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Eiffel tower

A view of molecular electron wavefunction through atomistic geometry of a QD bilayer; (red=In atoms, green=Ga atoms, blue=As atoms); Read full article at nanotechweb

      Muhammad Usman

          Tyndall National Institute
          University College Cork
          Lee Maltings, Dyke Parade
          Cork Ireland
          Email: usman (at) alumni (dot) purdue (dot) edu

        Education & Affiliations:

          Ph.D. Electrical Engineering, July 2010
          Purdue University, West Lafayette, Indiana, USA.

          M.Sc. Electrical Engineering, May 2005
          University of Engineering & Technology, Lahore, Pakistan.

          B.Sc. (Honors & Distinction) Electrical Engineering, April 2003
          University of Engineering & Technology, Lahore, Pakistan.

I am a member of the American Physical Society (APS), Material Research Society (MRS), IEEE, Network for Computational Nanotechnology (NCN), and Purdue Alumni Association.


Some of my talks are available online (users served by 1/15/2013 are 1525):

[Video] Quantum Dot based Photonic Devices @ Physics Department, Dartmouth College, New Hampshire, USA

[Audio] Multi-layer QD Stacks for SOAs @ 3rd International Workshop on Epitaxial Growth and Fundamental Properties of Semiconductor Nanostructures, Austria

[Audio] Excited State Spectroscopy of a Bilayer QD Molecule @ Electrical & Computer Engineering Department, University of Iowa, Iowa, USA

[Audio] Theory of Bismide Alloys @ 2nd International Workshop on Bismuth containing Semiconductors, Surrey University, UK

[Audio] Why QD Simulations Must Contain Multi-Million Atoms?  

[PDF] PhD Research Summary @ Purdue University, Indiana, USA

[PDF] Quantum Dots - My PhD Thesis @ Purdue University, Indiana, USA


Keywords:

Multi-Scale Modeling; Condensed Matter Physics; Atomistic Modeling; III-V Materials; Semiconductor Heterostructures; High Performance Computing; NEMO 3-D; Optoelectronic Devices; Valence Force Field Model; Tight Binding Theory; Quantum Dots; Electronic Structure and Quantum Transport Calculations in Nanoscale Devices; Quantum Mechanics; Novel Bismuth based Alloys; Electronic Structure of Disordered Semiconductors; Theory of Iso-electronic Impurities;

Research Interests:





















I work in multi-disciplinery area of research involving rigorous knowledge of nano-electronics, condensed-matter physics, computational physics, etc. Overall, I am interested in all aspects of light matter interaction. My research work is aimed at improving the efficiency of the energy-conversion devices (photovoltaics), wavelength and polarization engineering by studying novel nano-materials for telecomm and infra-red range devices, and quantum information science in coupled quantum dot systems.

More specifically, I work on the theory, modeling, and simulation of semiconductor materials, their alloys, and low-dimensional devices.

My past and ongoing research efforts are motivated to seek answers for the following questions:

  • Can we design efficient photonic devices from quantum dots? How can we engineer QD parameters to tune output wavelength and polarization for a desired operation?

  • How can bismuth (Bi) based alloys such as GaBiNAs, InGaBiAs, etc. help to realize highly efficient telecomm wavelength devices with reduced temperature sensitivity and supressed Auger losses?

  • How to implement qubit operation in a coupled quantum dot system via coherent manipulation of the trapped charges or spin?

  • To understand and resolve efficiency impeding mechanisms in nanomaterial based photovoltaics to realize sustainable, ecnomical, efficient, and green energy solutions

  • My theory and modeling work is based on the following methods:

  • Strain energy minimization by using atomistic valence force field method.

  • Electronic structure calculations based on twenty/ten bands sp3d5s*/sp3s* Tight Binding method, 14 bands k.p models, DFT.

  • Optical transition strengths from the Fermi's Golden Rule.

  • Linear and quadratic piezoelectric potentials by solving the Poisson's equation.

  • Many-body excitonic spectra by Hartree-Fock (HF) Approximation, Configuration Interaction (CI) approach

  • The detials about these methods are presented here: Modeling Methodologies   

    My current and past experimental collaborators are at:



    I want to acknowledge support from the following organizations:






                                                  Last updated: August 2012, (best viewed in chrome browser), copyright © Muhammad Usman, all rights reserved.