite system to the thermodynamic limit. For quantum systems, the finite size corresponds not to the spatial dimension but to the number of elements in a complete basis set used to expand the exact wave function of a given Hamiltonian. In this lecture I will discuss how finite size scaling works in quantum mechanics and how to calculate quantum critical parameters for stability of atomic, molecular and quantum dot systems.

X-ray Photoelectron Spectroscopy (XPS), which is known as Electron Spectroscopy for Chemical Analysis (ESCA), is a powerful research tool for the study of the surface of solids. The technique is widely used for studies of the properties of atoms, molecules, solids, and surfaces. The main success of the XPS technique is associated with studies of the physical and chemical phenomena on the surface of solids. These investigations were limited by relatively simple inorganic reactions and not many biologically related objects were approached by XPS. There are impartial reasons for low involvement of XPS into investigations of biologically related objects. In this presentation successful examples of XPS studies of bio-related specimens will be presented. In particular, the systematic XPS investigation of four peptide-silane and peptide- silane hybrid sol-gel thin films prepared under biologically benign conditions will be reported. This work demonstrates a use for XPS to characterized biologically inspired surfaces, providing critical information on peptide coverage on the surface of the materials. The self-assembling layer characterization will be considered on the examples of thiols on Au and aryl diazonium molecules on Si(111).

Our work is in the area of the electronic structure and dynamics of complex processes. We engage in developing new and more powerful theoretical techniques which enable us to describe strong electronic correlation problems. Of particular theoretical interest are the construction of fast (polynomial) algorithms to solve the quantum many-particle problem, and the treatment of correlation in time-dependent processes. A key feature of our theoretical approach is the use of modern renormalization …

This presentation demonstrates how the classical diffusion-capture (D-C) model has improved sensor performance, since the D-C model is a \“geometry of diffusion\” rather than a \“geometry of electrostatics.\” A scaling law based on D-C is also posited; the scaling law resolves many classical puzzles and aids the interpretation of experiments to date with a simple coherent framework.

The scaling of technology has produced exponential growth in transistor development and computing power in the last few decades, but scaling still presents several challenges. These two lectures will cover device aware CMOS design to address power, reliability, and process variations in scaled technologies for different application domains: high-performance with power as constraint and ultra-low power with reasonable performance.

Quantum computers would represent an exponential increase in computing power…if they can be built. This tutorial describes the theoretical background to quantum computing, its potential for several specific applications, and the demanding challenges facing practical implementation. The field currently suffers from a strange imbalance with theoretical advances far outstripping experimental demonstration. The field is poised for a breakthrough that would make quantum circuits experimentally \“accessible\”, as opposed to the million dollar price tags attached to most current implementations.

This talk will highlight several illustrative applications of constrained density functional theory (DFT) to electron transfer dynamics in electronic materials. The kinetics of these reactions are commonly expressed in terms of well known Marcus parameters (driving force, reorganization energy and diabatic coupling) that are often difficult to predict using DFT. We show that constrained DFT provides a practical solution to many of these problems by making the charge on the acceptor an independent natural variable. We use this technique to examine localization/delocalization transitions in molecular wires, spindependent charge recombination in electroluminescent materials and charge transfer dynamics through a molecular junction.

Aggressive scaling of CMOS devices in technology generation has resulted in exponential growth in device performance, integration density and computing power. However, the power dissipated by a silicon chip is also increasing in every generation and emerging as a major bottleneck to technology scaling in nanometer technologies. Hence, analysis and reduction of switching energy in binary logic has drawn significant research interest in recent years.

Scanning Probe Microscopes and their remarkable ability to provide three-dimensional maps of surfaces at the nanometer length scale have arguably been the most important tool in establishing the world-wide emergence of Nanotechnology. In this talk, the fundamental ideas behind the first scanning probe microscope – the Scanning Tunneling Microscope (STM) – will be reviewed. By controlling quantum mechanical electron tunneling, an exquisitely sensitive probe can be built to measure height variations above a surface at the picometer (10 ^-12 m) level. Some of the historically important problems solved by STMs will be discussed and a few of the important design principles required to build an STM will also be outlined.

Computer simulation is now an essential tool for the research and development of semiconductor processes and devices, but to use a simulation tool intelligently, one must know what\‘s \“under the hood.\” This talk is a tutorial introduction designed for someone using semiconductor device simulation for the first time. After reviewing the semiconductor equations, I will briefly describe how one solves them \“exactly\” on a computer. I\‘ll then discuss an example device simulation program and conclude with some thoughts about how to effectively use simulation in practice.

This talk will introduce hierarchical physical models and efficient computational techniques for coupled analysis of electrical, mechanical and van der Waals energy domains encountered in Nanoelectromechanical Systems (NEMS). Numerical results will be presented for several silicon nanoelectromechanical switches to demonstrate the static electromechanical pull-in behavior.

Size quantization is an important effect in modern scaled devices. Due to the cost and limitations of available full quantum approaches, it is appealing to extend semi-classical simulators by adding corrections for size quantization. Monte Carlo particle simulators are good candidates, because a quantum correction potential may simply be added to the standard solution for Poisson equation, with minimal changes in the algorithms. This talk will review and compare the various approaches available for quantum corrections in Monte Carlo simulation. Representative results will include MOS capacitors and ultra-scaled structures like double-gate MOSFET and FinFET.

Atomic Force Microscopy (AFM) is an indispensible tool in nano science for the fabrication, metrology, manipulation, and property characterization of nanostructures. This tutorial reviews some of the physics of the interaction forces between the nanoscale tip and sample, the dynamics of the oscillating tip, and the basic theory of some of the common modes of AFM operation. The tutorial summarizes some of the exciting new applications of Atomic Force Microscopy.