
Nanoelectronic Modeling Lecture 17: Introduction to RTDs  Relaxation Scattering in the Emitter
27 Jan 2010  Online Presentations  Contributor(s): Gerhard Klimeck
Realistic RTDs will have nonlinear electrostatic potential in their emitter. Typically a triangular well is formed in the emitter due to the applied bias and the emitter thus contains discrete quasi bound states.

Nanoelectronic Modeling Lecture 16: Introduction to RTDs  Realistic Doping Profiles
27 Jan 2010  Online Presentations  Contributor(s): Gerhard Klimeck
Realistic RTDs need extremely high doping to provide enough carriers for high current densities. However, Impurity scattering can destroy the RTD performance. The dopants are therefore typically spaced 20100nm away from the central double barrier structure.

Nanoelectronic Modeling Lecture 14: Open 1D Systems  Formation of Bandstructure
27 Jan 2010  Online Presentations  Contributor(s): Gerhard Klimeck, Dragica Vasileska
The infinite periodic structure Kroenig Penney model is often used to introduce students to the concept of bandstructure formation. It is analytically solvable for linear potentials and shows critical elements of bandstructure formation such as core bands and different effective masses in different bands.

Nanoelectronic Modeling Lecture 12: Open 1D Systems  Transmission through Double Barrier Structures  Resonant Tunneling
27 Jan 2010  Online Presentations  Contributor(s): Gerhard Klimeck, Dragica Vasileska
This presentation shows that double barrier structures can show unity transmission for energies BELOW the barrier height, resulting in resonant tunneling. The resonance can be associated with a quasi bound state, and the bound state can be related to a simple particle in a box calculation.

Nanoelectronic Modeling Lecture 09: Open 1D Systems  Reflection at and Transmission over 1 Step
25 Jan 2010  Online Presentations  Contributor(s): Gerhard Klimeck, Dragica Vasileska, Samarth Agarwal
One of the most elemental quantum mechanical transport problems is the solution of the time independent Schrödinger equation in a onedimensional system where one of the two half spaces has a higher potential energy than the other. The analytical solution is readily obtained using a scattering matrix approach where wavefunction amplitude and slope are matched at the interface between the two halfspaces. Of particular interest are the wave/particle injection from the lower potential energy halfspace.

Nanoelectronic Modeling Lecture 08: Introduction to Bandstructure Engineering II
25 Jan 2010  Online Presentations  Contributor(s): Gerhard Klimeck
This presentation provides a brief overview of the concepts of bandstructure engineering and its potential applications to light detectors, light emitters, and electron transport devices. Critical questions of the origin of bandstructure and its dependence on local atom arrangements are raised to create awareness of the need of atomistic materials and device models at the nanometer scale.

Nanoelectronic Modeling Lecture 07: Introduction to Bandstructure Engineering I
25 Jan 2010  Online Presentations  Contributor(s): Gerhard Klimeck
This presentation serves as a reminder about basic quantum mechanical principles without any real math. The presentation reviews critical properties of classical systems that can be described as particles, propagating waves, standing waves, and chromatography.

Nanoelectronic Modeling Lecture 06: nanoHUB.org  Rappture Toolkit
25 Jan 2010  Online Presentations  Contributor(s): Gerhard Klimeck, Michael McLennan
The rapid deployment of over 150 simulation tools in just over 4 years has been enabled by 2 critical software developments: 1) Maxwell’s Daemon: a middleware that can deploy at a production level UNIX based codes in web browsers, and 2) Rappture: a software system that enables the rapid development of graphical user interfaces and data management to new and legacy softwares.

Nanoelectronic Modeling Lecture 05: nanoHUB.org  Impact on Research
25 Jan 2010  Online Presentations  Contributor(s): Gerhard Klimeck
Impact on research is often measured by the number of publications in the scientific literature. The nanoHUB support team has identified 430 citations to nanoHUB.org and/or nanoHUB tools and seminars in the time frame leading up to May 2008 the 430 citations in the scientific literature. 52% of these papers are authored by persons outside of the Network for Computational Nanotechnology (NCN) which created and hosts nanoHUB.org. Social network of usage and collaboration are developing and documented in social network maps. nanoHUB.org can show usage on nanoHUB and subsequent publications and several testimonials of research use are given. Use by experimentalists can be demonstrated through publications and through testimonials.

Nanoelectronic Modeling Lecture 04: nanoHUB.org  Impact on Education
25 Jan 2010  Online Presentations  Contributor(s): Gerhard Klimeck
This presentation will provide a few highlights of how nanoHUB.org is being used in education and what kind of impact it has had so far. Tools and seminars are indeed being used as instructional materials. nanoHUB has been used in over 290 classes in the past few years in over 90 institutions for class room instruction. New developments are under way to provide onestopshops for toolpowered classes / curricula, which aggregate tools, homework assignments, and other teaching materials into one single resource.

Nanoelectronic Modeling Lecture 03: nanoHUB.org  Online Simulation and More
25 Jan 2010  Online Presentations  Contributor(s): Gerhard Klimeck
This presentation provides a brief overview of the nanoHUB capabilites, compares it to static web page delivery, highlights its technology basis, and provides a vision for future cyberinfrastructures in a system of federated HUBs powered by the HUBzero.org infrastructure.

Nanoelectronic Modeling Lecture 02: (NEMO) Motivation and Background
25 Jan 2010  Online Presentations  Contributor(s): Gerhard Klimeck, Dragica Vasileska
Fundamental device modeling on the nanometer scale must include effect of open systems, high bias, and an atomistic basis. The nonequilibrium Green Function Formalism (NEGF) can include all these components in a fundamentally sound approach and has been the basis for a few novel device simulation tools.

Nanoelectronic Modeling Lecture 01: Overview
25 Jan 2010  Online Presentations  Contributor(s): Gerhard Klimeck
The goal of this series of lectures is to explain the critical concepts in the understanding of the stateoftheart modeling of nanoelectronic devices such as resonant tunneling diodes, quantum wells, quantum dots, nanowires, and ultrascaled transistors. Three fundamental concepts critical to the understanding of nanoelectronic devices will be explored: 1) open systems vs. closed systems, 2) nonequilibrium systems vs. closetoequilibrium systems, and 3) atomistic material representation vs. continuum matter representation.

Nanoelectronic Modeling Lecture 11: Open 1D Systems  The Transfer Matrix Method
31 Dec 2009  Online Presentations  Contributor(s): Gerhard Klimeck, Dragica Vasileska, Samarth Agarwal, Parijat Sengupta
The transfer matrix approach is analytically exact, and “arbitrary” heterostructures can apparently be handled through the discretization of potential changes. The approach appears to be quite appealing. However, the approach is inherently unstable for realistically extended devices which exhibit electrostatic band bending or include a large number of basis sets.

Nanoelectronic Modeling Lecture 10: Open 1D Systems  Transmission through & over 1 Barrier
31 Dec 2009  Online Presentations  Contributor(s): Gerhard Klimeck, Dragica Vasileska, Samarth Agarwal
Tunneling and interference are critical in the understanding of quantum mechanical systems. The 1D time independent Schrödinger equation can be easily solved analytically in a scattering matrix approach for a system of a single potential barrier. The solution is obtained by matching wavefunction values and derivatives at the two interfaces in the spatial domain. This simple example shows the extended nature of wavefunctions, the nonlocal effects of local potential variations, the formation of resonant states through interference, and quantum mechanical tunneling in its simplest form.

Your Career Choices after Graduate School and The MostNeglected Item in your Career Development
23 Oct 2009  Online Presentations  Contributor(s): Gerhard Klimeck
What are your career choices after graduate school? Will you develop technology yourself? Will you work in a team? Will you guide people? Where will you work: in industry, research lab, or academia? Regardless where you work, there is generally one item that you are not being taught in graduate school: your communication skills. Come and hear my personal perspective on working in Industry (Texas Instruments) for 4 years, in a U.S. government research laboratory (NASA JPL) for 6 years and in an academic institution (Purdue University) for over 5 years.

Comparison of PCPBT Lab and Periodic Potential Lab
10 Aug 2009  Online Presentations  Contributor(s): Abhijeet Paul, Samarth Agarwal, Gerhard Klimeck, Junzhe Geng
This small presentation provides information about the comparison performed for quantum wells made of GaAs and InAs in two different tools. This has been done to benchmark the results from completely two different sets of tools and validate the obtained results. In this presentation we provide the motivation for this work, the input details and results obtained. The tools used for this purpose are Piecewise Constant Potential Barrier Tool(PCPBT) and Periodic Potential Lab. We provide ...

BNC Research Review: nanoHUB.org: Future Cyberinfrastructure Serving a Community of 60,000 Today
01 May 2008  Online Presentations  Contributor(s): Gerhard Klimeck
This presentation is part of a collection of presentations describing the projects, people, and capabilities enhanced by research performed in the Birck Center, and a look at plans for the upcoming year.

Why QuaMC 2D and ParticleBased Device Simulators?
02 May 2008  Online Presentations  Contributor(s): Dragica Vasileska, Shaikh S. Ahmed, Gerhard Klimeck
We describe the need for particlebased device simulators when modeling nanoscale devices.

Examples for QuaMC 2D particlebased device Simulator Tool
10 May 2008  Online Presentations  Contributor(s): Dragica Vasileska, Shaikh S. Ahmed, Gerhard Klimeck
We provide three examples that demonstrate the full capabilities of QuaMC 2D for alternative device technologies.

Ensemble Monte Carlo Method Described
27 Apr 2008  Online Presentations  Contributor(s): Dragica Vasileska, Gerhard Klimeck, Mark Lundstrom, David K. Ferry
In this presentation we give an overview of the implementation details of the Ensemble Monte Carlo method for mobility and drift velocity calculation in arbitrary materials and arbitrary crystalographic orientations.NSFCareer, ONR

ParticleBased Device Simulators Description
28 Apr 2008  Online Presentations  Contributor(s): Dragica Vasileska, Shaikh S. Ahmed, Gerhard Klimeck
In this presentation we give an overview of partclebased device simulations with focus on implementation details.

nanoHUB.org: Future Cyberinfrastructure Serving a Community of 60,000 Today
23 Apr 2008  Online Presentations  Contributor(s): George B. Adams III, Gerhard Klimeck, Mark Lundstrom, Michael McLennan
nanoHUB.org provides users with "fingertip access" to over 70 simulation tools for research and education. Users not only launch jobs that are executed on the stateoftheart computational facilities of Open Science Grid and TeraGrid, but also interactively visualize and analyze the results—all via an ordinary web browser. nanoHUB middleware hides the complexity of Grid computing, handling authentication, authorization, file transfer, and visualization, and letting the researcher focus ...

Introduction to Quantum Dot Lab
31 Mar 2008  Online Presentations  Contributor(s): Sunhee Lee, Hoon Ryu, Gerhard Klimeck
The nanoHUB tool "Quantum Dot Lab" allows users to compute the quantum mechanical "particle in a box" problem for a variety of different
confinement shapes, such as boxes, ellipsoids, disks, and pyramids. Users can explore, interactively, the energy spectrum and orbital shapes of new quantized states, as well as quickly view these artificial atoms have their own particular optical absorption properties. This presentation introduces the particle in the box problem in 1D and 3D, and explores the concept of occupied and empty states, allowed transitions, and optical absorption. Students are encouraged to duplicate all the simulation results shown in the presentation. Exercises and a project or homework assignment are given at the end of the presentation.

Nanoelectronic Modeling: Multimillion Atom Simulations, Transport, and HPC Scaling to 23,000 Processors
07 Mar 2008  Online Presentations  Contributor(s): Gerhard Klimeck
Future field effect transistors will be on the same length scales as “esoteric” devices such as quantum dots,
nanowires, ultrascaled quantum wells, and resonant tunneling diodes. In those structures the behavior of
carriers and their interaction with their environment need to be fundamentally explained at a quantum
mechanical level. Modeling efforts that are targeted to enhance the theoretical understanding of these
devices are underway worldwide. Most of these device level descriptions utilize an effective mass
approach which ignores any details of the atomic granularity. However, the concepts of device and
material meet at the nanometer scale. The new device is really a new material and vice versa. A
representation of the constituent materials at the atomic resolution is needed to quantitatively model
devices with a countable number of atoms. While atomistic representations are novel to device physicists,
the concept of finite devices that are not infinitely periodic is novel in the semiconductor materials
modeling community. This presentation will provide a perspective of the NEMO 1D and NEMO 3D tool
developments, their scaling on advanced computational resources up to 23,000 processors, their impact on
the understanding of nanoelectronic devices, and the need for continued algorithm work.