Nanoelectronic Modeling Lecture 32: Strain Layer Design through Quantum Dot TCAD
04 Aug 2010 | Online Presentations | Contributor(s): Gerhard Klimeck, Muhammad Usman
This presentation demonstrates the utilization of NEMO3D to understand complex experimental data of embedded InAs quantum dots that are selectively overgrown with a strain reducing InGaAs layer. Different alloy concentrations of the strain layer tune the optical emission and absorption wavelength...
Nanoelectronic Modeling Lecture 31a: Long-Range Strain in InGaAs Quantum Dots
04 Aug 2010 | Online Presentations | Contributor(s): Gerhard Klimeck
This presentation demonstrates the importance of long-range strain in quantum dotsNumerical analysis of the importance of the buffer around the central quantum dot - local band edges – vertical and horizontal extension of the bufferControlled overgrowth can tune the electron energies in the...
Nanoelectronic Modeling Lecture 29: Introduction to the NEMO3D Tool
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 roughness...
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)
Nanoelectronic Modeling Lecture 24: NEMO1D - Incoherent Scattering
Incoherent processes due to phonons, interface roughness and disorder had been suspected to be the primary source of the valley current of resonant tunneling diodes (RTDs) at the beginning of the NEMO1D project in 1994. The modeling tool NEMO was created at Texas Instruments to fundamentally...
Nanoelectronic Modeling Lecture 23: NEMO1D - Importance of New Boundary Conditions
One of the key insights gained during the NEMO1D project was the development of new boundary conditions that enabled the modeling of realistically extended Resonant Tunneling Diodes (RTDs). The new boundary conditions are based on the partitioning of the device into emitter and collector...
Nanoelectronic Modeling Lecture 22: NEMO1D - Motivation, History and Key Insights
07 Feb 2010 | Online Presentations | Contributor(s): Gerhard Klimeck
The primary objective of the NEMO-1D tool was the quantitative modeling of high performance Resonant Tunneling Diodes (RTDs). The software tool was intended for Engineers (concepts, fast turn-around, interactive) and Scientists (detailed device anaysis). Therefore various degrees of...
Nanoelectronic Modeling Lecture 21: Recursive Green Function Algorithm
The Recursive Green Function (RGF) algorithms is the primary workhorse for the numerical solution of NEGF equations in quasi-1D systems. It is particularly efficient in cases where the device is partitioned into reservoirs which may be characterized by a non-Hermitian Hamiltonian and a central...
Nanoelectronic Modeling Lecture 20: NEGF in a Quasi-1D Formulation
27 Jan 2010 | Online Presentations | Contributor(s): Gerhard Klimeck, Samarth Agarwal, Zhengping Jiang
This lecture will introduce a spatial discretization scheme of the Schrödinger equation which represents a 1D heterostructure like a resonant tunneling diode with spatially varying band edges and effective masses.
Nanoelectronic Modeling Lecture 19: Introduction to RTDs - Asymmetric Structures
27 Jan 2010 | Online Presentations | Contributor(s): Gerhard Klimeck
This lecture explores this effect in more detail by targeting an RTD that has a deliberate asymmetric structure. The collector barrier is chosen thicker than the emitter barrier. With this set-up we expect that the tunneling rate into the RTD from the emitter is faster than the tunneling rate...
Nanoelectronic Modeling Lecture 18: Introduction to RTDs - Quantum Charge Self-Consistency (Hartree)
In this semi-classical charge and potential model the quantum mechanical simulation is performed once and the quantum mechanical charge is in general not identical to the semi-classical charge.
Nanoelectronic Modeling Lecture 17: Introduction to RTDs - Relaxation Scattering in the Emitter
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
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 20-100nm 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...
Nanoelectronic Modeling Lecture 12: Open 1D Systems - Transmission through Double Barrier Structures - Resonant Tunneling
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 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...
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...
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 one-dimensional 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...
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...
Nanoelectronic Modeling Lecture 07: Introduction to Bandstructure Engineering I
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...