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Why quantum dot simulation domain must contain multi-million atoms?
11 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...
Quantum Dot based Photonic Devices
01 Apr 2012 | Online Presentations | Contributor(s): Muhammad Usman
Deployment of nanometer-sized semiconductor quantum dots (QDs) in the active region ofphotonic devices such as lasers, semiconductor optical amplifiers (SOA's), photo-detectors etc.for the next generation communication systems offers unique characteristics such astemperature-insensitivity, high...
Excited State Spectroscopy of a Quantum Dot Molecule
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,...
Electronic Structure Theory of Dilute Impurity Alloys: GaBiP and GaBiAs
18 Jan 2013 | 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...
Polarization Response of Multi-layer InAs Quantum Dot Stacks
25 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...
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...