Electron beam induced electronic transport in alkyl amine-intercalated VOx nanotubes

The electron beam induced electronic transport in primary alkyl amine-intercalated V2O5 nanotubes is investigated where the organic amine molecules are employed as molecular conductive wires to an aminosilanized substrate surface and contacted to Au interdigitated electrode contacts. The results demonstrate that the high conductivity of the nanotubes is related to the non-resonant tunnelling through the amine molecules and a reduced polaron hopping conduction through the vanadium oxide itself. Both nanotube networks and individual nanotubes exhibit similarly high conductivities where the minority carrier transport is bias dependent and nanotube diameter invariant

Semiquantitative theory of electronic Raman scattering from medium-size quantum dots

A consistent semiquantitative theoretical analysis of electronic Raman scattering from many-electron quantum dots under resonance excitation conditions has been performed. The theory is based on random-phase-approximation-like wave functions, with the Coulomb interactions treated exactly, and hole valence-band mixing accounted for within the Kohn-Luttinger Hamiltonian framework. The widths of intermediate and final states in the scattering process, although treated phenomenologically, play a significant role in the calculations, particularly for well above band gap excitation. The calculated polarized and unpolarized Raman spectra reveal a great complexity of features and details when the incident light energy is swept from below, through, and above the quantum dot band gap. Incoming and outgoing resonances dramatically modify the Raman intensities of the single particle, charge density, and spin density excitations. The theoretical results are presented in detail and discussed with regard to experimental observations.Comment: Submitted to Phys. Rev.

Nanocrystalline silicon optomechanical cavities

"© 2018 Optical Society of America. One print or electronic copy may be made for personal use only. Systematic reproduction and distribution, duplication of any material in this paper for a fee or for commercial purposes, or modifications of the content of this paper are prohibited"[EN] Silicon on insulator photonics has offered a versatile platform for the recent development of integrated optomechanical circuits. However, there are some constraints such as the high cost of the wafers and limitation to a single physical device level. In the present work we investigate nanocrystalline silicon as an alternative material for optomechanical devices. In particular we demonstrate that optomechanical crystal cavities fabricated of nanocrystalline silicon have optical and mechanical properties enabling non-linear dynamical behaviour and effects such as thermo-optic/free-carrier-dispersion self-pulsing, phonon lasing and chaos, all at low input laser power and with typical frequencies as high as 0.3 GHz. (C) 2018 Optical Society of America under the terms of the OSA Open Access Publishing AgreementEuropean Commission project PHENOMEN (H2020-EU-713450), MINECO Severo Ochoa Excellence program (SEV-2013-0295), MINECO (FIS2015-70862-P, RYC-2014-15392) and CERCA Programme/Generalitat de Catalunya.Navarro-Urrios, D.; Capuj, N.; Maire, J.; Colombano, M.; Jaramillo-Fernandez, J.; Chavez-Angel, E.; Martín-Rodríguez, LL.... (2018). Nanocrystalline silicon optomechanical cavities. Optics Express. 26(8):9829-9839. https://doi.org/10.1364/OE.26.009829S98299839268Kippenberg, T. J., & Vahala, K. J. (2008). Cavity Optomechanics: Back-Action at the Mesoscale. Science, 321(5893), 1172-1176. doi:10.1126/science.1156032Aspelmeyer, M., Kippenberg, T. J., & Marquardt, F. (2014). Cavity optomechanics. Reviews of Modern Physics, 86(4), 1391-1452. doi:10.1103/revmodphys.86.1391Navarro-Urrios, D., Capuj, N. E., Gomis-Bresco, J., Alzina, F., Pitanti, A., Griol, A., … Sotomayor Torres, C. M. (2015). A self-stabilized coherent phonon source driven by optical forces. Scientific Reports, 5(1). doi:10.1038/srep15733Navarro-Urrios, D., Capuj, N. E., Colombano, M. F., García, P. D., Sledzinska, M., Alzina, F., … Sotomayor-Torres, C. M. (2017). Nonlinear dynamics and chaos in an optomechanical beam. Nature Communications, 8(1). doi:10.1038/ncomms14965Leijssen, R., La Gala, G. R., Freisem, L., Muhonen, J. T., & Verhagen, E. (2017). Nonlinear cavity optomechanics with nanomechanical thermal fluctuations. Nature Communications, 8(1). doi:10.1038/ncomms16024Gil-Santos, E., Labousse, M., Baker, C., Goetschy, A., Hease, W., Gomez, C., … Favero, I. (2017). Light-Mediated Cascaded Locking of Multiple Nano-Optomechanical Oscillators. Physical Review Letters, 118(6). doi:10.1103/physrevlett.118.063605Shah, S. Y., Zhang, M., Rand, R., & Lipson, M. (2015). Master-Slave Locking of Optomechanical Oscillators over a Long Distance. Physical Review Letters, 114(11). doi:10.1103/physrevlett.114.113602Weis, S., Rivière, R., Deléglise, S., Gavartin, E., Arcizet, O., Schliesser, A., & Kippenberg, T. J. (2010). Optomechanically Induced Transparency. Science, 330(6010), 1520-1523. doi:10.1126/science.1195596Verhagen, E., Deléglise, S., Weis, S., Schliesser, A., & Kippenberg, T. J. (2012). Quantum-coherent coupling of a mechanical oscillator to an optical cavity mode. Nature, 482(7383), 63-67. doi:10.1038/nature10787Tomes, M., & Carmon, T. (2009). Photonic Micro-Electromechanical Systems Vibrating atX-band (11-GHz) Rates. Physical Review Letters, 102(11). doi:10.1103/physrevlett.102.113601Thompson, J. D., Zwickl, B. M., Jayich, A. M., Marquardt, F., Girvin, S. M., & Harris, J. G. E. (2008). Strong dispersive coupling of a high-finesse cavity to a micromechanical membrane. Nature, 452(7183), 72-75. doi:10.1038/nature06715Eichenfield, M., Chan, J., Camacho, R. M., Vahala, K. J., & Painter, O. (2009). Optomechanical crystals. Nature, 462(7269), 78-82. doi:10.1038/nature08524Chan, J., Alegre, T. P. M., Safavi-Naeini, A. H., Hill, J. T., Krause, A., Gröblacher, S., … Painter, O. (2011). Laser cooling of a nanomechanical oscillator into its quantum ground state. Nature, 478(7367), 89-92. doi:10.1038/nature10461Safavi-Naeini, A. H., Alegre, T. P. M., Chan, J., Eichenfield, M., Winger, M., Lin, Q., … Painter, O. (2011). Electromagnetically induced transparency and slow light with optomechanics. Nature, 472(7341), 69-73. doi:10.1038/nature09933Pennec, Y., Laude, V., Papanikolaou, N., Djafari-Rouhani, B., Oudich, M., El Jallal, S., … Martínez, A. (2014). Modeling light-sound interaction in nanoscale cavities and waveguides. Nanophotonics, 3(6), 413-440. doi:10.1515/nanoph-2014-0004Davanço, M., Ates, S., Liu, Y., & Srinivasan, K. (2014). Si3N4 optomechanical crystals in the resolved-sideband regime. Applied Physics Letters, 104(4), 041101. doi:10.1063/1.4858975Balram, K. C., Davanço, M. I., Song, J. D., & Srinivasan, K. (2016). Coherent coupling between radiofrequency, optical and acoustic waves in piezo-optomechanical circuits. Nature Photonics, 10(5), 346-352. doi:10.1038/nphoton.2016.46Bochmann, J., Vainsencher, A., Awschalom, D. D., & Cleland, A. N. (2013). Nanomechanical coupling between microwave and optical photons. Nature Physics, 9(11), 712-716. doi:10.1038/nphys2748Xiong, C., Pernice, W. H. P., Sun, X., Schuck, C., Fong, K. Y., & Tang, H. X. (2012). Aluminum nitride as a new material for chip-scale optomechanics and nonlinear optics. New Journal of Physics, 14(9), 095014. doi:10.1088/1367-2630/14/9/095014Gomis-Bresco, J., Navarro-Urrios, D., Oudich, M., El-Jallal, S., Griol, A., Puerto, D., … Torres, C. M. S. (2014). A one-dimensional optomechanical crystal with a complete phononic band gap. Nature Communications, 5(1). doi:10.1038/ncomms5452Heck, M. J. R., Bauters, J. F., Davenport, M. L., Spencer, D. T., & Bowers, J. E. (2014). Ultra-low loss waveguide platform and its integration with silicon photonics. Laser & Photonics Reviews, 8(5), 667-686. doi:10.1002/lpor.201300183Solehmainen, K., Aalto, T., Dekker, J., Kapulainen, M., Harjanne, M., Kukli, K., … Leskela, M. (2005). Dry-etched silicon-on-insulator waveguides with low propagation and fiber-coupling losses. Journal of Lightwave Technology, 23(11), 3875-3880. doi:10.1109/jlt.2005.857750Sekoguchi, H., Takahashi, Y., Asano, T., & Noda, S. (2014). Photonic crystal nanocavity with a Q-factor of ~9 million. Optics Express, 22(1), 916. doi:10.1364/oe.22.000916Almeida, V. R., Barrios, C. A., Panepucci, R. R., & Lipson, M. (2004). All-optical control of light on a silicon chip. Nature, 431(7012), 1081-1084. doi:10.1038/nature02921Narayanan, K., & Preble, S. F. (2010). Optical nonlinearities in hydrogenated-amorphous silicon waveguides. Optics Express, 18(9), 8998. doi:10.1364/oe.18.008998Preston, K., Dong, P., Schmidt, B., & Lipson, M. (2008). High-speed all-optical modulation using polycrystalline silicon microring resonators. Applied Physics Letters, 92(15), 151104. doi:10.1063/1.2908869Wang, K.-Y., & Foster, A. C. (2012). Ultralow power continuous-wave frequency conversion in hydrogenated amorphous silicon waveguides. Optics Letters, 37(8), 1331. doi:10.1364/ol.37.001331Matres, J., Ballesteros, G. C., Gautier, P., Fédéli, J.-M., Martí, J., & Oton, C. J. (2013). High nonlinear figure-of-merit amorphous silicon waveguides. Optics Express, 21(4), 3932. doi:10.1364/oe.21.003932Waldow, M., Plötzing, T., Gottheil, M., Först, M., Bolten, J., Wahlbrink, T., & Kurz, H. (2008). 25ps all-optical switching in oxygen implanted silicon-on-insulator microring resonator. Optics Express, 16(11), 7693. doi:10.1364/oe.16.007693Wang, K.-Y., Petrillo, K. G., Foster, M. A., & Foster, A. C. (2012). Ultralow-power all-optical processing of high-speed data signals in deposited silicon waveguides. Optics Express, 20(22), 24600. doi:10.1364/oe.20.024600Ylönen, M., Torkkeli, A., & Kattelus, H. (2003). In situ boron-doped LPCVD polysilicon with low tensile stress for MEMS applications. Sensors and Actuators A: Physical, 109(1-2), 79-87. doi:10.1016/j.sna.2003.09.017Theodorakos, I., Zergioti, I., Vamvakas, V., Tsoukalas, D., & Raptis, Y. S. (2014). Picosecond and nanosecond laser annealing and simulation of amorphous silicon thin films for solar cell applications. Journal of Applied Physics, 115(4), 043108. doi:10.1063/1.4863402Navarro-Urrios, D., Gomis-Bresco, J., El-Jallal, S., Oudich, M., Pitanti, A., Capuj, N., … Sotomayor Torres, C. M. (2014). Dynamical back-action at 5.5 GHz in a corrugated optomechanical beam. AIP Advances, 4(12), 124601. doi:10.1063/1.4902171Barclay, P. E., Srinivasan, K., & Painter, O. (2005). Nonlinear response of silicon photonic crystal micresonators excited via an integrated waveguide and fiber taper. Optics Express, 13(3), 801. doi:10.1364/opex.13.000801Cuffe, J., Ristow, O., Chávez, E., Shchepetov, A., Chapuis, P.-O., Alzina, F., … Sotomayor Torres, C. M. (2013). Lifetimes of Confined Acoustic Phonons in Ultrathin Silicon Membranes. Physical Review Letters, 110(9). doi:10.1103/physrevlett.110.095503Volklein, F., & Balles, H. (1992). A Microstructure For Measurement Of Thermal Conductivity Of Polysilicon Thin Films. 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Dynamical back-action at 5.5 GHz in a corrugated optomechanical beam

[EN] We report on the optomechanical properties of a breathing mechanical mode oscillating at 5.5 GHz in a 1D corrugated Si nanobeam. This mode has an experimental single-particle optomechanical coupling rate of vertical bar g(o, OM)vertical bar= 1.8 MHz (vertical bar g(o, OM)vertical bar/2 pi=0.3 MHz) and shows strong dynamical back-action effects at room temperature. The geometrical flexibility of the unit-cell would lend itself to further engineering of the cavity region to localize the mode within the full phononic band-gap present at 4 GHz while keeping high go, OM values. This would lead to longer lifetimes at cryogenic temperatures, due to the suppression of acoustic leakage.This work was supported by the EU through the FP7 project TAILPHOX (ICT-FP7-233883) and the ERC Advanced Grant SOULMAN (ERC-FP7-321122) and the Spanish projects TAPHOR (MAT2012-31392). D.N-U and J.G-B acknowledge support in the form of postdoctoral fellowships from the Catalan (Beatriu de Pinos) and the Spanish (Juan de la Cierva) governments, respectively.Navarro-Urrios, D.; Gomis-Bresco, J.; El-Jallal, S.; Oudich, M.; Pitanti, A.; Capuj, N.; Tredicucci, A.... (2014). Dynamical back-action at 5.5 GHz in a corrugated optomechanical beam. AIP Advances. 4(12). https://doi.org/10.1063/1.4902171S412Aspelmeyer, M., Kippenberg, T. J., & Marquardt, F. (Eds.). (2014). Cavity Optomechanics. doi:10.1007/978-3-642-55312-7Kippenberg, T. J., Rokhsari, H., Carmon, T., Scherer, A., & Vahala, K. J. (2005). Analysis of Radiation-Pressure Induced Mechanical Oscillation of an Optical Microcavity. Physical Review Letters, 95(3). doi:10.1103/physrevlett.95.033901Hossein-Zadeh, M., Rokhsari, H., Hajimiri, A., & Vahala, K. J. (2006). Characterization of a radiation-pressure-driven micromechanical oscillator. Physical Review A, 74(2). doi:10.1103/physreva.74.023813Eichenfield, M., Chan, J., Camacho, R. M., Vahala, K. J., & Painter, O. (2009). Optomechanical crystals. Nature, 462(7269), 78-82. doi:10.1038/nature08524Pennec, Y., Laude, V., Papanikolaou, N., Djafari-Rouhani, B., Oudich, M., El Jallal, S., … Martínez, A. (2014). Modeling light-sound interaction in nanoscale cavities and waveguides. Nanophotonics, 3(6). doi:10.1515/nanoph-2014-0004Chan, J., Alegre, T. P. M., Safavi-Naeini, A. H., Hill, J. T., Krause, A., Gröblacher, S., … Painter, O. (2011). Laser cooling of a nanomechanical oscillator into its quantum ground state. Nature, 478(7367), 89-92. doi:10.1038/nature10461Safavi-Naeini, A. H., Alegre, T. P. M., Chan, J., Eichenfield, M., Winger, M., Lin, Q., … Painter, O. (2011). Electromagnetically induced transparency and slow light with optomechanics. Nature, 472(7341), 69-73. doi:10.1038/nature09933Pennec, Y., Rouhani, B. D., Li, C., Escalante, J. M., Martinez, A., Benchabane, S., … Papanikolaou, N. (2011). Band gaps and cavity modes in dual phononic and photonic strip waveguides. AIP Advances, 1(4), 041901. doi:10.1063/1.3675799Gomis-Bresco, J., Navarro-Urrios, D., Oudich, M., El-Jallal, S., Griol, A., Puerto, D., … Torres, C. M. S. (2014). A one-dimensional optomechanical crystal with a complete phononic band gap. Nature Communications, 5(1). doi:10.1038/ncomms5452Oudich, M., El-Jallal, S., Pennec, Y., Djafari-Rouhani, B., Gomis-Bresco, J., Navarro-Urrios, D., … Makhoute, A. (2014). Optomechanic interaction in a corrugated phoxonic nanobeam cavity. Physical Review B, 89(24). doi:10.1103/physrevb.89.245122Chan, J., Safavi-Naeini, A. H., Hill, J. T., Meenehan, S., & Painter, O. (2012). Optimized optomechanical crystal cavity with acoustic radiation shield. Applied Physics Letters, 101(8), 081115. doi:10.1063/1.4747726Safavi-Naeini, A. H., Hill, J. T., Meenehan, S., Chan, J., Gröblacher, S., & Painter, O. (2014). Two-Dimensional Phononic-Photonic Band Gap Optomechanical Crystal Cavity. Physical Review Letters, 112(15). doi:10.1103/physrevlett.112.153603Johnson, S. G., Ibanescu, M., Skorobogatiy, M. A., Weisberg, O., Joannopoulos, J. D., & Fink, Y. (2002). Perturbation theory for Maxwell’s equations with shifting material boundaries. Physical Review E, 65(6). doi:10.1103/physreve.65.066611Navarro-Urrios, D., Gomis-Bresco, J., Capuj, N. E., Alzina, F., Griol, A., Puerto, D., … Sotomayor-Torres, C. M. (2014). Optical and mechanical mode tuning in an optomechanical crystal with light-induced thermal effects. Journal of Applied Physics, 116(9), 093506. doi:10.1063/1.4894623Barclay, P. E., Srinivasan, K., & Painter, O. (2005). Nonlinear response of silicon photonic crystal micresonators excited via an integrated waveguide and fiber taper. Optics Express, 13(3), 801. doi:10.1364/opex.13.000801J. Chan, Ph.D. thesis, California Institute of Technology, Los Angeles, 2014.Gorodetsky, M. L., Schliesser, A., Anetsberger, G., Deleglise, S., & Kippenberg, T. J. (2010). Determination of the vacuum optomechanical coupling rate using frequency noise calibration. Optics Express, 18(22), 23236. doi:10.1364/oe.18.02323

Low-temperature emission of Al0.48In0.52As under high pressures

We investigated the low‐temperature emission of Al0.48In0.52As under high pressures from 1 bar up to 92 kbar, paying special attention to the changes in luminescence mechanisms that occur concurrently with the crossover between the Γ‐ and the X‐related states. By investigating the temperature and excitation power dependence of the photoluminescence together with the photoluminescence excitation, we demonstrate the low‐temperature emission of Al0.48In0.52As is due to neutral donor‐acceptor‐pair (D 0,A 0) transitions with a relatively deep acceptor. This occurs in both the Γ‐ and the X‐related states. We suggest the shallow donor ground states associated with the X and the Γ conduction bands seem to be tied quite rigidly to these conduction bands. Variations in the donor binding energies with the pressure and the Γ‐X related state crossover seem to be minor. The linear pressure coefficients αΓ and α X of the (D 0,A 0) related to the Γ and the X levels in the conduction band are 7.9±0.1 and −2.9±0.1 meV/kbar, respectively. The Γ‐X related state crossover occurs at ∼52.5±0.5 kbar at 2 K. The direct band gapE Γ g and the indirect band gapE x g of Al0.48In0.52As are ∼1.61 and ∼2.17 eV at 1 bar and 2 K, respectively

Nuclear power in Argentina and Brazil

This article looks at nuclear power in Argentina and Brazi