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1. Ultrafast Charge Transfer and Recombination Dynamics in Monolayer–Multilayer WSe2 Junctions Revealed by Time-Resolved Photoemission Electron Microscopy

Author

Xu, Ce, primary, Barden, Natalie, additional, Alexeev, Evgeny M., additional, Wang, Xiaoli, additional, Long, Run, additional, Cadore, Alisson R., additional, Paradisanos, Ioannis, additional, Ott, Anna K., additional, Soavi, Giancarlo, additional, Tongay, Sefaattin, additional, Cerullo, Giulio, additional, Ferrari, Andrea C., additional, Prezhdo, Oleg V., additional, and Loh, Zhi-Heng, additional

Published
2024
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4. Identification of Exciton Complexes in Charge-Tunable Janus WSeS Monolayers

Author

Feuer, Matthew S. G., primary, Montblanch, Alejandro R.-P., additional, Sayyad, Mohammed Y., additional, Purser, Carola M., additional, Qin, Ying, additional, Alexeev, Evgeny M., additional, Cadore, Alisson R., additional, Rosa, Barbara L. T., additional, Kerfoot, James, additional, Mostaani, Elaheh, additional, Kalȩba, Radosław, additional, Kolari, Pranvera, additional, Kopaczek, Jan, additional, Watanabe, Kenji, additional, Taniguchi, Takashi, additional, Ferrari, Andrea C., additional, Kara, Dhiren M., additional, Tongay, Sefaattin, additional, and Atatüre, Mete, additional

Published
2023
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6. Ultrafast Charge Transfer and Recombination Dynamics in Monolayer–Multilayer WSe2Junctions Revealed by Time-Resolved Photoemission Electron Microscopy

Author

Xu, Ce, Barden, Natalie, Alexeev, Evgeny M., Wang, Xiaoli, Long, Run, Cadore, Alisson R., Paradisanos, Ioannis, Ott, Anna K., Soavi, Giancarlo, Tongay, Sefaattin, Cerullo, Giulio, Ferrari, Andrea C., Prezhdo, Oleg V., and Loh, Zhi-Heng

Abstract

The ultrafast carrier dynamics of junctions between two chemically identical, but electronically distinct, transition metal dichalcogenides (TMDs) remains largely unknown. Here, we employ time-resolved photoemission electron microscopy (TR-PEEM) to probe the ultrafast carrier dynamics of a monolayer-to-multilayer (1L-ML) WSe2junction. The TR-PEEM signals recorded for the individual components of the junction reveal the sub-ps carrier cooling dynamics of 1L- and 7L-WSe2, as well as few-ps exciton–exciton annihilation occurring on 1L-WSe2. We observe ultrafast interfacial hole (h) transfer from 1L- to 7L-WSe2on an ∼0.2 ps time scale. The resultant excess h density in 7L-WSe2decays by carrier recombination across the junction interface on an ∼100 ps time scale. Reminiscent of the behavior at a depletion region, the TR-PEEM image reveals the h density accumulation on the 7L-WSe2interface, with a decay length ∼0.60 ± 0.17 μm. These charge transfer and recombination dynamics are in agreement with ab initioquantum dynamics. The computed orbital densities reveal that charge transfer occurs from the basal plane, which extends over both 1L and ML regions, to the upper plane localized on the ML region. This mode of charge transfer is distinctive to chemically homogeneous junctions of layered materials and constitutes an additional carrier deactivation pathway that should be considered in studies of 1L-TMDs found alongside their ML, a common occurrence in exfoliated samples.

Published
2024
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9. Ultrafast Electronic Relaxation Dynamics of Atomically Thin MoS2Is Accelerated by Wrinkling

Author

Xu, Ce, Zhou, Guoqing, Alexeev, Evgeny M., Cadore, Alisson R., Paradisanos, Ioannis, Ott, Anna K., Soavi, Giancarlo, Tongay, Sefaattin, Cerullo, Giulio, Ferrari, Andrea C., Prezhdo, Oleg V., and Loh, Zhi-Heng

Abstract

Strain engineering is an attractive approach for tuning the local optoelectronic properties of transition metal dichalcogenides (TMDs). While strain has been shown to affect the nanosecond carrier recombination dynamics of TMDs, its influence on the sub-picosecond electronic relaxation dynamics is still unexplored. Here, we employ a combination of time-resolved photoemission electron microscopy (TR-PEEM) and nonadiabatic ab initiomolecular dynamics (NAMD) to investigate the ultrafast dynamics of wrinkled multilayer (ML) MoS2comprising 17 layers. Following 2.41 eV photoexcitation, electronic relaxation at the Γ valley occurs with a time constant of 97 ± 2 fs for wrinkled ML-MoS2and 120 ± 2 fs for flat ML-MoS2. NAMD shows that wrinkling permits larger amplitude motions of MoS2layers, relaxes electron–phonon coupling selection rules, perturbs chemical bonding, and increases the electronic density of states. As a result, the nonadiabatic coupling grows and electronic relaxation becomes faster compared to flat ML-MoS2. Our study suggests that the sub-picosecond electronic relaxation dynamics of TMDs is amenable to strain engineering and that applications which require long-lived hot carriers, such as hot-electron-driven light harvesting and photocatalysis, should employ wrinkle-free TMDs.

Published
2023
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10. Identification of Exciton Complexes in Charge-Tunable Janus WSeS Monolayers.

Author

Feuer, Matthew S. G., Montblanch, Alejandro R.-P., Sayyad, Mohammed Y., Purser, Carola M., Qin, Ying, Alexeev, Evgeny M., Cadore, Alisson R., Rosa, Barbara L. T., Kerfoot, James, Mostaani, Elaheh, Kalȩba, Radosław, Kolari, Pranvera, Kopaczek, Jan, Watanabe, Kenji, Taniguchi, Takashi, Ferrari, Andrea C., Kara, Dhiren M., Tongay, Sefaattin, and Atatüre, Mete

Published
2023
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12. Electrically Tunable Nonequilibrium Optical Response of Graphene

Author

Pogna, Eva A. A., primary, Tomadin, Andrea, additional, Balci, Osman, additional, Soavi, Giancarlo, additional, Paradisanos, Ioannis, additional, Guizzardi, Michele, additional, Pedrinazzi, Paolo, additional, Mignuzzi, Sandro, additional, Tielrooij, Klaas-Jan, additional, Polini, Marco, additional, Ferrari, Andrea C., additional, and Cerullo, Giulio, additional

Published
2022
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15. Wafer-Scale Integration of Graphene-Based Photonic Devices

Author

Giambra, Marco A., primary, Mišeikis, Vaidotas, additional, Pezzini, Sergio, additional, Marconi, Simone, additional, Montanaro, Alberto, additional, Fabbri, Filippo, additional, Sorianello, Vito, additional, Ferrari, Andrea C., additional, Coletti, Camilla, additional, and Romagnoli, Marco, additional

Published
2021
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16. Weak Distance Dependence of Hot-Electron-Transfer Rates at the Interface between Monolayer MoS2 and Gold

Author

Xu, Ce, primary, Yong, Hui Wen, additional, He, Jinlu, additional, Long, Run, additional, Cadore, Alisson R., additional, Paradisanos, Ioannis, additional, Ott, Anna K., additional, Soavi, Giancarlo, additional, Tongay, Sefaattin, additional, Cerullo, Giulio, additional, Ferrari, Andrea C., additional, Prezhdo, Oleg V., additional, and Loh, Zhi-Heng, additional

Published
2020
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17. Ultrafast, Zero-Bias, Graphene Photodetectors with Polymeric Gate Dielectric on Passive Photonic Waveguides

Author

Mišeikis, Vaidotas, primary, Marconi, Simone, additional, Giambra, Marco A., additional, Montanaro, Alberto, additional, Martini, Leonardo, additional, Fabbri, Filippo, additional, Pezzini, Sergio, additional, Piccinini, Giulia, additional, Forti, Stiven, additional, Terrés, Bernat, additional, Goykhman, Ilya, additional, Hamidouche, Louiza, additional, Legagneux, Pierre, additional, Sorianello, Vito, additional, Ferrari, Andrea C., additional, Koppens, Frank H. L., additional, Romagnoli, Marco, additional, and Coletti, Camilla, additional

Published
2020
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18. Strongly Coupled Coherent Phonons in Single-Layer MoS2

Author

Trovatello, Chiara, primary, Miranda, Henrique P. C., additional, Molina-Sánchez, Alejandro, additional, Borrego-Varillas, Rocío, additional, Manzoni, Cristian, additional, Moretti, Luca, additional, Ganzer, Lucia, additional, Maiuri, Margherita, additional, Wang, Junjia, additional, Dumcenco, Dumitru, additional, Kis, Andras, additional, Wirtz, Ludger, additional, Marini, Andrea, additional, Soavi, Giancarlo, additional, Ferrari, Andrea C., additional, Cerullo, Giulio, additional, Sangalli, Davide, additional, and Conte, Stefano Dal, additional

Published
2020
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19. High-Mobility, Wet-Transferred Graphene Grown by Chemical Vapor Deposition

Author

De Fazio, Domenico, primary, Purdie, David G., additional, Ott, Anna K., additional, Braeuninger-Weimer, Philipp, additional, Khodkov, Timofiy, additional, Goossens, Stijn, additional, Taniguchi, Takashi, additional, Watanabe, Kenji, additional, Livreri, Patrizia, additional, Koppens, Frank H. L., additional, Hofmann, Stephan, additional, Goykhman, Ilya, additional, Ferrari, Andrea C., additional, and Lombardo, Antonio, additional

Published
2019
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21. Weak Distance Dependence of Hot-Electron-Transfer Rates at the Interface between Monolayer MoS2and Gold

Author

Xu, Ce, Yong, Hui Wen, He, Jinlu, Long, Run, Cadore, Alisson R., Paradisanos, Ioannis, Ott, Anna K., Soavi, Giancarlo, Tongay, Sefaattin, Cerullo, Giulio, Ferrari, Andrea C., Prezhdo, Oleg V., and Loh, Zhi-Heng

Abstract

Electron transport across the transition-metal dichalcogenide (TMD)/metal interface plays an important role in determining the performance of TMD-based optoelectronic devices. However, the robustness of this process against structural heterogeneities remains unexplored, to the best of our knowledge. Here, we employ a combination of time-resolved photoemission electron microscopy (TR-PEEM) and atomic force microscopy to investigate the spatially resolved hot-electron-transfer dynamics at the monolayer (1L) MoS2/Au interface. A spatially heterogeneous distribution of 1L-MoS2/Au gap distances, along with the sub-80 nm spatial- and sub-60 fs temporal resolution of TR-PEEM, permits the simultaneous measurement of electron-transfer rates across a range of 1L-MoS2/Au distances. These decay exponentially as a function of distance, with an attenuation coefficient β ∼ 0.06 ± 0.01 Å–1, comparable to molecular wires. Ab initiosimulations suggest that surface plasmon-like states mediate hot-electron-transfer, hence accounting for its weak distance dependence. The weak distance dependence of the interfacial hot-electron-transfer rate indicates that this process is insensitive to distance fluctuations at the TMD/metal interface, thus motivating further exploration of optoelectronic devices based on hot carriers.

Published
2021
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23. Microfluidization of Graphite and Formulation of Graphene-Based Conductive Inks

Author

Karagiannidis, Panagiotis G., primary, Hodge, Stephen A., additional, Lombardi, Lucia, additional, Tomarchio, Flavia, additional, Decorde, Nicolas, additional, Milana, Silvia, additional, Goykhman, Ilya, additional, Su, Yang, additional, Mesite, Steven V., additional, Johnstone, Duncan N., additional, Leary, Rowan K., additional, Midgley, Paul A., additional, Pugno, Nicola M., additional, Torrisi, Felice, additional, and Ferrari, Andrea C., additional

Published
2017
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24. Graphene Phase Modulators Operating in the Transparency Regime

Author

Watson, Hannah F. Y., Ruocco, Alfonso, Tiberi, Matteo, Muench, Jakob E., Balci, Osman, Shinde, Sachin M., Mignuzzi, Sandro, Pantouvaki, Marianna, Van Thourhout, Dries, Sordan, Roman, Tomadin, Andrea, Sorianello, Vito, Romagnoli, Marco, and Ferrari, Andrea C.

Abstract

Next-generation data networks need to support Tb/s rates. In-phase and quadrature (IQ) modulation combine phase and intensity information to increase the density of encoded data, reduce overall power consumption by minimizing the number of channels, and increase noise tolerance. To reduce errors when decoding the received signal, intersymbol interference must be minimized. This is achieved with pure phase modulation, where the phase of the optical signal is controlled without changing its intensity. Phase modulators are characterized by the voltage required to achieve a π phase shift, Vπ, the device length, L, and their product, VπL. To reduce power consumption, IQ modulators are needed with <1 V drive voltages and compact (sub-cm) dimensions, which translate in VπL< 1Vcm. Si and LiNbO3(LN) IQ modulators do not currently meet these requirements because VπL> 1Vcm. Here, we report a double single-layer graphene (SLG) Mach–Zehnder modulator (MZM) with pure phase modulation in the transparency regime, where optical losses are minimized and remain constant with increasing voltage. Our device has VπL∼ 0.3Vcm, matching state-of-the-art SLG-based MZMs and plasmonic LN MZMs, but with pure phase modulation and low insertion loss (∼5 dB), essential for IQ modulation. Our VπLis ∼5 times lower than the lowest thin-film LN MZMs and ∼3 times lower than the lowest Si MZMs. This enables devices with complementary metal-oxide semiconductor compatible VπL(<1Vcm) and smaller footprint than LN or Si MZMs, improving circuit density and reducing power consumption by 1 order of magnitude.

Published
2024
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25. Double-Wall Carbon Nanotubes for Wide-Band, Ultrafast Pulse Generation

Author

Hasan, Tawfique, Sun, Zhipei, Tan, PingHeng, Popa, Daniel, Flahaut, Emmanuel, Kelleher, Edmund J. R., Bonaccorso, Francesco, Wang, Fengqiu, Jiang, Zhe, Torrisi, Felice, Privitera, Giulia, Nicolosi, Valeria, Ferrari, Andrea C., Centre National de la Recherche Scientifique - CNRS (FRANCE), Chinese Academy of Sciences (CHINA), Institut National Polytechnique de Toulouse - INPT (FRANCE), University of Cambridge (UNITED KINGDOM), Université Toulouse III - Paul Sabatier - UPS (FRANCE), Aalto University (FINLAND), Advanced Materials and BioEngineering Research - AMBER (IRELAND), Imperial College London (UNITED KINGDOM), Istituto per i Processi Chimico-Fisici - IPCF (ITALY), Nanjing University - NJU (CHINA), Cambridge Graphene Centre (Cambridge, United Kingdom), State Key Laboratory for Superlattices and Microstructures (Beijing, China), Centre Interuniversitaire de Recherche et d'Ingénierie des Matériaux - CIRIMAT (Toulouse, France), Femtosecond Optics Group - FOG (London, United Kingdom), Université Toulouse III - Paul Sabatier - UT3 (FRANCE), Institut National Polytechnique de Toulouse - Toulouse INP (FRANCE), Cambridge Graphene Centre (Cambridge, UK), Aalto University, State Key Laboratory for Superlattices and Microstructures Institute of Semiconductors, Chinese Academy of Sciences, State Key Laboratory, Centre interuniversitaire de recherche et d'ingenierie des matériaux (CIRIMAT), Centre National de la Recherche Scientifique (CNRS)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut National Polytechnique (Toulouse) (Toulouse INP), Université Fédérale Toulouse Midi-Pyrénées-Institut de Chimie du CNRS (INC), Femtosecond Optics Group (FOG), Department of Physics [Imperial College London], Imperial College London-Imperial College London, CNR Istituto per i Processi Chimico-Fisici (IPCF), Consiglio Nazionale delle Ricerche [Messina] (CNR), and Nanjing University (NJU)

Subjects
GRAPHENE, Technology, CHEMISTRY, PHYSICAL, NANOSCIENCE & NANOTECHNOLOGY, Chemistry, Multidisciplinary, Matériaux, Materials Science, MU-M, MATERIALS SCIENCE, MULTIDISCIPLINARY, Ultrafast laser, MODE-LOCKING, [SPI.MAT]Engineering Sciences [physics]/Materials, SINGLE-WALL, RAMAN-SPECTROSCOPY, Saturable absorber, MD Multidisciplinary, Double-wall carbon nanotubes, Polymer composites, Science & Technology, NONLINEAR-OPTICAL RESPONSE, [CHIM.MATE]Chemical Sciences/Material chemistry, Chemistry, FIBER LASERS, Physical Sciences, Science & Technology - Other Topics, ENERGY-TRANSFER
Abstract

International audience; We demonstrate wide-band ultrafast optical pulse generation at 1, 1.5, and 2 μm using a single-polymer composite saturable absorber based on double-wall carbon nanotubes (DWNTs). The freestanding optical quality polymer composite is prepared from nanotubes dispersed in water with poly(vinyl alcohol) as the host matrix. The composite is then integrated into ytterbium-, erbium-, and thulium-doped fiber laser cavities. Using this single DWNT–polymer composite, we achieve 4.85 ps, 532 fs, and 1.6 ps mode-locked pulses at 1066, 1559, and 1883 nm, respectively, highlighting the potential of DWNTs for wide-band ultrafast photonics.

Published
2014

26. High Responsivity, Large-Area Graphene/MoS2 Flexible Photodetectors

Author

De Fazio, Domenico, primary, Goykhman, Ilya, additional, Yoon, Duhee, additional, Bruna, Matteo, additional, Eiden, Anna, additional, Milana, Silvia, additional, Sassi, Ugo, additional, Barbone, Matteo, additional, Dumcenco, Dumitru, additional, Marinov, Kolyo, additional, Kis, Andras, additional, and Ferrari, Andrea C., additional

Published
2016
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27. Graphene-Based Interfaces Do Not Alter Target Nerve Cells

Author

Fabbro, Alessandra, primary, Scaini, Denis, additional, León, Verónica, additional, Vázquez, Ester, additional, Cellot, Giada, additional, Privitera, Giulia, additional, Lombardi, Lucia, additional, Torrisi, Felice, additional, Tomarchio, Flavia, additional, Bonaccorso, Francesco, additional, Bosi, Susanna, additional, Ferrari, Andrea C., additional, Ballerini, Laura, additional, and Prato, Maurizio, additional

Published
2016
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28. Photo-Induced Bandgap Renormalization Governs the Ultrafast Response of Single-Layer MoS2

Author

Pogna, Eva A. A., primary, Marsili, Margherita, additional, De Fazio, Domenico, additional, Dal Conte, Stefano, additional, Manzoni, Cristian, additional, Sangalli, Davide, additional, Yoon, Duhee, additional, Lombardo, Antonio, additional, Ferrari, Andrea C., additional, Marini, Andrea, additional, Cerullo, Giulio, additional, and Prezzi, Deborah, additional

Published
2016
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29. Raman Radiation Patterns of Graphene

Author

Budde, Harald, primary, Coca-López, Nicolás, additional, Shi, Xian, additional, Ciesielski, Richard, additional, Lombardo, Antonio, additional, Yoon, Duhee, additional, Ferrari, Andrea C., additional, and Hartschuh, Achim, additional

Published
2015
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32. Nanotubes Complexed with DNA and Proteins for Resistive-Pulse Sensing

Author

Sha, Jingjie, primary, Hasan, Tawfique, additional, Milana, Silvia, additional, Bertulli, Cristina, additional, Bell, Nicholas A. W., additional, Privitera, Giulia, additional, Ni, Zhonghua, additional, Chen, Yunfei, additional, Bonaccorso, Francesco, additional, Ferrari, Andrea C., additional, Keyser, Ulrich F., additional, and Huang, Yan Yan S., additional

Published
2013
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35. Inkjet-Printed Graphene Electronics

Author

Torrisi, Felice, primary, Hasan, Tawfique, additional, Wu, Weiping, additional, Sun, Zhipei, additional, Lombardo, Antonio, additional, Kulmala, Tero S., additional, Hsieh, Gen-Wen, additional, Jung, Sungjune, additional, Bonaccorso, Francesco, additional, Paul, Philip J., additional, Chu, Daping, additional, and Ferrari, Andrea C., additional

Published
2012
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38. Brownian Motion of Graphene

Author

Maragó, Onofrio M., primary, Bonaccorso, Francesco, additional, Saija, Rosalba, additional, Privitera, Giulia, additional, Gucciardi, Pietro G., additional, Iatì, Maria Antonia, additional, Calogero, Giuseppe, additional, Jones, Philip H., additional, Borghese, Ferdinando, additional, Denti, Paolo, additional, Nicolosi, Valeria, additional, and Ferrari, Andrea C., additional

Published
2010
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41. Surface-Enhanced Raman Spectroscopy of Graphene

Author

Schedin, Fred, primary, Lidorikis, Elefterios, additional, Lombardo, Antonio, additional, Kravets, Vasyl G., additional, Geim, Andre K., additional, Grigorenko, Alexander N., additional, Novoselov, Kostya S., additional, and Ferrari, Andrea C., additional

Published
2010
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42. Graphene Mode-Locked Ultrafast Laser

Author

Sun, Zhipei, primary, Hasan, Tawfique, additional, Torrisi, Felice, additional, Popa, Daniel, additional, Privitera, Giulia, additional, Wang, Fengqiu, additional, Bonaccorso, Francesco, additional, Basko, Denis M., additional, and Ferrari, Andrea C., additional

Published
2010
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46. High Responsivity, Large-Area Graphene/MoS2Flexible Photodetectors

Author

De Fazio, Domenico, Goykhman, Ilya, Yoon, Duhee, Bruna, Matteo, Eiden, Anna, Milana, Silvia, Sassi, Ugo, Barbone, Matteo, Dumcenco, Dumitru, Marinov, Kolyo, Kis, Andras, and Ferrari, Andrea C.

Abstract

We present flexible photodetectors (PDs) for visible wavelengths fabricated by stacking centimeter-scale chemical vapor deposited (CVD) single layer graphene (SLG) and single layer CVD MoS2, both wet transferred onto a flexible polyethylene terephthalate substrate. The operation mechanism relies on injection of photoexcited electrons from MoS2to the SLG channel. The external responsivity is 45.5A/W and the internal 570A/W at 642 nm. This is at least 2 orders of magnitude higher than bulk-semiconductor flexible membranes. The photoconductive gain is up to 4 × 105. The photocurrent is in the 0.1–100 μA range. The devices are semitransparent, with 8% absorptance at 642 nm, and are stable upon bending to a curvature of 1.4 cm. These capabilities and the low-voltage operation (<1 V) make them attractive for wearable applications.

Published
2016
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47. Raman Radiation Patterns of Graphene

Author

Budde, Harald, Coca-López, Nicolás, Shi, Xian, Ciesielski, Richard, Lombardo, Antonio, Yoon, Duhee, Ferrari, Andrea C., and Hartschuh, Achim

Abstract

We report the angular distribution of the G and 2D Raman scattering from graphene on glass by detecting back focal plane patterns. The G Raman emission can be described by a superposition of two incoherent orthogonal point dipoles oriented in the graphene plane. Due to double resonant Raman scattering, the 2D emission can be represented by the sum of either three incoherent dipoles oriented 120° with respect to each other, or two orthogonal incoherent ones with a 3:1 weight ratio. Parameter-free calculations of the G and 2D intensities are in excellent agreement with the experimental radiation patterns. We show that the 2D polarization ratio and the 2D/G intensity ratio depend on the numerical aperture of the microscope objective. This is due to the depolarization of the emission and excitation light when graphene is on a dielectric substrate, as well as to tight focusing. The polarization contrast decreases substantially for increasing collection angle, due to polarization mixing caused by the air-dielectric interface. This also influences the intensity ratio I(2D)/I(G), a crucial quantity for estimating the doping in graphene. Our results are thus important for the quantitative analysis of the Raman intensities in confocal microscopy. In addition, they are relevant for understanding the influence of signal enhancing plasmonic antenna structures, which typically modify the sample’s radiation pattern.

Published
2016
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48. Synthesis of YBa2Cu3O7−δand Y2BaCuO5Nanocrystalline Powders for YBCO Superconductors Using Carbon Nanotube Templates

Author

Shi, Yunhua, Hasan, Tawfique, Babu, Nadendla H., Torrisi, Felice, Milana, Silvia, Ferrari, Andrea C., and Cardwell, David A.

Abstract

We fabricate nanosized superconducting YBa2Cu3O7−δ(Y-123) and nonsuperconducting Y2BaCuO5(Y-211) powders using carbon nanotubes as template. The mean particle size of Y-123 and Y-211 is 12 and 30 nm, respectively. The superconducting transition temperature of the Y-123 nanopowder is 90.9 K, similar to that of commercial, micrometer-scale powders fabricated by conventional processing. The elimination of carbon and the formation of a high purity superconducting phase both on the micro- and macroscale is confirmed by Raman spectroscopy and X-ray diffraction. We also demonstrate improvement in the superconducting properties of YBCO single grain bulk samples fabricated using the nanosize Y-211 powder, both in terms of trapped field and critical current density. The former reaches 553 mT at 77 K, with a ∼20% improvement compared to samples fabricated from commercial powders. Thus, our processing method is an effective source of pinning centers in single grain superconductors.

Published
2012
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49. Chip-Scalable, Room-Temperature, Zero-Bias, Graphene-Based Terahertz Detectors with Nanosecond Response Time

Author

Elisa Riccardi, Leonardo Viti, Domenico De Fazio, Sandro Mignuzzi, Osman Balci, Jincan Zhang, Miriam S. Vitiello, Andrea C. Ferrari, Mahdi Asgari, Frank H. L. Koppens, Sachin M. Shinde, Balci, Osman [0000-0003-2766-2197], Zhang, Jincan [0000-0002-7131-4491], Koppens, Frank HL [0000-0001-9764-6120], Ferrari, Andrea [0000-0003-0907-9993], Viti, Leonardo [0000-0002-4844-2081], Vitiello, Miriam S [0000-0002-4914-0421], and Apollo - University of Cambridge Repository

Subjects
Materials science, Orders of magnitude (temperature), Terahertz radiation, Nanophotonics, General Physics and Astronomy, Photodetector, 02 engineering and technology, 7. Clean energy, 01 natural sciences, Noise (electronics), Article, chemical vapor deposition, law.invention, terahertz, graphene, nanophotonics, photodetectors, law, 0103 physical sciences, General Materials Science, 010306 general physics, business.industry, Graphene, Settore FIS/01 - Fisica Sperimentale, General Engineering, Microbolometer, 021001 nanoscience & nanotechnology, Optoelectronics, Photonics, 0210 nano-technology, business
Abstract

The scalable synthesis and transfer of large-area graphene underpins the development of nanoscale photonic devices ideal for new applications in a variety of fields, ranging from biotechnology, to wearable sensors for healthcare and motion detection, to quantum transport, communications, and metrology. We report room-temperature zero-bias thermoelectric photodetectors, based on single- and polycrystal graphene grown by chemical vapor deposition (CVD), tunable over the whole terahertz range (0.1-10 THz) by selecting the resonance of an on-chip patterned nanoantenna. Efficient light detection with noise equivalent powers

Published
2021

50. Moiré Modulation of Van Der Waals Potential in Twisted Hexagonal Boron Nitride

Author

Stefano Chiodini, James Kerfoot, Giacomo Venturi, Sandro Mignuzzi, Evgeny M. Alexeev, Bárbara Teixeira Rosa, Sefaattin Tongay, Takashi Taniguchi, Kenji Watanabe, Andrea C. Ferrari, Antonio Ambrosio, Kerfoot, James [0000-0002-6041-4833], Alexeev, Evgeny M [0000-0002-8149-6364], Tongay, Sefaattin [0000-0001-8294-984X], Taniguchi, Takashi [0000-0002-1467-3105], Watanabe, Kenji [0000-0003-3701-8119], Ferrari, Andrea C [0000-0003-0907-9993], Ambrosio, Antonio [0000-0002-8519-3862], and Apollo - University of Cambridge Repository

Subjects
atomic force microscopy, layered materials, moiré superlattices, General Engineering, Physics::Atomic and Molecular Clusters, General Physics and Astronomy, General Materials Science, hexagonal boron nitride, mechanical phase imaging, van der Waals interactions
Abstract

Funder: European Commission, When a twist angle is applied between two layered materials (LMs), the registry of the layers and the associated change in their functional properties are spatially modulated, and a moiré superlattice arises. Several works explored the optical, electric, and electromechanical moiré-dependent properties of such twisted LMs but, to the best of our knowledge, no direct visualization and quantification of van der Waals (vdW) interlayer interactions has been presented, so far. Here, we use tapping mode atomic force microscopy phase-imaging to probe the spatial modulation of the vdW potential in twisted hexagonal boron nitride. We find a moiré superlattice in the phase channel only when noncontact (long-range) forces are probed, revealing the modulation of the vdW potential at the sample surface, following AB and BA stacking domains. The creation of scalable electrostatic domains, modulating the vdW potential at the interface with the environment by means of layer twisting, could be used for local adhesion engineering and surface functionalization by affecting the deposition of molecules or nanoparticles.

Published
2022
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