Bulletin of the American Physical Society
APS March Meeting 2014
Volume 59, Number 1
Monday–Friday, March 3–7, 2014; Denver, Colorado
Session M30: Focus Session: Graphene Devices: Fabrication, Characterization and Modeling: Sensing using 2D Materials |
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Sponsoring Units: DMP Chair: Aldo Migone, Southern Illinois University Room: 605 |
Wednesday, March 5, 2014 11:15AM - 11:27AM |
M30.00001: Controlled healing of graphene nanopore Konstantin Zakharchenko, Alexander Balatsky Graphene is often mentioned as a promising material for nanopores applications in DNA sequencing, sensory, biosensoring and molecular detectors. We will present realistic computer simulation studies of regrowth and healing of graphene nanopores of different sizes ranging from $30$ to $5$~\AA. Our simulations clearly point to at least two distinct healing mechanisms of graphene sheet: one so called edge attachment mechanism, where carbons are attached to the edges of graphene sheet and second, the direct insertion mechanism, that involves atom insertion directly into a sheet of graphene even in the absence of the edges. Insertion mechanism is a suprising prediction that points to the growth process that would be operational even in the pristine graphene. We have uncovered an unusual dependence in the speed of nanopores regrowth and structure of ``healed'' areas as function of its size in the wide range of temperatures. Our findings point a significantly more complicated pathways for graphene annealing. They also provide an important enabling step in development of graphene based devices for numerous nanotechnology applications. [Preview Abstract] |
Wednesday, March 5, 2014 11:27AM - 11:39AM |
M30.00002: Hybrid graphene nanoribbon-nanopore devices for biomolecule detection and DNA sequencing Adrian Balan, Matthew Puster, Julio Alejandro Rodriguez- Manzo, Marija Drndic We present a study of hybrid graphene nanoribbon-nanopore devices for biomolecule detection and ultimately DNA sequencing. We realized back or side gated devices comprised of nanopores(2$-$10 nm) at the edge or in the center of GNRs with widths of 5-200nm, on SiNx membranes. Electron beam-induced irradiation effects[1] are studied by in situ conductance measurements during nanopore formation inside a 200kV transmission electron microscope (TEM) for different doping levels. Bases on our findings we devise a scanning TEM procedure which prevent the GNR electron induced damage, enabling sensitive biosensors. We finally present the operation of this sensor for biomolecule detection and DNA sequencing. The higher current ($\mu $A) driven through a GNR compared to the ionic current(nA) in nanopore devices leads to a hundredfold increase in the measuring bandwidth(10-100MHz), possibly enabling DNA sequencing without slowing the molecules. [1] Towards sensitive graphene nanoribbon-nanopore devices by preventing electron beam induced damage. M. Puster, J. A. Rodriguez- Manzo, A. Balan, M. Drndic. ACS Nano,10.1021/nn405112m. [Preview Abstract] |
Wednesday, March 5, 2014 11:39AM - 11:51AM |
M30.00003: Graphene Trans-Electrode Membranes Aaron Kuan, Lu Bo, Ryan Rollings, Don Dressen, Daniel Branton, Jene Golovchenko We report an electrical study of suspended single-layer graphene membranes separating reservoirs of electrolyte solution. Because the opposing reservoirs are separated only by an atomically thin membrane, the trans-conductance (ionic current response to a voltage across the membrane) is extremely sensitive to nanoscale defects in the membrane. This sensitivity allows the precise examination and characterization of intrinsic defects in graphene membranes, as well as engineered defects for devices. We will discuss methods for creating single nanopores or distributed defects in our graphene membranes, with the applications of nanopore DNA sequencing and water desalination in mind. [Preview Abstract] |
Wednesday, March 5, 2014 11:51AM - 12:03PM |
M30.00004: ABSTRACT WITHDRAWN |
Wednesday, March 5, 2014 12:03PM - 12:15PM |
M30.00005: Evidence for Stochastic Switching of Transport through Molecular-Sieving Graphene Membranes Luda Wang, Lee Drahushuk, Steven Koenig, Xinghui Liu, Michael Strano, J. Bunch Two dimensional materials represent an emerging class of gas transport membranes capable of ultrahigh fluxes with molecular sieving potential. Herein, we study gas transport through atomically thin, monolayer graphene membranes open with a single (or several) molecularly sized, sub-nm pores by ozone activation and UV etching. We provide the first evidence for stochastic switching of permeance states through such membranes made from monolayer graphene during CO$_{\mathrm{2}}$~transport. This switching is analyzed using a Hidden Markov Model to estimate the activation barriers of switching. Further evidence is provided using gold clusters formed on the surface of the graphene. Such clusters migrate and partially block the pore upon laser heating in vacuum. This work represents the first example of controlling gas phase transport through molecularly sized pores. [Preview Abstract] |
Wednesday, March 5, 2014 12:15PM - 12:27PM |
M30.00006: ABSTRACT WITHDRAWN |
Wednesday, March 5, 2014 12:27PM - 1:03PM |
M30.00007: to be determined by you Invited Speaker: Alan Johnson |
Wednesday, March 5, 2014 1:03PM - 1:15PM |
M30.00008: Modification of electrical transport properties of graphene field effect devices due to electron-mediated molecular adsorption Sung Oh Woo, Winfried Teizer We study graphene field effect transistor devices that have been exposed to electron beam irradiation. Upon irradiation in vacuum, the Dirac point shifted to negative gate voltage, and in-situ electrical transport measurements indicate the emergence of gate voltage hysteresis of the graphene devices. Both the Dirac point and the hysteresis revert towards their pre-irradiation status over the course of a few days when the graphene is maintained under vacuum. Once the irradiated devices are exposed to ambient air, the original Dirac point was recovered within two hours and the hysteresis disappeared. However, transport properties were not fully recovered but instead degraded depending on electron dosage. In addition, as a result of the irradiation the Raman `D' band, which is an indication of defect generation, emerged and its intensity increased with increasing electron dosage. In addition, we investigated the adsorbate on graphene by atomic force microscopy. The state of the adsorbate on graphene was observed to change with electron dosage indicating that redox coupling is a likely cause of both the Raman defect signal as well as the scattering centers that deteriorate the transport properties. [Preview Abstract] |
Wednesday, March 5, 2014 1:15PM - 1:27PM |
M30.00009: Ab initio energetics, kinetics, and quantum transport characteristics of graphene nanoribbons as nanosensors for detecting nitrogen dioxide Amir A. Farajian, Kirti K. Paulla, Ahmed J. Hassan, Cory R. Knick Molecules adsorption on graphene nanoribbons (GNRs) can be used to engineer and make use of their properties for applications such as energy storage and sensors. We investigate adsorption characteristics by considering nitrogen dioxide as a sample molecule for assessing nanosensor functionality of GNRs. Using ab initio modeling, energetics of various adsorption possibilities are determined and their rate constants are calculated and compared. Nonbonding and weak sp3 adsorptions at the hydrogen-terminated edges are shown to be more feasible than center adsorptions. This shows increased reactivity compared to graphene. Calculated quantum transport responses upon molecules adsorption indicate possibility of sensing extremely low nitrogen dioxide concentrations. Possible approaches for improving gas nanosensor functionality of GNRs are discussed. Reference: RSC Advances, 2013, DOI: 10.1039/c3ra46372a. [Preview Abstract] |
Wednesday, March 5, 2014 1:27PM - 1:39PM |
M30.00010: Patterning, Characterization and Chemical Sensing Applications of Graphene Nanoribbon Arrays Down to 5 nm Using Helium Ion Beam Lithography Ahmad Abbas, Gang Liu, Bilu liu, Luyao Zhang, He Liu, Douglas Ohlberg, Wei Wu, Chongwu Zhou Bandgap engineering of graphene is an essential step towards employing graphene in electronic and sensing applications. Recently, graphene nanoribbons (GNRs) were used to create a bandgap in graphene and function as a semiconducting switch. Although GNRs with widths of \textless 10 nm have been achieved, problems like GNR alignment, width control, uniformity, high aspect ratios, and edge roughness must be resolved in order to introduce GNRs as a robust alternative technology. Here we report patterning, characterization and superior chemical sensing of ultra-narrow aligned GNR arrays down to 5 nm width using helium ion beam lithography (HIBL) for the first time. The patterned GNR arrays possess narrow and adjustable widths, high aspect ratios, and relatively high quality. Field-effect transistors were fabricated on such GNR arrays and temperature-dependent transport measurements show the thermally activated carrier transport in the GNR array structure. Furthermore, we have demonstrated exceptional NO2 gas sensitivity of the 5 nm GNR array devices down to ppb levels. The results show the potential of HIBL fabricated GNRs for the electronic and sensing applications. [Preview Abstract] |
Wednesday, March 5, 2014 1:39PM - 1:51PM |
M30.00011: High Performance Chemical Sensing Using Schottky-Contacted CVD Grown Monolayer MoS2 Transistors Liang Chen, Bilu Liu, Chongwu Zhou Recently emerged two-dimensional (2D) crystals offer unique advantages as potential sensing materials with high sensitivity, owing to their very high surface-to-bulk atom ratios and semiconducting properties. Here, we report the first use of chemical vapor deposition grown monolayer MoS2 as high performance chemical sensors with Schottky contacts. The Schottky-contacted MoS2 transistors show current changes by two to three orders of magnitude upon exposure to NO2 and NH3. The MoS2 sensors show clear detection of NO2 down to 20 ppb and NH3 down to 1 ppm, both of which are the best among various monolayer or few-layer MoS2 and other 2D transition metal dichalcogenides materials based chemical sensors reported so far. We attribute the observed high performance to both well known charger transfer mechanism and more importantly, the Schottky barrier modulation upon analyte molecules adsorption, the latter of which is made possible by the Schottky contacts in our transistors and is not identified previously for MoS2 sensors. This study may open up new ways for 2D semiconductors as sensors and also may benefit the fundamental studies of interfacial phenomena and interactions between various chemical species and monolayer semiconductors. [Preview Abstract] |
Wednesday, March 5, 2014 1:51PM - 2:03PM |
M30.00012: Electrochemistry and molecular sensing in layered materials Nikita Repnin, Artem Baskin, Poya Yasaei, Reza Hantehzadeh, Bijandra Kumar, Petr Kral, Amin Salehi-Khojin We combine experimental and computational techniques to study electrochemistry in solvated MoS$_2$. We show that MoS$_2$ has a high catalytic activity for important industrial reactions. In a similar way, we investigate electronic transport properties of functionalized graphene with adsorbed molecules. We show that well designed nanostructures can lead to novel detection mechanisms with a very high molecular sensitivity. [Preview Abstract] |
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