Atomistic Simulation of Realistically Sized Nanodevices Using NEMO 3-D—Part II: Applications
14 Jan 2008 | Publications | Contributor(s): Gerhard Klimeck, Shaikh S. Ahmed, Neerav Kharche, Marek Korkusinski, Muhammad Usman, marta prada, Timothy Boykin
In part I, the development and deployment of a general nanoelectronic modeling tool (NEMO 3-D) has been discussed. Based on the atomistic valence-force field and the sp3d5s* nearest neighbor tight-binding models, NEMO 3-D enables the computation of strain and electronic structure in nanostructures …
Electronic Structure Theory of Dilute Impurity Alloys: GaBiP and GaBiAs
28 Oct 2011 | Online Presentations | Contributor(s): M. Usman
We report an atomistic model established for electronic structure calculations of GaBiAs (0 < Bi < 12%) alloys based on empirical tight binding parameters. Alloy supercells consisting of 1000 and 8000 atoms are relaxed using valence force field (VFF) method, including anharmonic corrections to the …
Excited State Spectroscopy of a Quantum Dot Molecule
16 Dec 2011 | Online Presentations | Contributor(s): Muhammad Usman
Atomistic electronic structure calculations are performed to study the coherent inter-dot couplings of the electronic states in a single InGaAs quantum dot molecule. The experimentally observed excitonic spectrum by Krenner et al (Phys. Rev. Lett. 94 057402, 2005) is quantitatively reproduced, and …
Nanoelectronic Modeling Lecture 32: Strain Layer Design through Quantum Dot TCAD
07 Jul 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 …
NEMO3D User Guide for Quantum Dot Simulations
29 Nov 2011 | Publications | Contributor(s): M. Usman, Gerhard Klimeck
NEMO 3D is a large and complex simulator; and understanding of its source code requires considerable knowledge of quantum mechanics, condensed matter theory, and parallel programming.
Polarization Response of Multi-layer InAs Quantum Dot Stacks
20 Oct 2011 | Online Presentations | Contributor(s): Muhammad Usman
Recent experimental measurements, without any theoretical guidance, showed that isotropic polarization response can be achieved by increasing the number of QD layers in a QD stack. In this work, we analyse the polarization response of multi-layer quantum dot stacks containing up to nine quantum dot …
Quantitative Modeling and Simulation of Quantum Dots
16 Jul 2010 | Presentation Materials | Contributor(s): Muhammad Usman
Quantum dots grown by self-assembly process are typically constructed by 50,000 to 5,000,000 structural atoms which confine a small, countable number of extra electrons or holes in a space that is comparable in size to the electron wavelength. Under such conditions quantum dots can be interpreted …
Quantum Dot based Photonic Devices
19 Mar 2012 | Online Presentations | Contributor(s): Muhammad Usman
Deployment of nanometer-sized semiconductor quantum dots (QDs) in the active region of
photonic devices such as lasers, semiconductor optical amplifiers (SOA's), photo-detectors etc.
for the next generation communication systems offers unique characteristics such as
Self-Assembled Quantum Dot Structure (pyramid)
01 Feb 2011 | Animations | Contributor(s): Gerhard Klimeck, Insoo Woo, Muhammad Usman, David S. Ebert
Pyramidal InAs Quantum dot. The quantum dot is 27 atomic monolayers wide at the base and 15 atomic monolayers tall.
Self-Assembled Quantum Dot Wave Structure
31 Jan 2011 | Animations | Contributor(s): Gerhard Klimeck, Insoo Woo, Muhammad Usman, David S. Ebert
A 20nm wide and 5nm high dome shaped InAs quantum dot grown on GaAs and embedded in InAlAs is visualized.
Why quantum dot simulation domain must contain multi-million atoms?
04 Jan 2013 | Online Presentations | Contributor(s): Muhammad Usman
The InGaAs quantum dots obtained from the self-assembly growth process are heavily strained. The long-range strain and piezoelectric fields significantly modifies the electronic structure of the quantum dots. This imposes a critical constraint on the minimum size of the simulation domain to study …