The fabrication of nanotube field emitters with an onset field as low as 0.8 V/μm is described and the low-field electron emission mechanism is discussed. These emitters are made using nanotube cathode deposit with the addition of epoxy resin. The preferred orientation of nanotubes in nanotube bundles of the deposit is preserved. The nanotube tips are sharpened by exposing the nanotube bundle surface to a microwave oxygen plasma. The local-field enhancement factor is estimated to be 8000 by using the Fowler–Nordheim equation. The low onset field is attributed to the well-distributed, highly orientated sharp tips at the sample surface.

Electron beam lithography was used to fabricate silver nanoparticle arrays and study the effects of geometrical properties of particles on metal-enhanced fluorescence. Nanoparticle size, shape, interparticle spacing, and nominal thickness were varied in a combinatorial pattern for investigation of the particle plasmon resonance effect on enhancement of fluorescence from three different fluorophores; Fluorescein, Cy3, and Cy5. A specific geometric property for optimal enhancement from each fluorophore was determined. For interparticle spacings greater or equal to 270 nm, the enhancement matched what is expected for a single-particle model. For those particles smaller than 210 nm, the enhancement was lower than for the larger spacing in the range studied. Triangular-shaped particles gave similar enhancement to those of square-shaped particles. This combinatorial pattern by e-beam lithography was found to be useful for studying how individual parameters enhance the fluorescence that are important for rational design of enhanced fluorescence sensors.

Using the measured capacitance-voltage curves of Ni Schottky contacts with different areas on strained AlGaN∕GaN heterostructures and the current-voltage characteristics for the AlGaN∕GaN heterostructure field-effect transistors at low drain-source voltage, we found that the two-dimensional electron gas (2DEG) electron mobility increased as the Ni Schottky contact area increased. When the gate bias increased from negative to positive, the 2DEG electron mobility for the samples increased monotonically except for the sample with the largest Ni Schottky contact area. A new scattering mechanism is proposed, which is based on the polarization Coulomb field scattering related to the strain variation of the AlGaN barrier layer.

No abstract

We systematically investigate the resonant behavior of arrays of Ag nano-structures ranging from isolated simple rods, to U-shapes, to single split ring structures. We show that the lowest order plasmonic resonance associated with a rod red shifts as we create a U and SRR into the position normally associated with a simple LC mode. A second mode red shifts and grows in intensity as we extend the arms of the U-shape, and a third mode appears in the spectra as we close the arms and form a split ring structure. We performed simulations of the structures and examine the E-field and current density. The simulations show that the current path is different for these modes. We examine the behavior of the lowest order mode in detail, discuss the effects of skin depth, and present an improved LC model to describe this resonance.

Nanocrystalline diamond films have been synthesized by microwave plasma enhanced chemical vapor deposition using N 2 /CH 4 as the reactant gas without additional H 2. The nanocrystalline diamond phase has been identified by x-ray diffraction and transmission electron microscopy analyses. High resolution secondary ion mass spectroscopy has been employed to measure incorporated nitrogen concentrations up to 8ϫ10 20 atoms/cm 3. Electron field emission measurements give an onset field as low as 3.2 V/m. The effect of the incorporated nitrogen on the field emission characteristics of the nanocrystalline films is discussed.

All instances of IR should read iR.The second sentence in the first full paragraph on page E45 should cite Ref. 20 as follows:The films were grown with much better control over the quality than were the CH 4 /N 2 films reported on previously. 20The sentence beginning on the sixth line of the first paragraph under the heading ''Results and Discussion'' ͑page E45͒ should read No significant difference in the macroscopic morphology was observed for the films deposited from CH 4 /Ar with and without N 2 added, at least up to the 5% level.The last sentence in the paragraph subheaded ''Electrochemistry'' ͑page E47͒ should read Even with the incorporated nitrogen, the films do not appear to possess significant numbers of reactive sites where electroactive surface carbon-oxygen functionalities form.The paragraph which begins on page E47 and ends on E48 should include the following sentence at the end of the paragraph Note that these i-E curves were not corrected for any iR effects. In addition, the background current between Ϫ500 and 1000 mV, after extensive scanning, does increase with increasing nitrogen incorporation.The second sentence in the second full paragraph on page E49 should readThe rate of electron transfer is insensitive to surface modification with the strong implication that electron transfer does not depend on an interaction with a surface site or functional group. 35 The fourth sentence in the fourth full paragraph on page E49 should read Quasi-irreversible voltammetric behavior ͑⌬Ep's from 60 to 90 mV at 0.2 V/s͒ is typically observed for both MV ϩ2 /MV ϩ and MV ϩ /MV0 redoc couples having formal potentials of Ϫ725 and Ϫ1050 mV vs. SCE, respectively.The last sentence in this paragraph should readThe relatively low ⌬E p of 50 to 60 mV for nitrogen-incorporated nanocrystalline diamond indicates these electrodes contain a high density of bandgap electronic states, even at these negative potentials, and that adsorption may be occurring.The second sentence in the second full paragraph on page E50 should read Films deposited from 1% CH 4 /4% N 2 /95% Ar on W substrates were tested.

We study the enhancement of fluorescence by Ag nanopillars on a semiconducting substrate in which the pillar size, shape, and spacing is varied systematically using electron-beam lithography. Local maxima in the enhancement versus lateral size, as large as a factor of ∼20 are observed, and vary both with the shape of the pillars and the wavelength of the excitation. We find that the size, shape, and spacing dependence is in qualitative agreement with a model based upon resonant coupling with particle plasmon polaritons. We also find increased enhancement for particle shapes producing high local electric fields.