Bulletin of the American Physical Society
Spring 2015 Meeting of the APS New England Section
Volume 60, Number 5
Friday–Saturday, April 24–25, 2015; Boston, Massachusetts
Session D3: 2D Materials |
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Chair: Jason Christopher, Boston University Room: Life Sciences and Engineering Building 304 |
Saturday, April 25, 2015 8:30AM - 8:42AM |
D3.00001: Tunable light-matter interaction and the role of hyperbolicity in graphene-hBN system Anshuman Kumar, Tony Low, Kin Hung Fung, Phaedon Avouris, Nicholas X. Fang Hexagonal boron nitride (hBN) is a natural hyperbolic material which can also accommodate dispersive surface phonon-polariton modes. In this work, we examine theoretically the mid-infrared optical properties of graphene-hBN heterostructures derived from their coupled plasmon-phonon modes. We found that the graphene plasmon couples differently with the phonons of the two Reststrahlen bands, owing to their different hyperbolicity. This also leads to distinctively different interaction between an external quantum emitter and the plasmon-phonon modes in the two bands, leading to substantial modification of its spectrum. The coupling to graphene plasmons allows for additional gate tunability in the Purcell factor, and narrow dips in its emission spectra. [Preview Abstract] |
Saturday, April 25, 2015 8:42AM - 8:54AM |
D3.00002: Strain variation in corrugated graphene Xuanye Wang, Khwanchai Tantiwanichapan, Jason Christopher, Roberto Paiella, Anna Swan Raman spectroscopy is a powerful non-destructive technique for analyzing strain in graphene. Recently there has been interest in making corrugated graphene devices with varying spatial wavelengths \(\Lambda\) for plasmonic and THz applications. Transferring graphene onto corrugated substrates introduces strain, which if there was friction would cause a periodic strain variation. However, the strain variation for spatial period \(\Lambda\) smaller than the diffraction limit \(\lambda\) makes the strain distribution measurement hard. Here we present a detailed study on how strain varies in corrugated graphene with sub-diffraction limit periodicity \(\Lambda\)\(<\)\(\lambda\). Mechanically exfoliated graphene was deposited onto sinusoidal shape silicon dioxide gratings with \(\Lambda\)=400nm period using a ``pick and place'' transfer technique. We observed that the graphene is not rigidly clamped, but partially slides to relieve the strain. We model the linewidth variation to extract the local strain variation as well as the sliding in the presence of charge puddling in graphene. Meanwhile, by tuning the surface salinization, the overall strain as well as its variation could also be tuned. This gives us a better understanding on slippage and strain distribution in corrugated graphene. [Preview Abstract] |
Saturday, April 25, 2015 8:54AM - 9:06AM |
D3.00003: The Effects of Mica Substrate on Exfoliated Molybdenum Disulfide Erin Sutton, Edward George, Kenneth Burch, Marcel Hoek Molybdenum disulfide is a two-dimensional semiconductor which has recently caught a lot of attention due to its 2D behavior and unique electronic and optical properties, emerging as an analogue to graphene with the advantage of a non-zero band gap. MoS2 consists of atomically thin sheets stacked on top of each other and held together by van der Waals forces, which easily allows for interlayer cleaving. However, as-grown MoS2 usually is strongly doped. We wanted to understand the effects the substrate on which the MoS2 is exfoliated has on the crystal's properties. We carefully mechanically exfoliated MoS2 on Mica and Hafnium Oxide substrates, and took Raman and photoluminescence measurements of the exfoliated flakes ranging from 1 layer to 5 layer thicknesses. Obtained results contribute to our understanding of substrate-to-crystal interactions, in addition to the crystal lattice and optical properties of two-dimensional atomic crystals. [Preview Abstract] |
Saturday, April 25, 2015 9:06AM - 9:18AM |
D3.00004: Altering the Optical Properties of Reduced Graphene Oxide by Ozone Treatment Nicholas Lombardo, Caleb Maloney, Katharine Hesse, Anton Naumov Due to its remarkable properties, graphene has found multiple applications in optics and electronics. The advancement of graphene-based optoelectronics is dependent on the ability to controllably produce band gaps in graphene. In this work, controlled ozone treatment of reduced graphene oxide (RGO) in water suspensions was employed in order to functionalize it with oxygen-containing groups, yielding graphene oxide (GO). As a result of such processing, a broad fluorescence feature centered at $\sim$ 532 nm was detected from the product, indicating the formation of the optical band gap in previously non-emissive RGO. The fluorescence intensity could be varied by the ozone treatment time, which provides a possibility of controlled modification of graphene oxide optical properties. Theoretical PM3 modeling of functionalized graphene sheets suggests that such fluorescence could arise due to confinement effects or oxygen group-induced defect states in GO. [Preview Abstract] |
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