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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 the …
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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 study …
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Excited State Spectroscopy of a Quantum Dot Molecule
11 Jan 2013 | 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 …
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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 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
temperature-insensitivity, …
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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 dot …
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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 wavelength …
