A. A. Pavlov

Thermodynamics of the formation of catalyst clusters for carbon nanotube growth

A fundamental thermodynamic model of formation of catalyst clusters for growing carbon nanotubes has been developed and model predictions have been compared with the experimental data. An expression for the size distribution function of clusters, depending on the conditions of their formation, is obtained. It is shown that surface tension plays an important role in the cluster formation. The surface tension coefficient for iron clusters at 950°C is determined.

Development of matrix photoreceivers based on carbon nanotubes array

The technology of production of matrix photoreceivers based on carbon nanotubes (CNTs) consisting of 16 sensitive elements was developed. Working wavelength range, performance and sensitivity were studied.

Studying the field emission cathode–gate structure based on carbon nanotubes for electron-optical systems with a sheet beam

Results of studying the cathode–gate structure based on carbon nanotubes (CNTs) are presented. Experimental samples of a matrix field emission cathode–gate structure based on a vertical array of CNTs with a cell diameter of 1 μm and microstructure period of 5 μm have been manufactured. Based on experimental data, an electron-optical system with a ribbon-type field emission CNT based cathode with a linear convergence of 6.25 and beam-current density of 4.46 A/cm2 has been proposed. Results of modeling a sheet 0.16-mm-thick electron beam formed by an electron gun with a CNT cathode demonstrated the possibility to obtain a low-perveance flow with a small deformation in the 0.3 × 0.8-mm beam tunnel of a slow wave 25-mm-long structure.

Modelling of emission processes in carbon nanotubes

The field emission characteristics of an ideal carbon nanotube are simulated. A comparison of the characteristics of the tubes with the closed and open ends is performed. The simulation results are compared with the experimental measurement of the field emission current of a single carbon nanotube. The calculated and experimental field emission currents are in good agreement between.

Use of thin film of a Co15Ti40N35 alloy for CVD catalytic growth of carbon nanotubes

It is shown that multiwalled carbon nanotubes can be grown on the catalytic surface of a Co–Ti–N alloy with low (~10 at %) cobalt content by the conventional method of chemical deposition from acetylene. Adding nitrogen to the composition of the Co–Ti contributes the formation of the TiN compound and extrusion of Co onto the surface where it makes a catalytic effect for CNT growth. It was found that the tubes begin growth at a temperature of 400°C. It is shown by studies using Raman spectroscopy that the quality of CNT improves with increasing temperature.

CVD growth of carbon nanotubes on thin-film Ni20Ti35N45 alloy catalyst

The possibility of forming carbon nanotube (CNT) arrays on a Ni–Ti–N catalytic alloy with low nickel content by chemical vapor deposition (CVD) is demonstrated. Adding nitrogen to the Ni–Ti alloy composition favors the formation of TiN compound and segregation of Ni on the surface, where it produces a catalytic effect on the CNT growth. It is found that, using CVD from acetylene gas phase at a substrate temperature of 650°C, a CNT array of 9-µm height can be grown for 2 min.

Effect of the morphology of CNT arrays on the current density of field-emitter matrices

Structured carbon-nanotube arrays synthesized in topological regions formed by electron-beam lithography are studied. The effect of the morphology and topology of the carbon-nanotube arrays on the emission characteristics of the structures being formed are considered.

Influence of the doping type and level on the morphology of porous Si formed by galvanic etching

The formation of porous silicon (por-Si) layers by the galvanic etching of single-crystal Si samples (doped with boron or phosphorus) in an HF/C2H5OH/H2O2 solution is investigated. The por-Si layers are analyzed by the capillary condensation of nitrogen and scanning electron microscopy (SEM). The dependences of the morphological characteristics of por-Si (pore diameter, specific surface area, pore volume, and thickness of the pore walls), which determine the por-Si combustion kinetics, on the dopant type and initial wafer resistivity are established.

Features of the reduction of graphene from graphene oxide

Features of the reduction of graphene from graphene oxide in media containing hydrazine hydrate, ethylene glycol, and hydrogen are studied. X-ray energy dispersive spectroscopy, Raman spectroscopy, and scanning electron microscopy data indicate that this process proceeds through the high-temperature annealing of graphene oxide in a hydrogen environment.

Formation of carbon nanotubes on an amorphous Ni25Ta58N17 alloy film by chemical vapor deposition

It is shown that it is possible to grow carbon nanotubes on the surface of an amorphous Ni–Ta–N metal alloy film with a low Ni content (~25 at %) by chemical deposition from acetylene at temperature 400–800°C. It is established that the addition of nitrogen into the Ni–Ta alloy composition is favorable for the formation of tantalum nitride and the expulsion of Ni clusters, which act as a catalyst of the growth of carbon nanotubes, onto the surface. From Raman spectroscopy studies, it is found that, as the temperature of synthesis is raised, the quality of nanotubes is improved.