Bulletin of the American Physical Society
Annual Meeting of the Four Corners Section of the APS
Volume 55, Number 9
Friday–Saturday, October 15–16, 2010; Ogden, Utah
Session L2: Condensed Matter, Nano II |
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Chair: David Allred, Brigham Young University Room: 404A |
Saturday, October 16, 2010 1:30PM - 1:42PM |
L2.00001: Ab Initio Study of Interaction between Boron and Nitrogen Dopants in Graphene Nabil Al-Aqtash, Igor Vasiliev We study the interactions between doping boron (B) and nitrogen (N) atoms in graphene. Our calculations are carried out using density functional theory combined with the generalized gradient approximation for the exchange-correlation functional. The total energies, equilibrium geometries, electronic charge distributions, and densities of states of doped graphene sheets are examined in cases of B-B, N-N, and B-N co-doped graphene. The interaction energy between two doping atoms is found to be inversely proportional to the square of the separation distance. We find the B-B and N-N interactions to be repulsive and the B-N interaction to be attractive. The changes in the density of states observed in B- and N-doped graphene are explained in terms of electronic charge transfer. [Preview Abstract] |
Saturday, October 16, 2010 1:42PM - 1:54PM |
L2.00002: Photoluminescent Lifetime Measurements of Indium Gallium Arsenide Quantum Dot Structures Using Time-Correlated Single Photon Counting Scott Thalman, John Colton, Haeyeon Yang We will be presenting the results of time-resolved photoluminesence measurements performed on self-assembled InGaAs quantum dot samples. The samples were grown by molecular beam epitaxy and annealed at high temperatures with some samples potentially forming quantum dot chains. Lifetimes were measured using the technique of ``time-correlated single photon counting'' (TCSPC). With a 30 fs pulsed Ti:Sapphire laser, a silicon avalanche photodiode detector and an Ortec fast digitizer we were able to achieve time resolution of 100 ps. After deconvoluting the measured data with our instrument response function, lifetimes of 0.6-0.9 ns were obtained. [Preview Abstract] |
Saturday, October 16, 2010 1:54PM - 2:06PM |
L2.00003: Photoluminescent properties of InGaAs quantum dot structures Kenneth Clark, John Colton, Matt Guerron, Dallas Smith, Scott Thalman, Haeyeon Yang Quantum dots are promising candidates for use in optical-electronic applications such as near infrared detectors and light sources. They have also been suggested for future use in quantum computers. We have been studying quantum dot and quantum dot chain samples, which were grown using a variation of the Stranski--Krastanov ``self-assembled'' method. We have used photoluminescence (PL) spectroscopy to studies these samples, examining the existence of quantum dots/chains, and determining the optical quality of the samples. I will be presenting our ongoing investigations of a series of such samples. [Preview Abstract] |
Saturday, October 16, 2010 2:06PM - 2:18PM |
L2.00004: Partial Graphene Growth on Copper By Chemical Vapor Deposition Caleb Hustedt The successful growth of large-area, mono-layer graphene films has the potential to revolutionize applications of graphene in electronic and mechanical devices. Recently, CVD growth has been used to realize such films on metal surfaces. Unfortunately, defects in the graphene cause decreased mechanical and electrical properties. In our study we examine the growth process of CVD graphene on copper. We examined the structure of graphene at its individual nucleation sites by partial graphene growth. We found that graphene growth has significant differences on varying copper surfaces. [Preview Abstract] |
Saturday, October 16, 2010 2:18PM - 2:30PM |
L2.00005: A Calculation of the Electronic Structure of Gallium Phosphide Nanotubes Peter Lyon, Bret Hess We studied the band structure and density of states of both zigzag and armchair gallium phosphide nanotubes using density functional theory with a quantum chemistry program called VASP. We were able to show that all gallium phosphide nanotubes are narrow band-gap semiconductors. We have also shown that all zigzag nanotubes have indirect band gaps and that all armchair nanotubes have direct band gaps. Furthermore, we calculated that increasing the radius of armchair nanotubes led to a decrease in the band gap but that there was no similar change in the band gap of zigzag nanotubes as radius increased. [Preview Abstract] |
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