Field emission from Luttinger liquids and single-wall carbon nanotubes

We develop a theory for the field emission effect in Luttinger liquids and single-wall carbon nanotubes at the level of the energy resolved current distribution. We generalise Fowler-Nordheim relations. Just below the Fermi edge, we find a power-law vanishing current distribution with the density of states exponent. The current distribution above the Fermi edge owes its existence to a peculiar interplay of interactions and correlated tunnelling. It displays a non-trivial power-law divergence just above the Fermi energy.Comment: 4 pages, 2 figures (eps files

Geometrical Dependence of High-Bias Current in Multiwalled Carbon Nanotubes

We have studied the high-bias transport properties of the different shells that constitute a multiwalled carbon nanotube. The current is shown to be reduced as the shell diameter is decreased or the length is increased. We assign this geometrical dependence to the competition between electron-phonon scattering process and Zener tunneling.Comment: 4 pages, 4 figure

Determination of the Intershell Conductance in Multiwalled Carbon Nanotubes

We report on the intershell electron transport in multiwalled carbon nanotubes (MWNT). To do this, local and nonlocal four-point measurements are used to study the current path through the different shells of a MWNT. For short electrode separations $\lesssim$ 1 $\mu$m the current mainly flows through the two outer shells, described by a resistive transmission line with an intershell conductance per length of ~(10 k\Omega)^{-1}/$\mu$m. The intershell transport is tunnel-type and the transmission is consistent with the estimate based on the overlap between $\pi$-orbitals of neighboring shells.Comment: 5 pages, 4 figure

Paradox of low field enhancement factor for field emission nanodiodes in relation to quantum screening effects

We put forward the quantum screening effect in field emission [FE] nanodiodes, explaining relatively low field enhancement factors due to the increased potential barrier that impedes the electron Fowler-Nordheim tunneling, which is usually observed in nanoscale FE experiments. We illustratively show this effect from the energy band diagram and experimentally verify it by performing the nanomanipulation FE measurement for a single P-silicon nanotip emitter (Φ = 4.94eV), with a scanning tungsten-probe anode (work function, Φ = 4.5eV) that constitutes a 75-nm vacuum nanogap. A macroscopic FE measurement for the arrays of emitters with a 17-μm vacuum microgap was also performed for a fair comparison

Hydrogen passivation of boron acceptors in as-grown boron-doped CVD diamond epilayers

A homoepitaxial boron-doped diamond single layer is investigated by means of Fourier transformed infrared spectroscopy (FTIR) and cathodoluminescence (CL). Both techniques are shown to be complementary. μ-FTIR mapping allows to determine the location of active boron while CL allows discernability between passivation and compensation. Hydrogen incorporation during chemical vapour deposition (CVD) growth is revealed to passivate boron acceptors. The obtained results highlight that plasma etching can induce a dissociation of B–H centres.4 page

Multi-particle effects in non-equilibrium electron tunnelling and field emission

We investigate energy resolved electric current from various correlated host materials under out-of-equilibrium conditions. We find that, due to a combined effect of electron-electron interactions, non-equilibrium and multi-particle tunnelling, the energy resolved current is finite even above the Fermi edge of the host material. In most cases, the current density possesses a singularity at the Fermi level revealing novel manifestations of correlation effects in electron tunnelling. By means of the Keldysh non-equilibrium technique, the current density is calculated for one-dimensional interacting electron systems and for two-dimensional systems, both in the pure limit and in the presence of disorder. We then specialise to the field emission and provide a comprehensive theoretical study of this effect in carbon nanotubes.Comment: 22 pages, 8 figures (eps files

The Physicist's Guide to the Orchestra

An experimental study of strings, woodwinds (organ pipe, flute, clarinet, saxophone and recorder), and the voice was undertaken to illustrate the basic principles of sound production in music instruments. The setup used is simple and consists of common laboratory equipment. Although the canonical examples (standing wave on a string, in an open and closed pipe) are easily reproduced, they fail to explain the majority of the measurements. The reasons for these deviations are outlined and discussed.Comment: 11 pages, 10 figures (jpg files). Submitted to European Journal of Physic

Field-effect transistors assembled from functionalized carbon nanotubes

We have fabricated field effect transistors from carbon nanotubes using a novel selective placement scheme. We use carbon nanotubes that are covalently bound to molecules containing hydroxamic acid functionality. The functionalized nanotubes bind strongly to basic metal oxide surfaces, but not to silicon dioxide. Upon annealing, the functionalization is removed, restoring the electronic properties of the nanotubes. The devices we have fabricated show excellent electrical characteristics.Comment: 5 pages, 6 figure

Effect of Substrate Morphology on Growth and Field Emission Properties of Carbon Nanotube Films

Carbon nanotube (CNT) films were grown by microwave plasma-enhanced chemical vapor deposition process on four types of Si substrates: (i) mirror polished, (ii) catalyst patterned, (iii) mechanically polished having pits of varying size and shape, and (iv) electrochemically etched. Iron thin film was used as catalytic material and acetylene and ammonia as the precursors. Morphological and structural characteristics of the films were investigated by scanning and transmission electron microscopes, respectively. CNT films of different morphology such as vertically aligned, randomly oriented flowers, or honey-comb like, depending on the morphology of the Si substrates, were obtained. CNTs had sharp tip and bamboo-like internal structure irrespective of growth morphology of the films. Comparative field emission measurements showed that patterned CNT films and that with randomly oriented morphology had superior emission characteristics with threshold field as low as ~2.0 V/μm. The defective (bamboo-structure) structures of CNTs have been suggested for the enhanced emission performance of randomly oriented nanotube samples