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Field emission of graphene is usually limited by the surface morphology because the existing deposition methods lead to graphene flakes that lay flat on the substrate. To overcome this problem, we synthesized polypyrrole(PPy)-graphene composites by electrochemical deposition method. The graphene flakes are oriented at some angles on the PPy surface, leading to good field emission performance. This...
Over these past years our team has been pioneering an original orientation which is the use of field emission (FE) as a probe of mechanically resonating nanotubes (NTs), nanowires (NWs) and recently graphene. The resonators and electrical environment can be considered to be a nano-electro-mechanical system (NEMS). My goal here is to promote this subject better within the FE community whereas it has...
Since the discovery of carbon nanotubes (CNTs), much attention has been paid to explore the use of one-dimensional nanomaterials as field emission electron cold cathodes. Now one may obtain electron emission at much low fields using the nano cold-cathodes and also can prepare vaccuum electron emitters in a self-assembly process. Many studies have been carried out in synthesis, characterization and...
This article reviews recent development of the vertically configured vacuum field emission integrated devices utilizing nanodiamond microtip emitters and their further implementation into circuits. The device design, fabrication and characterization of the nanodiamond vacuum field emission functional devices including transistor and triode are discussed. The realization of the basic circuit building...
The coherent cold field emission (CCFE) images have been observed by a number of experiments. As the well-defined cold field nano-emitters such as carbon nanotubes and graphene can be implemented today, it is meaningful to discuss a microscopic theory for the CCFE. We will present a path-decomposition approach that incorporates the electronic structure of the nano-emitter and the emission wave function,...
In this paper, we report our recent works on modeling of ultrafast laser induce electron emission from a sharp tip and recent progress about space-charge-limited (SCL) current. We first study the pulse shape effect on electron emission by solving the time dependent Schrödinger equation. Carrier envelope phase effect is analyzed. Later we develop a single electron model to study the space charge (SC)...
In the paper, we examine the validity of traditional electron models (e.g. field emission, thermionic emission and photoemission) for graphene, and then propose new electron emission mechanisms and models to account for the unique properties of graphene. Also, some applications based on novel emission mechanism are explored.
The case of an in-plane gated CNT emitter integrated in a planar diode configuration was investigated. An electrostatic model was proposed, which resulted in an analytical expression of the field at the apex of the CNT. Simulations validated this model and confirmed that the electrostatic influence of the bias electrode only depends on its radius and CNT height. The proximity of the gate as compared...
We received and compared the current-voltage characteristics (IVC) of the multi-tip field nanocomposite emitters in the slow and the fast high voltage scanning modes. We found two types of hysteresis on the emission characteristics plots in the same field experiment. The study of IVC form depending on the duration and amplitude of the scanning voltage was carried out.
This conference presentation is part of continuing work to clarify the theory of cold field electron emission (CFE). It addresses the issue that some general physics textbooks and many published experimental papers use one or more CFE equations that are known to CFE theoreticians to be defective. These defective equations have been in wide use for 15 years or more: they impede the interpretation of...
Focused Electron Beam Induced Processing allows to generate nanocrystalline materials with metallic conductivity and also nanogranular materials with metal crystals embedded in a fullerene matrix, which shows at room temperature 1000 times better conductivity than superconductors at 40 K due to a Bose Einstein Condensate. Resistors and field emitters carry > 50 MA/cm2 current density and deliver...
A semiclassical model based on the Landauer transmission theory and McKelvey's flux theory is constructed to describe the field electron emission from folded graphene with an internal biased voltage. This model, which has taken the unique electronic energy band structure of monolayer graphene into account, leads to the explicit expression for drain to source and field emission line current density...
We have examined the tunneling potential between two carbon nanotubes (CNTs) immersed in a dielectric matrix, with each pair of them being in a different geometrical configuration to each other. We have found that this potential may differ significantly from pair to pair even when the distance between them is the same and hence the transmission coefficient between CNTs is heavily dependent on geometrical...
In this work we study the long-term stability of surface nano-structures that may function as field emitters. For this purpose, we have developed a new Kinetic Monte Carlo model for the surface diffusion. We have found that copper tips with an aspect ratio of about 8 may be stable for hours at room temperature, but collapses already within a microsecond at temperatures above 800 K.
We developed a multi-scale time dependent density functional method to simulate electrons in semi-infinite long nano structures emitting into vacuum via the apex of nano structures. A relation between the field emission energy distribution and the angular momentum inside the single wall carbon nanotube is shown.
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