Nanotechnology Survey with ANTSY
This nanoHUB “topic page” provides an easy access to selected nanoHUB Education Material that is openly accessible and usable by everyone around the world.
We invite you to participate in this open source, interactive educational initiative:
- Contribute your content by uploading it to the nanoHUB. (See “Contribute Content”) on the nanoHUB mainpage.
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- Finally, let us know what you are doing and your suggestions improving the nanoHUB by using the “Feedback” section, which you can find under “Support“
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Crystal Structures, Lattices, Silicon, Bucky Balls
The Crystal Viewer in ANTSY tool enables the interactive visualization different Bravais lattices, and crystal planes, and materials (diamond, Si, InAs, GaAs, graphene, buckyball). It is supported by homework assignment in MS Word and Adobe PDF format.
Carbon nanotubes and graphene ribbons made of the single element carbon have attracted significant interest in the nanotechnology research community. The CNTbands tool in ANTSY allows students to visualize the material geometries and study the electronic structure of these materials.
Additional Lectures / Learning Modules:
Individual quantum dots can be created from two-dimensional electron or hole gases present in remotely doped quantum wells or semiconductor heterostructures. The sample surface is coated with a thin layer of resist. A lateral pattern is then defined in the resist by electron beam lithography. This pattern can then be transferred to the electron or hole gas by etching, or by depositing metal electrodes (lift-off process) that allow the application of external voltages between the electron gas and the electrodes. Such quantum dots are mainly of interest for experiments and applications involving electron or hole transport, i.e., an electrical current. The energy spectrum of a quantum dot can be engineered by controlling the geometrical size, shape, and the strength of the confinement potential. Also in contrast to atoms it is relatively easy to connect quantum dots by tunnel barriers to conducting leads, which allows the application of the techniques of tunneling spectroscopy for their investigation. Confinement in quantum dots can also arise from electrostatic potentials (generated by external electrodes, doping, strain, or impurities).
Quantum Dot Lab in ANTSY computes the eigenstates of a particle in a box of various shapes including domes and pyramids.
- Quantum Dots is a nano 101, introductory lecture that starts from particle-wave duality and explores the concepts of quantum dots
- Introduction to Quantum Dot Lab (by the author of the tool)
- Quantum Dot Spectra, Absorption, and State Symmetry: an Exercise (by the author of the tool)
- Quantum Dot Lab Learning Module: An Introduction
The Piece-Wise Constant Potential Tool in ANTSY allows calculation of the transmission and the reflection coefficient of arbitrary five, seven, nine, eleven and 2n-segment piece-wise constant potential energy profile. For the case of multi-well structure it also calculates the quasi-bound states so it can be used as a simple demonstration tool for the formation of energy bands. Also, it can be used in the case of stationary perturbation theory exercises to test the validity of, for example, the first order and the second order correction to the ground state energy of the system due to small perturbations of, for example, the confining potential. The Piece-Wise Constant Potential Tool in ANTSY can also be used to test the validity of the WKB approximation for triangular potential barriers.
- Quantum-Mechanical Reflections: an Exercise
- Double-Barrier Case: An Exercise
- From 1 well to 2 wells to 5 wells to periodic potentials: an Exercise
- Energy Bands as a Function of the Geometry of the n-Well Potential: an Exercise
- Cosine Bands: an Exercise for PCPBT
- Quantum-Mechanical Reflections in Nanodevices: an Exercise
- Tunneling Through Triangular Barrier: an Exercise for PCPBT
- Stationary Perturbation Theory: an Exercise for PCPBT
Put a potential barrier in the path of electrons, and it will block their flow. But if the barrier is thin enough, electrons can tunnel right through due to quantum mechanical effects. Even more surprising, if two or more thin barriers are placed closely together, electrons will bounce between the barriers, and at certain resonant energies, flow right through the barriers as if they were not there! Check out the Resonant Tunneling Diode Lab in ANTSY lab, which lets you control the number of barriers and their material properties, and then simulate current as a function of bias. Devices exhibit a surprising negative differential resistance, even at room temperature! Run this tool online, right in your web browser! View a demo of this tool in action.
About ANTSY Constituent Tools
The Assembly of Basic Applications for Coordinated Understanding of Semiconductors (ANTSY) has been put together from individual disjoint tools to enable educators and students to have a one-stop-shop in semiconductor education. It therefore benefits tremendously from the hard work that the contributors of the individual tool builders have put into their tools.
As a matter of credit, simulation runs that are performed in the ANTSY tool are also credited to the individual tools, which help the ranking of the individual tools. We do also count the number of usages of the individual tools in the ANTSY tool set, to measure the ANTSY impact and possibly also improve the tool.
In the description above we do not refer to the individual tools since we want to guide the users to the composite ANTSY tool. We cite the individual tools here explicitly so they are being given the appropriate credit and on their rspective tool pages are being linked to this ANTSY topic page.
Additional Reading and Tools
ADEPT is not supported within ANTSY, since it is a research-oriented tool that enables the study of solar cells for various material systems. A Reference Manual and a ADEPT Heterostructure Tutorial are available. The interface is not a simple point-and-click interface as for example the PN junction lab, but simulation commands are entered in a command-like fashion.
MOS Capacitors with Quantum Corrections
(Image(/images/tool/schred/schred.jpg, 120 class=align-right) failed - File not found) Schred is not formally supported in ANTSY. It contains more advanced quantum mechanical concepts and is a nanoHUB contributed tool. It calculates the envelope wavefunctions and the corresponding bound-state energies in a typical MOS (Metal-Oxide-Semiconductor) or SOS (Semiconductor-Oxide-Semiconductor) structure and a typical SOI structure by solving self-consistently the one-dimensional (1D) Poisson equation and the 1D Schrodinger equation.
- Schred: Exercise 1
- SCHRED: Exercise 2
- Schred: Exercise 3
- Quantum Size Effects and the Need for Schred
- Schred Tutorial Version 2.1
madFETs – more Field Effect Transistors
The Field-Effect-Transistor has been proposed and implement in many physical systems, materials, and geometries. A multitude of acronyms have developed around these concepts. The “Many-Acronym-Device-FET” or “madFET” was born. The author of this document was able to trace an attribute to the acronym madFET from Bill Frensley to Herbert Kroemer.
nanoHUB.org hosts a variety of tools that enable the simulation of field effect transisors for a variety of different geometries in a variety of different levels of approximations. There is a madFETs topics page that provides an overview of many of the nanoHUB.org madFET tools.
Technology Computer Aided Design – TCAD
Once students have mastered the basics of semiconductors they may be quite interested in venturing into TCAD. There is a topics page for aTCADlab and associated single aTCADlab tool that assembles various TCAD tools available on the nanoHUB. Process, device, and circuit simulation is represented in aTCADlab.