Field emission

Thin films of nanocrystalline cubic AlN were synthesized by vapor–liquid–solid (VLS) route on Si and fused silica substrates at appropriate conditions. The formation of cubic AlN was confirmed by X-ray diffraction studies. We also observed that AuCl3 plays an important role as a catalyst in the synthesis of well crystalline cubic phase of AlN. Energy dispersive analysis of X-rays confirmed

The discovery of carbon nanotubes by Iijima in 1991 has created a torrent of new research activities. Research on carbon nanotubes ranges from studying their fundamental properties, such as their electron band structure and plasma frequencies, to developing new applications, such as self-assembled nano-circuits and field emission displays. Robust models are now needed to enable a better understanding of the electronic response of carbon nanotubes. We use timedependent density functional theory to derive a two-fluid two-dimensional (2D) hydrodynamic model describing the collective response of a multiwalled carbon nanotube with dielectric media embedded inside or surrounding the nanotube. We study plasmon hybridization of the nanotube system in the UV range, the stopping force for ion channelling, the dynamical image potential for fast ions, channelled diclusters and point dipoles, and the energy loss for ions with oblique trajectories. Comparisons are made of results obtained from th...

Electron beam (e-beam) fabrication of nanostructures by transmission electron microscopy (TEM) is rapidly developing into a top-down nanofabrication method for the sub-5 nm fabrication of structures that cannot usually be realised using resist based lithographic techniques or by the focused ion beam patterning methods. We describe the usage of a variety of e-beam shapes, including point and elliptical line focus, as well as a comparison of LaB6 and field-emission guns (FEGs), to achieve versatile sculpting of nanodot arrays, nanobridges and nanotips. We operate our patterning on free-standing nickel (Ni) thin film laterally connected to a silicon (Si) substrate as well as to free-standing Ni nanotips, where we achieve a novel three-dimensional (3D) nano-sculpting methodology.

 Abstract— Field emission properties of the structured carbon nanotube cathodes were investigated by field emission scanning microscopy, scanning electron microscopy and integral field emission measurements with luminescence screen. The carbon nanotube arrays were synthesized by the atmospheric pressure floating catalyst chemical vapour deposition method under the high temperature pyrolysis of ferrocene/xylene solution. Varying arrays of carbon nanotube columns and blocks were fabricated on Si, SiO 2 and porous anodic alumina substrates. Well-aligned field emission from nearly 100% of the patches at electric field <10 V/µm in direct current and pulsed mode integrally and locally was observed. High current capabilities up to mA currents for structured carbon nanotube cathodes were achieved. Integral field emission measurements with luminescence screen and processing under N 2 and O 2 exposures of up to 3×10 −5 mbar demonstrated homogeneous current distribution and long-term stability of the structured carbon nanotube cathodes. Index Terms— carbon nanotubes, field emission catchodes, structured carbon nanotube arrays, field emission scanning microscope.

Carbon nanotubes (CNTs) have novel electronic and mechanical properties and they are promising materials for future technological applications [1]. Electronic properties and electronic energy band structure of CNTs have been calculated for tubes with all equal graphitic C–C bond ...

The ZnO nanowires have been synthesized using vapor–liquid–solid (VLS) process on Au catalyst thin film deposited on different substrates including Si(1 0 0), epi-Si(1 0 0), quartz and alumina. The influence of surface roughness of different substrates and two different environments (Ar + H2 and N2) on formation of ZnO nanostructures was investigated. According to AFM observations, the degree of surface roughness of the different substrates is an important factor to form Au islands for growing ZnO nanostructures (nanowires and nanobelts) with different diameters and lengths. Si substrate (without epi-taxy layer) was found that is the best substrate among Si (with epi-taxy layer), alumina and quartz, for the growth of ZnO nanowires with the uniformly small diameter. Scanning electron microscopy (SEM) reveals that different nanostructures including nanobelts, nanowires and microplates have been synthesized depending on types of substrates and gas flow. Observation by transmission electron microscopy (TEM) reveals that the nanostructures are grown by VLS mechanism. The field emission properties of ZnO nanowires grown on the Si(1 0 0) substrate, in various vacuum gaps, were characterized in a UHV chamber at room temperature. Field emission (FE) characterization shows that the turn-on field and the field enhancement factor (β) decrease and increases, respectively, when the vacuum gap (d) increase from 100 to 300 μm. The turn-on emission field and the enhancement factor of ZnO nanowires are found 10 V/μm and 1183 at the vacuum gap of 300 μm.▶ Our work has demonstrated that the surface roughness of substrate is an important parameter in final formation of the deposited ZnO nanostructure. ▶ The role of the different substrates and two types of the carrier gas flow on the growth of ZnO nanowire were investigated. ▶ Si substrate was found to be the best substrate for the growth of ZnO nanowires with small and uniform diameter and regular shape. ▶ The field emission property of the ZnO nanowires grown on Si substrate without epi-layer was studied under UHV conditions at room temperature for different cathode–anode separation distances. The obtained experimental data are well agreed with the Fowler–Nordheim theory.