Search results for " Tunnel"
showing 10 items of 477 documents
Addressing and imaging high optical index dielectric ridges in the optical near field
2001
Experimental observation of light coupling between ${\mathrm{TiO}}_{2}$ integrated waveguides of subwavelength cross section and pure three-dimensional evanescent light fields is reported. This near-field optical phenomenon is produced by controlling the location of the focusing of a laser beam totally reflected at the surface of the sample. The phenomenon is observed in direct space with a photon scanning tunneling microscope. Dielectric ridges several tens of micrometers long have been efficiently excited with this technique. Upon excitation, the extremities of the linear dielectric wires display intense light spots localized both inside and around the ridge. For ridge lengths up to $30\e…
Temperature and bias-voltage dependence of atomic-layer-deposited HfO2-based magnetic tunnel junctions
2014
Magnetic tunnel junctions with HfO2 tunnel barriers were prepared through a combination of magnetron sputtering and atomic layer deposition. We investigated the tunneling transport behavior, including the tunnel magnetoresistance ratio and the current-voltage characteristics between room temperature and 2 K. Here, we achieved a tunneling magneto resistance ratio of 10.3% at room temperature and 19.3% at 2 K. Furthermore, we studied the bias-voltage and temperature dependencies and compared the results with those of commonly used alumina- and magnesia-based magnetic tunnel junctions. We observed a polycrystalline/amorphous electrode-barrier system via high-resolution transmission electron mi…
Superconducting tantalum nitride-based normal metal-insulator-superconductor tunnel junctions
2014
We report the development of superconducting tantalum nitride (TaN$_{x} $) normal metal-insulator-superconductor (NIS) tunnel junctions. For the insulating barrier, we used both AlO$_{x}$ and TaO$_{x}$ (Cu-AlO$_{x}$-Al-TaN$_{x} $ and Cu-TaO$_{x}$-TaN$_{x} $), with both devices exhibiting temperature dependent current-voltage characteristics which follow the simple one-particle tunneling model. The superconducting gap follows a BCS type temperature dependence, rendering these devices suitable for sensitive thermometry and bolometry from the superconducting transition temperature $T_{\text{C}}$ of the TaN$_{x} $ film at $\sim 5$ K down to $\sim$ 0.5 K. Numerical simulations were also performe…
Dopant-controlled single-electron pumping through a metallic island
2016
We investigate a hybrid metallic island/single dopant electron pump based on fully depleted silicon-on-insulator technology. Electron transfer between the central metallic island and the leads is controlled by resonant tunneling through single phosphorus dopants in the barriers. Top gates above the barriers are used to control the resonance conditions. Applying radio frequency signals to the gates, non-adiabatic quantized electron pumping is achieved. A simple deterministic model is presented and confirmed by comparing measurements with simulations.
Characterization of soft breakdown in thin oxide NMOSFETs based on the analysis of the substrate current
2001
We have investigated the properties of soft breakdown (SBO) in thin oxide (4.5 nm) nMOSFETs with measurements of the gate and substrate leakage currents using the carrier separation technique. We have observed that, at lower gate voltages, the level of the substrate current exhibits a plateau. We propose that the observed plateau is due to the Shockley-Hall-Read (SHR) generation of hole-electron pairs in the space charge region and at the Si-SiO/sub 2/ interface. At higher voltages, the substrate current steeply increases with voltage, due to a tunneling mechanism, trap-assisted or due to a localized effective thinning of the oxide, from the substrate valence band to the gate conduction ban…
Energy scales and dynamics of electronic excitations in functionalized gold nanoparticles measured at the single particle level.
2019
The knowledge of the electronic structure and dynamics of nanoparticles is a prerequisite to develop miniaturized single-electron devices based on nanoparticles. Low-temperature transport measurements of individual stable metallic nanoparticles enable unravelling the system specific electronic structure while ultrafast optical spectroscopy gives access to the electron dynamics. In this work, we investigate bare and thiol-functionalized gold nanoparticles. For the latter, we employ a fast and low-cost fabrication technique which yields nanoparticles with narrow size distribution. Using relatively long thiol-ended alkane chains for the functionalization modifies the electronic density of stat…
Real-space imaging with pattern recognition of a ligand-protected Ag374 nanocluster at sub-molecular resolution
2018
High-resolution real-space imaging of nanoparticle surfaces is desirable for better understanding of surface composition and morphology, molecular interactions at the surface, and nanoparticle chemical functionality in its environment. However, achieving molecular or sub-molecular resolution has proven to be very challenging, due to highly curved nanoparticle surfaces and often insufficient knowledge of the monolayer composition. Here, we demonstrate sub-molecular resolution in scanning tunneling microscopy imaging of thiol monolayer of a 5 nm nanoparticle Ag374 protected by tert-butyl benzene thiol. The experimental data is confirmed by comparisons through a pattern recognition algorithm t…
Preparation and Investigation of Interfaces of Co2Cr1−x Fe x Al Thin Films
2013
In the framework of spin polarization investigations of Heusler compounds by the measurement of the magnetoresistance (TMR) of tunneling junctions with AlO x barrier special emphasis is put on the role of the interfaces.
Polymorphism of Two-Dimensional Halogen Bonded Supramolecular Networks on a Graphene/Iridium(111) Surface
2017
bibtex: ISI:000393443200020 bibtex\location:'1155 16TH ST, NW, WASHINGTON, DC 20036 USA',publisher:'AMER CHEMICAL SOC',type:'Article',affiliation:'Sicot, M (Reprint Author), Univ Lorraine, CNRS, Inst Jean Lamour, UMR 7198, BP 70239, F-54506 Vandoeuvre Les Nancy, France. Sicot, Muriel; Kierren, Bertrand; Fagot-Revurat, Yannick; Moreau, Luc; Granet, Julien; Malterre, Daniel, Univ Lorraine, CNRS, Inst Jean Lamour, UMR 7198, BP 70239, F-54506 Vandoeuvre Les Nancy, France. Tristant, Damien; Gerber, Iann C., Univ Toulouse, CNRS, INSA, LPCNO,UPS, 135 Ave Rangueil, F-31077 Toulouse, France. Tristant, Damien, Univ Toulouse, CNRS, CEMES, UPR 8011, 29 Rue Jeanne Marvig,BP 94347, F-31055 Toulouse, Fran…
Carrier transport mechanism in the SnO(2):F/p-type a-Si:H heterojunction
2011
We characterize SnO(2):F/p-type a-Si:H/Mo structures by current-voltage (I-V) and capacitance-voltage (C-V) measurements at different temperatures to determine the transport mechanism in the SnO2:F/p-type a-Si:H heterojunction. The experimental I-V curves of these structures, almost symmetric around the origin, are ohmic for vertical bar V vertical bar< 0:1 V and have a super-linear behavior (power law) for vertical bar V vertical bar < 0:1 V. The structure can be modeled as two diodes back to back connected so that the main current transport mechanisms are due to the reverse current of the diodes. To explain the measured C-V curves, the capacitance of the heterostructure is modeled as the …