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08 Jun 2010 | Contributor(s): David K. Ferry, Dragica Vasileska, Gerhard Klimeck
In mineralogy and crystallography, a crystal structure is a unique arrangement of atoms in a crystal. A crystal structure is composed of a basis, a set of atoms arranged in a particular way, and a lattice. The basis is located upon the points of a lattice spanned by lattice vectors, which is an...
Tight-Binding Band Structure Calculation Method
08 Jun 2010 | Contributor(s): Dragica Vasileska, Gerhard Klimeck
This set of slides describes on simple example of a 1D lattice, the basic idea behind the Tight-Binding Method for band structure calculation.
This is a manual for the Piece-Wise Constant Potential Barrier Tool.
Worked Examples for a PN Diode
01 Jun 2010 | Contributor(s): Dragica Vasileska, Gerhard Klimeck
several worked examples are presented that illustrate the operation of a PN diode.
InAs: Evolution of iso-energy surfaces for heavy, light, and split-off holes due to uniaxial strain.
25 May 2010 | Contributor(s): Abhijeet Paul, Denis Areshkin, Gerhard Klimeck
Movie was generated using Band Structure Lab tool at nanoHUB and allows to scan over four parameters:Hole energy measured from the top of the corresponding band (i.e. the origin of energy scales for LH and SOH is different)Strain direction: , , Carrier type: LH, HH, SOHStrain...
Nanotechnology Animation Gallery
22 Apr 2010 | Teaching Materials | Contributor(s): Saumitra Raj Mehrotra, Gerhard Klimeck
Animations and visualization are generated with various nanoHUB.org tools to enable insight into nanotechnology and nanoscience. Click on image for detailed description and larger image download. Additional animations are also available Featured nanoHUB tools: Band Structure Lab. Carrier...
Fermi-Dirac statistics with temperature
15 Apr 2010 | Animations | Contributor(s): Saumitra Raj Mehrotra, Gerhard Klimeck
Fermi-Dirac statistics is applied to identical particles with half-integer spin (such as electrons) in a system that is in thermal equilibrium. Since particles are assumed to have negligible mutual interactions, this allows a multi-particle system to be described in terms of single-particle...
Diffusion of holes and electrons
Diffusion is a process of particles distributing themselves from regions of high- to low- concentrations. In semi-classical electronics these particles are the charge carriers (electrons and holes). The rate at which a carrier can diffuse is called diffusion constant with units of cm2/s. The...
CV profile with different oxide thickness
20 Apr 2010 | Animations | Contributor(s): Saumitra Raj Mehrotra, Gerhard Klimeck
C-V (or capacitance-voltage) profiling refers to a technique used for the characterization of semiconductor materials and devices. C-V testing is often used during the characterization process to determine semiconductor parameters, particularly in MOSCAP and MOSFET structures.C-V measurements...
Electronic band structure
12 Apr 2010 | Animations | Contributor(s): Saumitra Raj Mehrotra, Gerhard Klimeck
In solid-state physics, the electronic band structure (or simply band structure) of a solid describes ranges of energy in which an electron is "forbidden" or "allowed". The band structure is also often called the dispersion or the E(k) relationship. It is a mathematical relationship between the...
Graphene nanoribbon bandstructure
17 Apr 2010 | Animations | Contributor(s): Saumitra Raj Mehrotra, Gerhard Klimeck
Graphene nanoribbons (often abbreviated as GNR) are planar strips of graphene with a thickness of approximately one atom. Carbon atoms in graphene are sp2-hybridized with a carbon-carbon bond length of approximately 0.142 nm. As an electronic material, graphene exhibits many desirable...
Carbon nanotube bandstructure
22 Apr 2010 | Animations | Contributor(s): Saumitra Raj Mehrotra, Gerhard Klimeck
Carbon nanotubes are allotropes of carbon with a cylindrical nanostructure, and can be categorized into single-walled nanotubes (SWNT) and multi-walled nanotubes (MWNT). These cylindrical carbon molecules have novel properties that make them potentially useful in many nanotechnology...
In quantum mechanics the time-independent Schrodinger's equation can be solved for eigenfunctions (also called eigenstates or wave-functions) and corresponding eigenenergies (or energy levels) for a stationary physical system. The wavefunction itself can take on negative and positive values and...
Threshold voltage in a nanowire MOSFET
22 Apr 2010 | Animations | Contributor(s): Saumitra Raj Mehrotra, SungGeun Kim, Gerhard Klimeck
Threshold voltage in a metal oxide semiconductor field-effect transistor (better known as a MOSFET) is usually defined as the gate voltage at which an inversion layer forms at the interface between the insulating layer (oxide) and the substrate (body) of the transistor. A MOSFET is said to be...
Local density of states
The concept of general density of states (DOS) in devices is, by definition, spatially invariant. However, in the case of inhomogeneous materials or in quantum confined structures, the density of states can be resolved in space. This is known as local density of states, or LDOS. …
Resonant Tunneling Diode operation
A resonant tunneling diode (RTD) is a type of diode with a resonant tunneling structure that allows electrons to tunnel through various resonant states at certain energy levels. RTDs can be fabricated using many different types of materials (such as III-V, type IV, II-VI semiconductors) and...
PN junction in forward bias
A PN junction is formed by joining p-type and n-type doped semiconductors together in very close contact. The p- and n-type semiconductors are conducting because of the available free carriers. However, because the carriers diffuse into the adjoining p and n regions by a process called...
Graphene is a one-atom-thick planar sheet of sp2-bonded carbon atoms that are densely packed in a honeycomb crystal lattice. Graphene sheets are weakly bonded to other graphene layers above and below to form Graphite. The difference between two layers is approximately 0.335 nm .Graphite can...
16 Apr 2010 | Animations | Contributor(s): Saumitra Raj Mehrotra, Gerhard Klimeck
A fullerene is any molecule composed entirely of carbon, and can take the form of hollow spheres, ellipsoids, or tubes. Spherical fullerenes (often referred to as "buckyballs") are one of the known structurally different form of carbon. C60 are the most common of buckyball structures. …
Nanoelectronic Modeling Lecture 29: Introduction to the NEMO3D Tool
04 Aug 2010 | Online Presentations | Contributor(s): Gerhard Klimeck
This presentation provides a very high level software overview of NEMO3D. The items discussed are:Modeling Agenda and MotivationTight-Binding Motivation and basic formula expressionsTight binding representation of strainSoftware structureNEMO3D algorithm flow NEMO3D parallelization scheme –...
Nanoelectronic Modeling Lecture 28: Introduction to Quantum Dots and Modeling Needs/Requirements
20 Jul 2010 | Online Presentations | Contributor(s): Gerhard Klimeck
This presentation provides a very high level software overview of NEMO1D.Learning Objectives:This lecture provides a very high level overview of quantum dots. The main issues and questions that are addressed are:Length scale of quantum dotsDefinition of a quantum dotQuantum dot examples and...
Nanoelectronic Modeling Lecture 27: NEMO1D -
09 Mar 2010 | Online Presentations | Contributor(s): Gerhard Klimeck
This presentation provides a very high level software overview of NEMO1D. The items discussed are:User requirementsGraphical user interfaceSoftware structureProgram developer requirementsDynamic I/O design for batch and GUIResonance finding algorithmInhomogeneous energy meshingInformation flow,...
Nanoelectronic Modeling Lecture 26: NEMO1D -
NEMO1D demonstrated the first industrial strength implementation of NEGF into a simulator that quantitatively simulated resonant tunneling diodes. The development of efficient algorithms that simulate scattering from polar optical phonons, acoustic phonons, alloy disorder, and interface...
Nanoelectronic Modeling Lecture 25b: NEMO1D - Hole Bandstructure in Quantum Wells and Hole Transport in RTDs
Heterostructures such as resonant tunneling diodes, quantum well photodetectors and lasers, and cascade lasers break the symmetry of the crystalline lattice. Such break in lattice symmetry causes a strong interaction of heavy-, light- and split-off hole bands. The bandstructure of holes and the...
Nanoelectronic Modeling Lecture 25a: NEMO1D - Full Bandstructure Effects
07 Jul 2010 | Online Presentations | Contributor(s): Gerhard Klimeck
(quantitative RTD modeling at room temperature)