A. I. Zhbanov

Thin films consisting of carbon nanotubes as a new material for emission electronics

The investigation results for the emission characteristics of thin films composed of nanotube carbon structures are described. These films are shown to provide high field electron emission and substantial thermal electron emission even at low temperatures. They exhibit low electron work functions and ensure stable field emission under conditions of operating vacuum.

Rotation of the inner shell in a C20@C80 nanoparticle

The stability of a C20@C80 nanoparticle and the rotation of its inner shell are studied theoretically within the tight-binding approximation. It is found that the C20 skeleton in the free state is described by space group D3d; in the case where C20 is placed into the C80(Ih) fullerene field, the space group of C20 is raised to Ih due to isomerization. The total energy surface of the C20@C80 compound is scanned over two rotation angles. Based on an analysis of the surface relief and energy isoline map, orientational melting of the nanoparticle is predicted. A nanoparticle gyroscope—C20 rotating in the field of C80 at a certain relative orientation and energy supply—is also predicted to exist.

Two‐stage distributed amplifier on field emitter arrays

A two‐stage distributed microwave amplifier with field emitter arrays is analyzed. It is shown to be capable of operating in the millimeter wavelength band and to provide better performance as compared with reported amplifier designs.

Analysis of the possibility of performing microelectronic microwave vacuum devices with extended interaction on field emitter arrays

The possibility of microminiature microwave vacuum devices with extended interaction to be designed on the base of field emitter arrays is considered theoretically. The optimal designs of planar slow‐wave systems on dielectric substrates and of edge field emitter arrays electron guns for such systems are defined. High coupling resistances achieved in the above structures with low acceleration voltages in a wide frequency range and electron beams formed with suitable electron trajectory spread prove the assimilation of microwave range to be possible by such devices, including the millimeter‐wavelength band.

Investigation of limit current density for film carbon nanocluster field emitter arrays

The effect of carbon film destruction during field emission has been revealed in the course of the first investigations of this field emission material. The main field emission centers for film carbon field emitter arrays (FEAs) are their nanocluster tops where electric field intensities are achieved which are necessary for emission. We have theoretically studied the temperature field of a film whose nanotubes are placed on a silicon substrate with the same spacings from each other. The nanotubes have identical heights and diameters. Calculation was performed using the method of finite elements.

Distributed microwave amplifier on field emitter arrays with a nonhomogeneous energy collector

The nonlinear characteristics of a new type of electrically tuned distributed amplifier on field emitter arrays are considered that involve an energy collector in the form of a periodically nonhomogeneous strip line. In contrast to standard amplifiers, this collector exhibits a higher gain and operates at lower currents.

Analysis of the possibility of performing microminiature low-voltage electron devices for vacuum millimeter-wavelength integral circuit

The output characteristics of a strip distributed microwave (MW) power amplifier tuned by voltage in a wide frequency range analyzed. New energy collector designs are proposed to be employed in the amplifier in the form of a periodically nonuniform strip line and electron optical system comprising an electron gun with the multi-edge field emitter array current modulator. Their electrodynamic and current parameters have been calculated by rigorous methods. The analysis of the output amplitude-frequency characteristics of the amplifier was performed. It is shown that, unlike the previously reported amplifier design, it can allow for a higher gain in the short-wavelength region of centimeter band, including the millimeter band, or operate at substantially lower beam currents.

To the study of mechanism of nanotube film growth on the Fe catalyst

This paper reports the synthesis of carbon nanotube films on a flat substrate. The Fe catalyst is previously deposited on the substrate as a solid film with thickness reaching 10 nm. At the first stage of growth nanotubes pushed up the whole iron film but then due to the difference in the speed of growth, the catalyst film is broken to large patches.

Investigation of the basic physical phenomena taking place during field emission from carbon nanotube films

Summary form only given. Field emission from nanotube film is accompanied by a number of phenomena occurring both inside film and at its surface. Every of them influence on field emission properties and the cathode lifetime. In the present report the peculiarities of electron transport inside nanotube films under the influence of electric and thermal fields are considered. The geometry changes of nanotubes during field emission which lead to nanotube work function variations are estimated. The threshold field value, at which nanotube breakdown has been obtained. The possibility of surface states presence at the film/vacuum interface is examined. Special attention as paid to the fluctuation spectrum analysis of emission current, which come from the relaxation oscillations of separate emission centers. This analysis allows one to study the details of electron transport inside films, and shows the ways to decrease the cathode noises. The main results of investigation of thermal processes that occur during field emission in different carbon macromolecules are also given in the report. Joule heat release from nanotubes, is studied in details, Nottingham and Peltier effects are considered, and heat conduction and radiation of nanotubes were taken in account. Carbon nanotube heat conduction coefficient vs. their diameter, chirality and number of layers is theoretically investigated.

Analyzing of the characteristics of low-voltage multibeam mean-power electro-vacuum distributed MW amplifier with transverse interaction on the base of multielectrode electron-optical system with a matrix graphite field emitter array

This paper considers a two-stage distributed multibeam microwave amplifier containing a high-voltage multielectrode electron gun with a matrix graphite FEA and two identical two-dimensionally periodical WISs designed as a multistage ladder structure in a rectangular waveguide. The analyzed results are presented for the electrodynamical characteristics of the waveguide and electron-optical systems.