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ABACUS Tool Suite and Bandstructure and Band Models (Fall 2023)
22 Aug 2023 | | Contributor(s):: Gerhard Klimeck
In the third session, Dr. Klimeck will give a brief overview of ABACUS and demonstrate several bandstructure tools. With these, students can explore the Standard Periodic Potential aka Kronig-Penney model as well as bandstructure formation by transmission through finite barriers....
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ABACUS Bandstructure Models (Spring 2022)
05 May 2022 | | Contributor(s):: Gerhard Klimeck
In the third session, Dr. Klimeck will give a brief overview of ABACUS and demonstrate several bandstructure tools. With these, students can explore the Standard Periodic Potential aka Kronig-Penney model as well as bandstructure formation by transmission through finite barriers....
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ABACUS Bandstructure Models (Winter 2021)
21 Dec 2021 | | Contributor(s):: Gerhard Klimeck
In the third session, Dr. Klimeck will give a brief overview of ABACUS and demonstrate several bandstructure tools. With these, students can explore the Standard Periodic Potential aka Kronig-Penney model as well as bandstructure formation by transmission through finite barriers...
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IWCN 2021: How to Preserve the Kramers-Kronig Relation in Inelastic Atomistic Quantum Transport Calculations
15 Jul 2021 | | Contributor(s):: Daniel Alberto Lemus, James Charles, Tillmann Christoph Kubis
The nonequilibrium Green’s function method (NEGF) is often used to predict quantum transport in atomically resolved nanodevices. This yields a high numerical load when inelastic scattering is included. Atomistic NEGF had been regularly applied on nanodevices, such as nanotransistors....
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IWCN 2021: Interfacial Trap Effects in InAs Gate-all-around Nanowire Tunnel Field- Effect Transistors: First-Principles-Based Approach
15 Jul 2021 | | Contributor(s):: Hyeongu Lee, SeongHyeok Jeon, Cho Yucheol, Mincheol Shin
In this work, we investigated the effects of the traps, Arsenic dangling bond (AsDB) and Arsenic anti-site (AsIn) traps, in InAs gate-all-around nanowire TFETs, using the trap Hamiltonian obtained from the first-principles calculations. The transport properties were treated by nonequilibrium...
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IWCN 2021: Ab initio Quantum Transport Simulation of Lateral Heterostructures Based on 2D Materials: Assessment of the Coupling Hamiltonians
14 Jul 2021 | | Contributor(s):: Adel Mfoukh, Marco Pala
Lateral heterostructures based on lattice-matched 2D materials are a promising option to design efficient electron devices such as MOSFETs [1], tunnel-FETs [2] and energy-filtering FETs [3]. In order to rigorously describe the transport through such heterostructures, an ab-initio approach based...
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IWCN 2021: Thermoelectric Properties of Complex Band and Nanostructured Materials
14 Jul 2021 | | Contributor(s):: Neophytos Neophytou, Patrizio Graziosi, Vassilios Vargiamidis
In this work, we describe a computational framework to compute the electronic and thermoelectric transport in materials with multi-band electronic structures of an arbitrary shape by coupling density function theory (DFT) bandstructures to the Boltzmann Transport Equation (BTE).
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Atomistic Green’s Functions: The Beauty of Self-energies
28 Oct 2020 | | Contributor(s):: Tillmann Christoph Kubis
This presentation gives an introduction to NEGF. It will be explained how self-energies cause NEGF to fundamentally differ from most other quantum methods. Atomistic examples of phonon and impurity scattering self-energies agree quantitatively with experiments.
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Bandstructure Effects in Nano Devices With NEMO: from Basic Physics to Real Devices and to Global Impact on nanoHUB.org
08 Mar 2019 | | Contributor(s):: Gerhard Klimeck
This presentation will intuitively describe how bandstructure is modified at the nanometer scale and what some of the consequences are on the device performance.
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NEMO5, a Parallel, Multiscale, Multiphysics Nanoelectronics Modeling Tool: From Basic Physics to Real Devices and to Global Impact on nanoHUB.org
10 Nov 2016 | | Contributor(s):: Gerhard Klimeck
The Nanoelectronic Modeling tool suite NEMO5 is aimed to comprehend the critical multi-scale, multi-physics phenomena and deliver results to engineers, scientists, and students through efficient computational approaches. NEMO5’s general software framework easily includes any kind of...
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NEMO5, a Parallel, Multiscale, Multiphysics Nanoelectronics Modeling Tool
19 Sep 2016 | | Contributor(s):: Gerhard Klimeck
The Nanoelectronic Modeling tool suite NEMO5 is aimed to comprehend the critical multi-scale, multi-physics phenomena and deliver results to engineers, scientists, and students through efficient computational approaches. NEMO5’s general software framework easily includes any kind of...
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Atomistic Modeling of Nano Devices: From Qubits to Transistors
13 Apr 2016 | | Contributor(s):: Rajib Rahman
In this talk, I will describe such a framework that can capture complex interactions ranging from exchange and spin-orbit-valley coupling in spin qubits to non-equilibrium charge transport in tunneling transistors. I will show how atomistic full configuration interaction calculations of exchange...
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Self-energies: Opening Doors for Nanotechnology
07 Apr 2016 | | Contributor(s):: Tillmann Christoph Kubis
In this talk, it will be shown how the concept of self-energies can be used to interface all these fields into the same nanotechnology modeling framework. Self-energies are most commonly used in the quantum transport method of nonequilibrium Green’s functions (NEGF). The NEGF method is...
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Phonon Interactions in Single-Dopant-Based Transistors: Temperature and Size Dependence
25 Nov 2015 | | Contributor(s):: Marc Bescond, Nicolas Cavassilas, Salim Berrada
IWCE 2015 presentation. in this work we investigate the dependence of electron-phonon scattering in single dopant-based nanowire transistor with respect to temperature and dimensions. we use a 3d real-space non-equilibrium green': ; s function (negf) approach where electron-phonon...
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Mode Space Tight Binding Model for Ultra-Fast Simulations of III-V Nanowire MOSFETs and Heterojunction TFETs
13 Nov 2015 | | Contributor(s):: Aryan Afzalian, Jun Huang, Hesameddin Ilatikhameneh, Santiago Alonso Perez Rubiano, Tillmann Christoph Kubis, Michael Povolotskyi, Gerhard Klimeck
IWCE 2015 presentation. we explore here the suitability of a mode space tight binding algorithm to various iii-v homo- and heterojunction nanowire devices. we show that in iii-v materials, the number of unphysical modes to eliminate is very high compared to the si case previously reported...
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Density Functional Tight Binding (DFTB) Modeling in the Context of Ultra-Thin Silicon-on-Insulator MOSFETs
10 Oct 2015 | | Contributor(s):: Stanislav Markov
IWCE 2015 presentation. We investigate the applicability of density functional tight binding (DFTB) theory [1][2], coupled to non-equilibrium Green functions (NEGF), for atomistic simulations of ultra-scaled electron devices, using the DFTB+ code [3][4]. In the context of ultra-thin...
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Non-Equilibrium Green's Function (NEGF): A Different Perspective
18 Sep 2015 | | Contributor(s):: Supriyo Datta
The NEGF method was established in the 1960’s through the classic work of Keldysh and others [1] using the methods of many- body perturbation theory (MBPT) and this approach is widely used in the literature [2]. By contrast I have introduced a different approach starting with the...
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Tutorial 4a: High Bias Quantum Transport in Resonant Tunneling Diodes
29 Mar 2011 | | Contributor(s):: Gerhard Klimeck
Outline:Resonant Tunneling Diodes - NEMO1D: Motivation / History / Key InsightsOpen 1D Systems: Transmission through Double Barrier Structures - Resonant TunnelingIntroduction to RTDs: Linear Potential DropIntroduction to RTDs: Realistic Doping ProfilesIntroduction to RTDs: Relaxation Scattering...
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Lecture 3: Introduction to NEGF
08 Sep 2010 | | Contributor(s):: Supriyo Datta
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Nonequilibrium Green’s functions theory: Transport and optical gain in THz quantum cascade lasers
26 Mar 2010 | | Contributor(s):: Tillmann Christoph Kubis
Quantum cascade lasers (QCLs) are promising sources of coherent THz radiation. However, state of the art THz-QCLs are still limited to cryogenic temperatures. The charge transport in these QCLs is subject to coherent quantum phenomena, such as quantum tunneling, confinement and interferences as...