Valley splitting in strained silicon quantum wells modeled with 2 degree miscuts, step disorder, and alloy disorder
14 Jan 2008 | Papers | Contributor(s): Neerav Kharche, marta prada, Timothy Boykin, Gerhard Klimeck
Valley splitting (VS) in strained SiGe/Si/SiGe quantum wells grown on (001) and 2° miscut substrates is computed in a magnetic field. Calculations of flat structures significantly overestimate, while calculations of perfectly ordered structures underestimate experimentally observed VS. Step disorder and confinement alloy disorder raise the VS to the experimentally observed levels. Atomistic alloy disorder is identified as the critical physics, which cannot be modeled with analytical effective ...
Atomistic Simulation of Realistically Sized Nanodevices Using NEMO 3-D—Part II: Applications
14 Jan 2008 | Papers | Contributor(s): Gerhard Klimeck, Shaikh S. Ahmed, Neerav Kharche, Marek Korkusinski, Muhammad Usman, marta prada, Timothy Boykin
In part I, the development and deployment of a general nanoelectronic modeling tool (NEMO 3-D) has been discussed. Based on the atomistic valence-force field and the sp3d5s* nearest neighbor tight-binding models, NEMO 3-D enables the computation of strain and electronic structure in nanostructures consisting of more than 64 and 52 million atoms, corresponding to volumes of (110 nm)3 and (101 nm)3, respectively. In this part, successful applications of NEMO 3-D are demonstrated in the atomistic ...
Atomistic Simulation of Realistically Sized Nanodevices Using NEMO 3-D: Part I − Models and Benchmarks
14 Jan 2008 | Papers | Contributor(s): Gerhard Klimeck, Shaikh S. Ahmed, Neerav Kharche, Hansang Bae, Steven Clark, Benjamin P Haley, Maxim Naumov, Hoon Ryu, Faisal Saied, marta prada, Marek Korkusinski, Timothy Boykin
Device physics and material science meet at the atomic scale of novel nanostructured semiconductors, and the distinction between new device or new material is blurred. Not only the quantum-mechanical effects in the electronic states of the device but also the granular atomistic representation of the underlying material are important. Approaches based on a continuum representation of the underlying material typically used by device engineers and physicists become invalid. Ab initio methods used ...
Atomistic Electronic Structure Calculations of Unstrained Alloyed Systems Consisting of a Million Atoms
14 Jan 2008 | Papers | Contributor(s): Gerhard Klimeck, Timothy Boykin
The broadening of the conduction and valence band edges due to compositional disorder in alloyed materials of finite extent is studied using an s p3 s ∗ tight binding model. Two sources of broadening due to configuration and concentration disorder are identified. The concentrational disorder dominates for systems up to at least one million atoms and depends on problem size through an inverse square root law. Significant differences (over 12 meV) in band edge energies are seen depending on ...
Development of a Nanoelectronic 3-D (NEMO 3-D ) Simulator for Multimillion Atom Simulations and Its Application to Alloyed Quantum Dots
14 Jan 2008 | Papers | Contributor(s): Gerhard Klimeck, Timothy Boykin
Material layers with a thickness of a few nanometers are common-place in today’s semiconductor
devices. Before long, device fabrication methods will reach a point at which the other two device
dimensions are scaled down to few tens of nanometers. The total atom count in such deca-nano
devices is reduced to a few million. Only a small finite number of “free” electrons will operate such
nano-scale devices due to quantized electron energies and electron charge. This work demonstrates
Crystal Viewer Tool
22 Dec 2007 | Tools | Contributor(s): Yuanchen Chu, Daniel F Mejia, James Fonseca, Michael Povolotskyi, Gerhard Klimeck
Visualize different crystal lattices and planes
NanoElectronic MOdeling: NEMO
20 Dec 2007 | Online Presentations | Contributor(s): Gerhard Klimeck
This presentation was one of 13 presentations in the one-day forum, "Excellence in Computer Simulation," which brought together a broad set of experts to reflect on the future of computational science and engineering.
Novel nanoelectronic devices such as quantum dots, nanowires, and ultra-scaled quantum wells are expected to significantly enhance existing nanoelectronic technologies. The behavior of carriers and their interaction with their environment need to be fundamentally explained at a ...
Engineering at the nanometer scale: Is it a new material or a new device?
06 Nov 2007 | Online Presentations | Contributor(s): Gerhard Klimeck
This seminar will overview NEMO 3D simulation capabilities and its deployment on the nanoHUB as well as an overview of the nanoHUB impact on the community.
Illinois 2007 Nano-Bio Workshop with nanoHUB Summer School and User Forum
27 Apr 2007 | Workshops | Contributor(s): Narayan Aluru, Eric Jakobsson, Umberto Ravaioli, Dave Mattson, Gerhard Klimeck, Michael McLennan
This summer, on the campus of the University of Illinois, the NCDBN and NCN@UIUC will hold a scientific meeting on "Experimental and Computational Approaches to Understanding Membrane Assemblies and Permeation," a nanoHUB user forum, and a summer school on "Multiscale Theory, Simulation, and Reality at the Nano-Bio Interface" and the nanoHUB. Together, these will create a two-week community for learning, sharing, and doing multiscale simulation with emphasis on applications in biology.
Atomistic Alloy Disorder in Nanostructures
26 Feb 2007 | Online Presentations | Contributor(s): Gerhard Klimeck
Electronic structure and quantum transport simulations are typically performed in perfectly ordered semiconductor structures. Bands and modes are defined resulting in quantized conduction and discrete states. But what if the material is fundamentally disordered? What if the disorder is at the same length scale as the device itself? This presentation will provide an introduction to the intriguing physics of disordered systems in bulk, quantum dots, nanowires, and quantum wells. The general ...
13 Mar 2006 | Tools | Contributor(s): Neophytos Neophytou, Shaikh S. Ahmed, Eric Polizzi, Gerhard Klimeck, Mark Lundstrom
Simulates ballistic transport properties in 3D Carbon NanoTube Field Effect Transistor (CNTFET) devices
13 Mar 2006 | Tools | Contributor(s): M. P. Anantram, Shaikh S. Ahmed, Alexei Svizhenko, Derrick Kearney, Gerhard Klimeck
Simulates ballistic transport in 2D MOSFET devices
14 Dec 2006 | Tools | Contributor(s): Gyungseon Seol, Youngki Yoon, James K Fodor, Jing Guo, Akira Matsudaira, Diego Kienle, Gengchiau Liang, Gerhard Klimeck, Mark Lundstrom, Ahmed Ibrahim Saeed
This tool simulates E-k and DOS of CNTs and graphene nanoribbons.
31 Oct 2006 | Tools | Contributor(s): M. E. Klausmeier-Brown, C. M. Maziar, P. E. Dodd, M. A. Stettler, Xufeng Wang, Gerhard Klimeck
Improved program consists of DEMON and SDEMON
Why is Nanotechnology Multidisciplinary? A perspective of one EE
19 Oct 2006 | Online Presentations | Contributor(s): Gerhard Klimeck
The field of nano science and nano-technology covers broad areas of expertise. Classical fields of Physics, Chemistry, Material Science, Electrical/Mechanical/Chemical Engineering all are involved in the "new" field. Nano research and development is therefore multidisciplinary. This presentation is the personal perspective of an electrical engineer who works in nanoelectronics, beginning with an introductory discussion of nanoelectronics and the formations of a multidisciplinary nano research team. An explanation is given for different length-scales as well as the trend of device size-shrinking. Two resulting multidisciplinary large-scale modeling and simulation efforts are presented: 1) the creation of the first nanoelectronic CAD tool NEMO at Texas Instruments, and 2) the creation and operation of the community simulation web site nanoHUB.org by the Network for Computational Nanotechnology (NCN).
Three-Dimensional Simulations of Field Effect Sensors for DNA Detection
03 Aug 2006 | Online Presentations | Contributor(s): Eddie Howell, Gerhard Klimeck
Here, the development of a DNA field-effect transistor (DNAFET) simulator is described. In DNAFETs the gate structure of a silicon on insulator (SOI) field-effect transistor is replaced by a layer of immobilized single-stranded DNA molecules which act as surface probe molecules. When complementary DNA strands bind to the receptors, the charge distribution near the surface of the device changes, modulating current transport through the device and enabling detection Arrays of DNAFETs can be used for detecting single-nucleotide polymorphisms and for DNA sequencing. The advantage of DNAFETs over optical methods of detection is that DNAFETs allow direct, label-free operation. The simulator constructs the specified DNA molecules and calculates the electrostatic potential due to the partial charges of the DNA molecules by solving the three-dimensional Poisson-Boltzmann equation. The resulting data demonstrate how the specifications of the device affect its level of sensitivity. Further collaborations with experimentalists in the field will lead to further advances in medicine.
Investigation of the Electrical Characteristics of Triple-Gate FinFETs and Silicon-Nanowire FETs
08 Aug 2006 | Online Presentations | Contributor(s): Monica Taba, Gerhard Klimeck
Electrical characteristics of various Fin field-effect transistors (FinFETs) and silicon-nanowires were analyzed and compared using a modified three-dimensional self-consistent quantum-mechanical simulator in order to investigate device performance. FinFETs have been proposed to fulfill the requirement of the semiconductor road map as old devices are reaching their scaling limits. It can be expected to be manufactured in a conventional CMOS process, whereas an ideal silicon-nanowire, although it has better performance, is difficult to manufacture. Simulations with different fin dimensions were done and compared to the ideal nanowire FinFET to analyze their electrical characteristics. As a result, the FinFET device can be the optimal structure with characteristics comparable to the silicon nanowire.
NEMO 3D: Intel optimizations and Multiple Quantum Dot Simulations
03 Aug 2006 | Online Presentations | Contributor(s): Anish Dhanekula, Gerhard Klimeck
NEMO-3D is a nanoelectronic modeling tool that analyzes the electronic structure of nanoscopic devices. Nanoelectronic devices such as Quantum Dots (QDs) can contain millions of atoms,. Therefore, simulating their electronic structure, can take up to several days. In order to simulate and analyze such devices in a time efficient manner one needs to use the most advanced computing technology available to date. This paper discusses the methods and technologies used to implement changes in NEMO 3D in order to save computing time. Intel’s SSE 3 instruction set, also known as PNI (Prescott New instruction set), was used to tweak NEMO 3D in order to enhance its performance on the most advanced processors. The Hamlet cluster, consisting of 32 bit Intel processors, was used as a benchmark and the changes were tested on the Lear cluster, comprising of 64-bit Intel processors. Inputs describing quantum devices containing up to 48 million atoms were used to test the changes with the above mentioned systems. From the experiments only a 3-10 % improvement was noticed on the inputs tested. The results were sent to Intel for rechecking, and they were sent back after a problem was found and fixed. The new results showed an improvement of 24% in the electronic structure calculations. This implies that optimizations can be made to the strain calculations for further improvements in performance.
19 May 2006 | Tools | Contributor(s): Hong-Hyun Park, Lang Zeng, Matthew Buresh, Siqi Wang, Gerhard Klimeck, Saumitra Raj Mehrotra, Clemens Heitzinger, Benjamin P Haley
Simulate 3D nanowire transport in the effective mass approximation with phonon scattering and 3D Poisson self-consistent solution
Band Structure Lab
19 May 2006 | Tools | Contributor(s): Samik Mukherjee, Kai Miao, Abhijeet Paul, Neophytos Neophytou, Raseong Kim, Junzhe Geng, Michael Povolotskyi, Tillmann Christoph Kubis, Arvind Ajoy, Bozidar Novakovic, James Fonseca, Hesameddin Ilatikhameneh, Sebastian Steiger, Michael McLennan, Mark Lundstrom, Gerhard Klimeck
Computes the electronic and phonon structure of various materials in the spatial configuration of bulk , quantum wells, and wires
06 Apr 2006 | Tools | Contributor(s): Akira Matsudaira, Saumitra Raj Mehrotra, Shaikh S. Ahmed, Gerhard Klimeck, Dragica Vasileska
Capacitance of a MOS device
30 Mar 2006 | Tools | Contributor(s): Shaikh S. Ahmed, Saumitra Raj Mehrotra, SungGeun Kim, Matteo Mannino, Gerhard Klimeck, Dragica Vasileska, Xufeng Wang, Himadri Pal, Gloria Wahyu Budiman
Simulates the current-voltage characteristics for bulk, SOI, and double-gate Field Effect Transistors (FETs)
30 Mar 2006 | Tools | Contributor(s): Dragica Vasileska, Shaikh S. Ahmed, Gokula Kannan, Matteo Mannino, Gerhard Klimeck, Mark Lundstrom, Akira Matsudaira, Junzhe Geng
SCHRED simulation software calculates the envelope wavefunctions and the corresponding bound-state energies in a typical MOS, SOS and a typical SOI structure.
12 Jan 2006 | Tools | Contributor(s): Mark R. Pinto, kent smith, Muhammad A. Alam, Steven Clark, Xufeng Wang, Gerhard Klimeck, Dragica Vasileska
2D/3D devices under steady state, transient conditions or AC small-signal analysis
How Can Your Educational Modules Contain Interactive Online Simulation?
28 Feb 2005 | Online Presentations | Contributor(s): Gerhard Klimeck
The Network for Computational Nanotechnology (NCN) is a multi-university, NSF-funded
initiative with a mission to lead in research, education, and outreach to students and professionals,
while at the same time deploying a unique web-based cyber-infrastructure to serve the nation''s National Nanotechnology Initiative. The primary NCN outreach vehicle is the nanoHUB, our
web site found at http://nanoHUB.org. The nanoHUB currently provides interactive online
simulation and educational resources such as tutorials, seminars, and online courses. In 2004
alone, over 3,200 users explored our educational and outreach resources. Over 1,000 users
performed some 60,000 on-line simulations. The raw web-page hit count exceeded 3.7 million.
The nanoHUB provides access to about 30 research codes, ranging from toy-models to
sophisticated simulation engines. Users can access these codes on their own desktop through any
standard web browser, with no special setup or installation requirements. The NCN provides the
resource for models, simulation and computation free of charge and reach a broad audience.