This presentation demonstrates the OMEN capabilities to perform a multi-scale simulation of advanced InAs-based high mobility transistors.Learning Objectives:Quantum Transport Simulator Full-Band and Atomistic III-V HEMTs Performance Analysis Good Agreement with Experiment Some Open Issues Outlook Improve Models (Contact) Investigate Scaling of Gate Length Scattering?

This presentation the effects of line edge roughness on graphene nano ribbon (GNR) transitors..Learning Objectives:GNR TFET Simulation pz Tight-Binding Orbital Model 3D Schrödinger-Poisson Solver Device Simulation Structure Optimization (Doping, Lg, VDD) LER => Localized Band Gap States LER => Performance Deterioration Outlook and Challenges Ripples Scattering More Accurate Bandstructure Model Dissipative Scattering (Electron-Phonon)

This presentation discusses the motivation for band-to-band tunneling transistors to lower the power requirements of the next generation transistors. The capabilities of OMEN to model such complex devices on an atomistic representation is demonstrated.Learning Objectives:Band-To-Band Tunneling Transistors may be “better” than a superscaled MOSFET because: The subthreshold swing is possibly smaller than the ideal 60mV/dec in the best case MOSFET – i.e the device …

This presentation discusses the consequences of Alloy Disorder in unstrained strained AlGaAs nanowiresRelationship between dispersion relationship and transmission in perfectly ordered wiresBand folding in Si nanowiresTranmisison in disordered wires – relationship to an approximate bandstructreReminder of the origin of bandstructure and bandstructure engineeringLocalization of wavefunctionsLearning Objectives:Alloy wires are NOT smooth“Conduction band edge” flucatuates locallyDispersion changes Transmission and Density of states show localization effects

This presentation discusses the consequences of Alloy Disorder in strained InGaAs Quantum Dots Reminder of the origin of bandstructure and bandstructure engineeringWhat happens when there is disorder?Concept of disorder in the local bandstructureConfiguration noise, concentration noise, clusteringLearning Objectives:Device-to-device fluctuations in nanostructures may be significant even if the shape and size of the quantum dots remain perfectly controlled.Configuration noise, concentration noise and clustering in perfectly size and shape controlled quantum dots can lead to optical transition fluctuations that should be experimentally relevant.

This presentation discusses disorder in AlGaAs unstrained systems in bulk. Bandstructure of an ideal simple unit cellWhat happens when there is disorder?Concept of a supercellBand folding in a supercellBand extraction from the concept of approximate bandstructureComparison of alloy disorder with the virtual crystal approximationConfiguration noise, concentration noiseHow large does an alloy supercell have to be? When does the “bulk” condition occur?Learning Objectives:Bandedges and bandgaps are influenced by: Placement / configuration disorderConcentration noise Clustering System size is very important “bulk” starts at 100,000 atoms=> Nanostructures are not “bulk” => like quantum dots, nanowires, and quantum wells vary locally

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 of the quantum dots. The role of the non-linear strain behavior ovserved in the experimental data is explored in NEMO3D. The simulation engine serves as a virtual microscope to understand the interplay of disorder, strain, and quantum dot shape.Learning Objectives:Objective:Optical emission at 1.5μm without GaNUnderstand experimental data on QD spectra in selective overgrowthApproach: Model large structure60nm x 60nm x 60nm9 million atomsNo changes to the published tight binding parametersResult:Match experiment remarkably well Strain change in quantum dot aspect ratio Quantitative model of complex systemStudied sensitivity to experimental imperfections – small variationsEffective mass theories provided the wrong guidance

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 systemLearning Objectives:Strain is the source of the creation of the InAs QDs on GaAsStrain is a long range phenomenonStrain reaches further vertically than horizontallyQuantum dots will grow on top of each otherElectron wavefunctions are confined to the central quantum dots and can be computed in a smaller domain

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 – original 1D spatial decompositionNEMO3D scaling on parallel computes from the year 2000 til 2007New 1D, 2D, and 3D spatial decomposition scheme and parallel performance52 million atom simulation demonstrationLearning Objectives:Convey a broad overview of the NEMO3D simulation engine. Student shall learn about the algorithmic coponents of geometry construction, atom position computaion, and electronic structure calculation.Student shall learn the need and usefulness of parallel computers to solve the NEMO3D problems.Student shall learn a demonstration of a software capability and validation.

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 ApplicationsSingle electronicsNeed for quantum dot modelingModel requirements – what are the physical effects that need to be included?Overview of some of the existing theories and modelsTight binding approach