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Quantum dots can be produced in a variety of material systems and geometries. This simple educational tool simulates the particle in a box problem for a variety of geometries such as boxes, cylinders, pyramids, and ellipsoids. A simple single band effective mass model is employed and the simulations run interactively. 3-D visualization depicts the 3-D confined wave functions. Optical transitions are computed and sorted into dark and light lines. Absorption curves are computed for different polarizations and orientations. Parameters such as incident light angle and polarization, Fermi level, or temperature can be scanned to analyze the effect of 3-D geometries on isotropic optical properties.
This tool is supported by variety of different materials:
A First time user guide A general tutorial entitled “Quantum Dots” on the origin of quantum mechanics and the interpretation of quantum dots as artificial atoms. An introductory tutorial to the tool “Introduction to Quantum Dot Lab” with usage scenarios on state filling, light/dark absorption lines, and absorption coefficients. A homework / project assignment entitled “Homework Exercise on Quantum Dot Spectra, Absorption, and State Symmetry”.
A topic page is available with homeworks/tests/real-life problems.
Upgrades from previous versions:
Ver 1.1: Now users can select an effective mass of the quantum dot. Also the tool speed was a bit improved and there is a status bar indicating progress in the visualization preparation – which had been slow.
Ver 1.1.1: The optical absorption lines are not as finely resolved and therefore do not demand such large file sizes. The default absorption line width was also increased by a factor of 10. Finally the number of allowed states was increased to 150.
Ver 1.1.4: Added default values for effective mass for the different materials listed.
Ver 2.0: The tool now runs NEMO 5 instead of NEMO 3D. This fixes a problem connected to the absolute position of energy levels. A 1s tight-binding band structure model is used which is equivalent to an effective-mass model. The optical matrix elements and absorption peaks are calculated slightly differently compared to the old tool. The GUI has been rearranged, allowing for the effective mass parameters to be set by the user. The tab for optical calculations has also been cleaned up. The performance of NEMO 5 is still undergoing optimizations.
Ver 2.0.1/2: 4 digits of floating point is used in energy states plot. Fixed error when the different number of states is used. Several detailed description of input parameters is updated.
Ver 2.1: Update to NEMO 5 r4228.
Quantum Dot Lab version 1.x ran NEMO-3D. Starting from version 2.0, the underlying engine is NEMO 5, a code under development in the research group of Gerhard Klimeck. NEMO 5 is an open source nanoelectronics device simulator containing a variety of different material and geometry models. Features include the construction of atomistic grids of varying crystal structures, multiband Schroedinger-Poisson simulations, and user-friendly input/output.
|Sebastian Steiger, Michael Povolotskyi, Tillmann Kubis, Hong-Hyun Park:||NEMO 5 core development team.|
|Lars Bjaalie:||Integration of NEMO 5 with Quantum Dot Lab.|
|Matteo Mannino, David Ebert, Michael McLennan:||Initial version of Quantum Dot Lab (<2.0).|
|Gerhard Klimeck:||General supervision.|
Researchers should cite this work as follows:
- "Building and Deploying Community Nanotechnology Software Tools on nanoHUB.org and Atomistic simulations of multimillion-atom quantum dot nanostructures", Gerhard Klimeck, Marek Korkusinski, Haiying Xu, Seungwon Lee, Sebastien Goasguen and Faisal Saied, Proceedings of the 5th IEEE Conference on Nanotechnology, 2: pg. 807, 07 (2005)