Novel ultra-fast and nanoscale opto-electronic phenomena in 2d material heterostructures (Prof. F. Koppens)

  • Datum: 27.10.2015
  • Uhrzeit: 14:00 - 16:00
  • Vortragende(r): Prof. Dr. Frank Koppens, ICFO, The Institute of Photonic Sciences (Barcelona)
  • Raum: Herbert Walther Lecture Hall
  • Gastgeber: MPQ
The optoelectronic response of two-dimensional (2D) crystals, such as graphene and transition metal dichalcogenides (TMDs), is currently subject to intensive investigations. 

Owing to its broadband absorption, gapless character and ultrafast carrier dynamics, graphene is a promising material for nano-photonics and high-speed photodetectors [1], whereas TMDs have emerged as potential candidates for sensitive photodetection thanks to their enhanced photon absorption. Vertically assembling these crystals in so-called van der Waal heterostructures allows the creation of novel and versatile optoelectronic devices that combine the complementary properties of their constituent materials.Here we present a various new device capabilities, varying from nano-photonic devices to ultra-fast and broadband electrical detectors [1-5]. We applied femtosecond time-resolved photocurrent measurements on 2d material heterostructures, which probes the transit of photoexcited charges across the photoactive TMD layer – and thus current generation – directly in the time domain. In addition, nano-structured sandwiches of graphene with boron nitride have resulted in high quality plasmonic systems for infrared light. We discuss new configurations of these electrically tunable metamaterials and plasmonic circuits with in-situ tunable control of light at length scales more than a factor 150 below the free-space wavelength. We report strong improvements of the graphene plasmon lifetime and propagation lengths and we assess the intrinsic loss mechanisms [2,3]. Finally, we show how scanning near-field photocurrent microscopy is a promising new technique to gain insight into different device properties of standard graphene devices with a nanometre-scale resolution.

References:
[1] Photodetectors based on graphene, other two-dimensional materials and hybrid systems F. H. L. Koppens, T. Mueller, Ph. Avouris, A. C. Ferrari, M. S. Vitiello, M. Polini Nature Nanotechnol. 9, 780-793 (2014)
[2] Highly confined low-loss plasmons in graphene–boron nitride heterostructuresA. Woessner, M. B. Lundeberg, Y. Gao, A. Principi, P. Alonso-González, M. Carrega, K. Watanabe, T. Taniguchi,  G. Vignale, M. Polini, J. Hone, R. Hillenbrand, F. H. L. Koppens Nature Materials [online DOI: 10.1038/NMAT4169] (2014)
[3] Plasmon losses due to electron-phonon scattering: the case of graphene encapsulated in hexagonal Boron Nitride Alessandro Principi, Matteo Carrega, Mark Lundeberg, Achim Woessner, Frank H.L. Koppens, Giovanni Vignale, Marco Polini Phys. Rev. B 90, 165408 (2014)
[4] Electrical Control of Optical Emitter Relaxation Pathways enabled by Graphene K.J. Tielrooij, L. Orona, A. Ferrier, M. Badioli, G. Navickaite, S. Coop, S. Nanot, B. Kalinic, T. Cesca, L. Gaudreau, Q. Ma, A. Centeno, A. Pesquera, A. Zurutuza, H. de Riedmatten, P. Goldner, F.J. García de Abajo, P. Jarillo-Herrero, F.H.L. Koppens Nature Physics  [online DOI: 10.1038/nphys3204] (2015)
[5] Ultrafast electronic read-out of diamond NV centers coupled to graphene Andreas Brenneis, Louis Gaudreau, Max Seifert, Helmut Karl, Martin S. Brandt, Hans Huebl, Jose A. Garrido , Frank H.L. Koppens, Alexander W. Holleitner Nature Nanotechnology [online DOI: 10.1038/nnano.2014.276] (2014)

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