Jong Wan Park

Formation of low-resistance ohmic contacts between carbon nanotube and metal electrodes by a rapid thermal annealing method

The contact resistance between a carbon nanotube and metal electrodes decreases by several orders of magnitude and becomes long-term stable when the nanotube contacted by Ti-Au electrodes was annealed by a rapid thermal annealing method at 600-800 °C for 30 s. The contact resistances of the annealed samples are in the range 0.5-50 kΩ at room temperature, depending on the electrical properties of the nanotube. The short and relatively low-temperature annealing process enables us to make a surface Ti-nanotube contact suitable for electrical measurements. For the samples with relatively low contact resistances (0.5-5 kΩ) at room temperature, the contact resistance remained constant or decreased slightly as the temperature was lowered. Those with a relatively high contact resistance (5-50 kΩ), on the other hand, showed increasing contact resistance with a lowering of the temperature.

Fano resonance in crossed carbon nanotubes

We report the observation of the resonant transport in multiwall carbon nanotubes in a crossed geometry. The resonant transport is manifested by an asymmetric peak in the differential conductance curve. The observed asymmetric conductance peak is well explained by the Fano resonance originating from the scattering at the contact region of the two nanotubes. The conductance peak depends sensitively on the external magnetic field and exhibits Aharonov-Bohm-type oscillation.

Surface Plasmon Nanooptics in Plasmonic Band Gap Structures: Interference of Polarization Controlled Surface Waves in the Near Field

Nanoscopic emission from periodic nano-hole arrays in thick metal films is studied experimentally. The experiments give direct evidence for SP excitations in such structures. We show that the symmetry of the emission is governed by polarization and its shape is defined the interference of SP waves of different diffraction orders. Near-Held pattern analysis combined with the far-Held reflection and transmission measurements suggests that the SP eigenmodes of these arrays may be understood as those of ionic plasmon molecules.

Correlated Electrical Transport through Multiwall Carbon Nanotubes in a Crossed Geometry

The electrical transport properties of two multiwall carbon nanotubes in a crossed geometry were studied. Each carbon nanotube exhibited differential conductance vanishing with the power of bias voltage. The power-law dependence of the differential conductance was attributed to the Tomonaga-Luttinger liquid behavior of the carbon nanotube, which is considered to be a one-dimensional conductor. The differential conductance curve of one of the two carbon nanotubes was affected significantly by constant bias voltage applied to the other carbon nanotube. The characteristic features of the change of the differential conductance curve we have observed are in good agreement with the theoretical predictions for the two crossed Tomonaga-Luttinger liquids which are expected to exhibit correlated electron transport.

Phase-coherent conduction in mesoscopic normal-metal/superconductor hybrid junctions

In this paper we report about the transport properties of mesoscopic normal-metal/superconductor (NS) hybrid systems with two different junction layouts. One is a junction fabricated by overlaying S on N wire and the other with S sandwiched between two N wires, forming an NSN structure. At zero bias all the junctions exhibited a sharp decrease of dV=dI; which is believed to arise from the interference between the disorder-scattered and the Andreev-reflected quasiparticles. A small magnetic field corresponding to one flux quantum through the normal metal region, applied in parallel with the NS junction, easily suppressed the anomalous zero-bias conductance enhancement for the sandwich-junction sample. This high sensitivity to a small magnetic field observed in our systems of mesoscopic NS junctions in a diffusive-transport regime directly confirms the electron‐holeinterference origin of the zero-bias anomaly. q 2000 Published by Elsevier Science Ltd. All rights reserved.

Inter‐Shell Hopping And Resonant Transport In Double‐Wall Carbon Nanotube

Electrical transport properties of individual double‐wall carbon nanotube (DWNT) are studied. Negative differential conductance (NDC) was observed for the DWNT with a defected outer shell. Such NDC was explained in terms of the resonant tunneling through multiple quantum dots. Also observed is the Fano resonance for the low‐resistance samples. The Fano resonance was manifested by asymmetric peaks in the gate modulation and also by the zero‐bias peak in the differential conductance curve. Both NDC and Fano resonance in DWNT demonstrates the interplay of inner and outer shells via the inter‐shell hopping of electrons.

Non-Local Transport in a Multi-Wall Carbon Nanotube

Non-local electric transport phenomena were observed for a multi-wall carbon nanotube. The magnetic field dependence of non-local resistance was out of phase with respect to the conventional four-probe resistance, which could be explained in terms of the Landauer-Buttiker formula. Our observations indicate that the phase coherence length of multi-wall carbon nanotube exceeds the voltage probe length of about 1.1 µm at the measured temperatures.

Positive and negative band gaps, Rayleigh-Wood's anomalies in plasmonic band-gaps structures

We report the first measurement of blue shifted plasmonic bandgap structures. Issues concerning the Rayleigh wavelength, Woods anomaly, surface plasmonic and Fabry-Perot resonances are clarified.

Transmission, control and coherent propagation of surface plasmons in metal nanostructures

Extraordinary transmission of light through sub-wavelength hole arrays in thick metals is imaged both at allowed and forbidden surface plasmon resonances. Detouring around the holes, coherent propagation along and beyond the hole patterns are revealed.

Phase-Coherent Electronic Transport in a Multi-Wall Carbon Nanotube

Non-local electric transport phenomena were observed for a multi-wall carbon nanotube. The magnetic field dependence of non-local resistance was out of phase with respect to the conventional four-probe resistance, which could be explained in terms of the Landauer-Buttiker formula. Our observations indicate that the phase coherence length of multi-wall carbon nanotube exceeds the whole sample length of 3.8 µm up to the measured temperature 18 K.