E. O. Popov

Evolution of the characteristics of a field-electron emitter based on nitrocellulose-carbon nanotube composite

Characteristics of a field-electron emitter based on a nitrocelulose-multiwalled carbon nanotube composite have been studied. A new method of the recording and online processing of current-voltage (I–U) characteristics of multipoint field-electron emitters has been developed for monitoring the evolution of their properties. Using this method, we have (i) determined the dependences of the field enhancement factor and number of emission centers on the interelectrode distance, (ii) discovered hysteresis of the I–V curve related to variation of the amplitude of applied voltage pulses, and (iii) revealed the influence of the initial emission current level on the temporal evolution of emitter properties.

Statistical dispersion of the field emission parameters of multipoint cathodes based on a polymer-carbon nanotube composite

Statistical properties of the characteristics of a field-electron emitter based on a polystyrene-carbon nanotube composite have been studied. Experimental data have been used to plot the slope versus intercept of I-U curve in the Fowler-Nordheim coordinates and a histogram of the effective heights of emission centers. Numerical estimations show that this statistics obeys the lognormal distribution law. A series of experiments have been performed for determining the influence of the level of emission current on the character of distribution, and a model describing this dependence is proposed.

Multiple-tip liquid-metal field emitter

A stable field emitter with a large tip density (up to 108 cm−2) has been created using track membrane technology. The emitter has been tested in various current collection regimes from a constant current to short pulses of nanosecond duration with a repetition frequency of several kilohertz. The high stability of the emission current at moderate electronic current densities up to 100 mA/cm2 is attributed to the presence of a large number of emitting tips and the dynamic equilibrium between the repulsive forces of the electric field and the forces due to surface tension.

UV photostability of PMMA-C60 fullerene composition

Thermal decomposition of pure poly(methyl methacrylate) (PMMA) and its composition with C60 fullerene before and after UV irradiation has been studied by thermodesorption mass spectrometry (TDMS). It is established that low-temperature depolymerization of UV-irradiated PMMA is suppressed in its composition with C60. Possible molecular stabilization mechanisms are discussed.

Hysteresis phenomenon of the field emission from carbon nanotube/polymer nanocomposite

Using the high voltage scanning method and the technique of multichannel recording and processing of field emission (FE) characteristics in real time mode we found out some subtle effects on current voltage characteristics (IVC) of the multi-tip field emitters. We observed the direct and reverse hysteresis simultaneously in the same field emission experiment. Dependence of the form of IVC hysteresis on time of high voltage scanning was observed.

Fine structure of the thermal decomposition kinetics of polymethylmethacrylate filled with detonation nanodiamonds

A comparison has been made of the specific features of the fine structure of thermodesorption spectra of polymethylmethacrylate and its composites with nanocarbon fillers: detonation nanodiamonds, fullerene C60, and multiwalled carbon nanotubes. The influence of the fillers on the shape of the thermodesorption spectra has been interpreted as a result of the chemical interaction between functional groups of macromolecules of the polymer matrix and active centers of filler nanoparticles.

A study of the electrical properties of the porous GaP (111) surface

Local electrical properties of the surface of porous GaP have been measured by the method of tunneling spectroscopy in ultrahigh vacuum. Two surface areas with different electrical properties were found. The effect of anomalous field-induced photoemission was observed. The most probable reason for this effect is the presence of Ga2O3 and GaP nanoclusters and the high density of acceptor-type surface states associated with these clusters. Integral characteristics of the field electron emission from the sample surface were obtained by using a computerized recording system with online processing of current–voltage characteristics.

Application of slope-intercept diagram to determine the parameters of the nanocomposite field emitters in-situ

The method of the field emission data online processing of materials, perspective for a nanoelectronics, is developed. The method is based on the slope-intercept diagram analysis of the current voltage characteristics registered during the experiment. It allows to build calibration grids of the microscopic emission parameters, such as work function, effective emission area and field enhancement factor, and and to estimate changes in the sample structure online.

Field electron emission from flat metal cathodes covered by thin polymer films

We have studied the physical properties of a new class of field electron emitters representing metal cathodes covered by thin polymer films based on a soluble imide-siloxane copolymer. Polymer coating leads to an increase in the emission current and provides for a quite stable field electron emission of flat polished molybdenum and niobium cathodes.

The technique of field emission parameters research for nanostructured materials improvement

A new technique was developed to record and in situ process the data on the evolution of multiwall carbon nanotubes polymer (MWCNT-polymer) nanocomposite field emitters. It includes multichannel acquisition system of current voltage characteristic (IVC), vacuum level, temperature and mass-spectrum data with computer on-line processing of these data based on the LabVIEW program. We obtained the time dependence of the field enhancement factor, the number of emission sites and kinetics of main volatile products during field emission process.