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384 results on '"Steele, Gary"'

156. Single Photon Emission from Localized Excitons in Monolayer WSe2

Author

Tonndorf, Philipp, primary, Schmidt, Robert, additional, Kern, Johannes, additional, Buscema, Michele, additional, Steele, Gary, additional, Castellanos-Gomez, Andres, additional, van der Zant, Herre, additional, Michaelis de Vasconcellos, Steffen, additional, and Bratschitsch, Rudolf, additional

Published
2015
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164. Isolation and characterization of few-layer black phosphorus

Author

Castellanos-Gomez, Andres, primary, Vicarelli, Leonardo, additional, Prada, Elsa, additional, Island, Joshua O, additional, Narasimha-Acharya, K L, additional, Blanter, Sofya I, additional, Groenendijk, Dirk J, additional, Buscema, Michele, additional, Steele, Gary A, additional, Alvarez, J V, additional, Zandbergen, Henny W, additional, Palacios, J J, additional, and van der Zant, Herre S J, additional

Published
2014
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167. Ultrahigh Photoresponse of Few-Layer TiS3Nanoribbon Transistors

Author

Island, Joshua O., primary, Buscema, Michele, additional, Barawi, Mariam, additional, Clamagirand, José M., additional, Ares, José R., additional, Sánchez, Carlos, additional, Ferrer, Isabel J., additional, Steele, Gary A., additional, van der Zant, Herre S. J., additional, and Castellanos-Gomez, Andres, additional

Published
2014
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170. Local strain engineering in atomically thin MoS2

Author

Castellanos-Gómez, Andrés [0000-0002-3384-3405], Castellanos-Gómez, Andrés, Roldán, Rafael, Cappelluti, E., Buscema, M., Guinea, F., Zant, Herre S. J. van der, Steele, Gary A., Castellanos-Gómez, Andrés [0000-0002-3384-3405], Castellanos-Gómez, Andrés, Roldán, Rafael, Cappelluti, E., Buscema, M., Guinea, F., Zant, Herre S. J. van der, and Steele, Gary A.

Abstract

Controlling the bandstructure through local-strain engineering is an exciting avenue for tailoring optoelectronic properties of materials at the nanoscale. Atomically thin materials are particularly well-suited for this purpose because they can withstand extreme nonhomogeneous deformations before rupture. Here, we study the effect of large localized strain in the electronic bandstructure of atomically thin MoS2. Using photoluminescence imaging, we observe a strain-induced reduction of the direct bandgap and funneling of photogenerated excitons toward regions of higher strain. To understand these results, we develop a nonuniform tight-binding model to calculate the electronic properties of MoS2 nanolayers with complex and realistic local strain geometries, finding good agreement with our experimental results. © 2013 American Chemical Society.

Published
2013

171. A high quality factor carbon nanotube mechanical resonator at 39 GHz

Author

Laird, Edward A., Pei, Fei, Tang, Wei, Steele, Gary A., Kouwenhoven, Leo P., Laird, Edward A., Pei, Fei, Tang, Wei, Steele, Gary A., and Kouwenhoven, Leo P.

Abstract

We measure the mechanical resonances of an as-grown suspended carbon nanotube, detected via electrical mixing in the device. A sequence of modes extending to 39 GHz is observed with a quality factor of 35 000 in the highest mode. This unprecedentedly high combination corresponds to a thermal excited state probability below 10–8 and a relaxation time of 140 ns with microsecond relaxation times for lower modes. The effect of electron tunneling on the mechanical resonance is found to depend on frequency as the tunneling time becomes comparable to the vibration period.

Published
2012

172. Imaging transport resonances in the quantum Hall effect

Author

Raymond C. Ashoori., Massachusetts Institute of Technology. Dept. of Physics., Steele, Gary Alexander, Raymond C. Ashoori., Massachusetts Institute of Technology. Dept. of Physics., and Steele, Gary Alexander

Abstract

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Physics, 2006., MIT Institute Archives copy: p. 201-231 bound in reverse order., Includes bibliographical references (p. 213-231)., We image charge transport in the quantum Hall effect using a scanning charge accumulation microscope. Applying a DC bias voltage to the tip induces a highly resistive ring-shaped incompressible strip (IS) in a very high mobility 2D electron system (2DES). The IS moves with the tip as it is scanned, and acts as a barrier that prevents charging of the region under the tip. At certain tip positions, short-range disorder in the 2DES creates a quantum dot island inside the IS that enables breaching of the IS barrier by means of resonant tunneling through the island. Striking ring shapes appear in the images that directly reflect the shape of the IS created in the 2DES by the tip. Through the measurements of leakage across the IS, we extract information about energy gaps in the quantum Hall system. Varying the magnetic field, the tunneling resistance of the IS varies significantly, and takes on drastically different values at different filling factors. Measuring this tunneling resistance provides a unique microscopic probe of energy gaps in the quantum Hall system. Simulations of the interaction of the tip with the quantum Hall liquid show that native disorder from remote ionized donors can create the islands. The simulations predict the shape of the IS created in the 2DES in the presence of disorder, and comparison of the images with simulation results provides a direct and quantitative view of the disorder potential of a very high mobility 2DES. We also draw a connection to bulk transport. At quantum Hall plateaus, electrons in the bulk are localized by a network of ISs., We have observed that the conductance across one IS is drastically enhanced by resonant tunneling through quantum dot islands. Similarly, this resonant tunneling process will dramatically enhance the conductance of certain hopping paths in the localized bulk and could play an important role in dissipative transport at quantum Hall plateaus., by Gary Alexander Steele., Ph.D.

Published
2008

174. Local Strain Engineering in Atomically Thin MoS2

Author

Castellanos-Gomez, Andres, primary, Roldán, Rafael, additional, Cappelluti, Emmanuele, additional, Buscema, Michele, additional, Guinea, Francisco, additional, van der Zant, Herre S. J., additional, and Steele, Gary A., additional

Published
2013
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175. Single-Layer MoS2Mechanical Resonators

Author

Castellanos-Gomez, Andres, primary, van Leeuwen, Ronald, additional, Buscema, Michele, additional, van der Zant, Herre S. J., additional, Steele, Gary A., additional, and Venstra, Warner J., additional

Published
2013
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177. Fast and reliable identification of atomically thin layers of TaSe2 crystals

Author

Castellanos-Gomez, Andres, primary, Navarro-Moratalla, Efrén, additional, Mokry, Guillermo, additional, Quereda, Jorge, additional, Pinilla-Cienfuegos, Elena, additional, Agraït, Nicolás, additional, van der Zant, Herre S. J., additional, Coronado, Eugenio, additional, Steele, Gary A., additional, and Rubio-Bollinger, Gabino, additional

Published
2013
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198. Silicon nitride membrane resonators at millikelvin temperatures with quality factors exceeding 108.

Author

Mingyun Yuan, Cohen, Martijn A., and Steele, Gary A.

Subjects
SILICON nitride, ARTIFICIAL membranes, QUALITY factor, OPTOMECHANICS, TEMPERATURE effect
Abstract

We study the mechanical dissipation of the fundamental mode of millimeter-sized, high quality-factor (Q) metalized silicon nitride membranes at temperatures down to 14 mK using a three-dimensional optomechanical cavity. Below 200 mK, high-Q modes of the membranes show a diverging increase of Q with decreasing temperature, reaching Q = 1.27 × 108 at 14 mK, an order of magnitude higher than that reported before. The ultra-low dissipation makes the membranes highly attractive for the study of optomechanics in the quantum regime, as well as for other applications of optomechanics such as microwave to optical photon conversion. [ABSTRACT FROM AUTHOR]

Published
2015
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199. Observing the semiconducting band-gap alignment of MoS2 layers of different atomic thicknesses using a MoS2/SiO2/Si heterojunction tunnel diode.

Author

Nishiguchi, Katsuhiko, Castellanos-Gomez, Andres, Yamaguchi, Hiroshi, Fujiwara, Akira, van der Zant, Herre S. J., and Steele, Gary A.

Subjects
MOLYBDENUM compounds, BAND gaps, SEMICONDUCTORS, SILICA, THICKNESS measurement, HETEROJUNCTIONS, TUNNEL diodes
Abstract

We demonstrate a tunnel diode composed of a vertical MoS2/SiO2/Si heterostructure. A MoS2 flake consisting four areas of different thicknesses functions as a gate terminal of a silicon field-effect transistor. A thin gate oxide allows tunneling current to flow between the n-type MoS2 layers and p-type Si channel. The tunneling-current characteristics show multiple negative differential resistance features, which we interpret as an indication of different conduction-band alignments of the MoS2 layers of different thicknesses. The presented tunnel device can be also used as a hybrid-heterostructure device combining the advantages of two-dimensional materials with those of silicon transistors. [ABSTRACT FROM AUTHOR]

Published
2015
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200. Observing the semiconducting band-gap alignment of MoS2 layers of different atomic thicknesses using a MoS2/SiO2/Si heterojunction tunnel diode.

Author

Katsuhiko Nishiguchi, Castellanos-Gomez, Andres, Hiroshi Yamaguchi, Akira Fujiwara, van der Zant, Herre S. J., and Steele, Gary A.

Subjects
SEMICONDUCTOR devices, BAND gaps, FIELD-effect transistors, HETEROJUNCTIONS, N-type semiconductors, CONDUCTION bands, SILICON
Abstract

We demonstrate a tunnel diode composed of a vertical MoS2/SiO2/Si heterostructure. A MoS2 flake consisting four areas of different thicknesses functions as a gate terminal of a silicon field-effect transistor. A thin gate oxide allows tunneling current to flow between the n-type MoS2 layers and p-type Si channel. The tunneling-current characteristics show multiple negative differential resistance features, which we interpret as an indication of different conduction-band alignments of the MoS2 layers of different thicknesses. The presented tunnel device can be also used as a hybrid-heterostructure device combining the advantages of two-dimensional materials with those of silicon transistors. [ABSTRACT FROM AUTHOR]

Published
2015
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