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Integrated field-emission devices and integrated circuits (ICs) based on them are a promising direction in microelectronics, which is associated with the use of low-voltage and stable field ...emitters based on nanomaterials, such as carbon nanotubes (CNTs). The planar design of the field-emission device makes it possible to form CNTs at the end of a thin catalyst film 1–50 nm thick. The paper presents the results of the implementation of an integrated technology for manufacturing planar field-emission diodes with a CNT cathode formed at the end of a thin conducting film. The CNTs are grown by chemical-vapor deposition. A thin film of initially amorphous Co–Nb–N–(O) alloy is used as the growth catalyst. A feature of the technology is the crystallization of Co–Nb–N–(O) alloy during heating in the process of chemical-vapor deposition. As a result, Co nanoparticles are formed on the alloy surface, which catalyze the growth of CNTs. It is shown that this specific feature makes it possible to form CNTs locally, only in open areas of the Co–Nb–N–(O) alloy, for example, at the ends of a thin film. The choice of the Co–Nb–N–(O) alloy is substantiated. The stages of formation of planar field-emission diodes on a silicon substrate are described using standard manufacturing processes. The results of measuring the
I
–
V
characteristics of devices are presented. It is shown that the type of
I
–
V
characteristics is determined by the field emission characteristic of CNTs. The developed technological method for the local synthesis of CNTs at the ends of topologically formed regions of a thin Co–Nb–N–(O) alloy film can be incorporated into an integrated technology for the formation of planar field-emission devices.
Abstract
In this work, a method for the formation of planar supercapacitors, which combines electrophoretic deposition of composite electrode materials based on CNTs and ruthenium oxide, and laser ...engraving, is proposed. The features of electrophoretic deposition are considered and the influence of the main technological modes on the morphology and composition of the formed layers of electrode materials is determined. The conducted studies of the electrophysical characteristics of the formed samples confirmed the possibility of producing planar capacitors with a high capacity and their potential applicability for a number of applications in microelectronics.
Abstract
This work shows the possibility of forming a planar diode structure based on carbon nanotubes formed on a catalytic alloy film Co-Nb-N-(O). The paper presents a technological route for the ...formation of a planar diode structure Si/SiO
2
/Si
3
N
4
/Co-Nb-N-(O)/SiO
2
and studies the emission characteristics. The current-voltage characteristic of the obtained diode structure in the Fowler-Nordheim coordinates is close to linear in the range from 15 to 22 V, which confirms the phenomenon of electron emission.
A laser technology for producing conductive film and bulk composites is proposed. The composites are made from calcium phosphate and albumin biopolymer permeated by a network of carbon nanotubes. ...Exposure of the areas of composite films produced from dispersions with nanotube concentrations of 0.1 and 1 mg/mL to pulsed radiation at a wavelength of 1064 nm made it possible to obtain the maximum conductivity of 21 and 100 mS·m
−1
at a radiation power of 3 and 2.4 W, respectively. The maximum increase in the conductivity by a factor of 3.3 was obtained after laser treatment of a film based on a dispersion with the nanotube concentration of 0.1 mg/mL. The maximum number of percolation nodes in the bulk network of nanotubes in a dielectric matrix of calcium phosphate and albumin was achieved by exposure to continuous radiation with a wavelength of 810 nm and a power of 9 W for 80 minutes. The conductivity of composite films was close to that of human cortical bone, while the conductivity of bulk composites exceeded that of human cortical bone by 3-4 orders of magnitude. The technology presented in this work can find application for the cultivation of bone cells and/or regeneration of bone tissues by electrical stimulation.
The work studies the synthesis of carbon nanotubes by chemical vapor deposition using a thin-film nickel-based catalyst. The size distributions of all catalyst nanoparticles are compared with the ...distribution of particles from which carbon nanotube growth is observed. It is established that in this mode nanotubes grow mainly from particles of 7 to 19 nm, and nanotubes rarely grow from particles outside this size range. A thermodynamic model of the solubility of carbon in nickel nanoparticles is developed and it is shown that for each set of parameters of the synthesis process there is a critical minimum size of the catalyst nanoparticle in which carbon can dissolve.
In this paper we have demonstrated the possibility of the MWCNT growth on initially amorphous Co–Zr–N–O alloy thin film which was crystallized during heating followed by formation of Co particles on ...the surface. It was found that during CVD not only the growth of usual MWCNT array but also the formation of MWCNT arrays with a top covering layer and bilevel MWCNT arrays take place. The details of MWCNT array growth process are discussed. We have found that carbon nanotubes growth strongly depends on the Co concentration in the alloy film. The presented technique of MWCNT growth can be used in the preparation of new advanced engineering materials.
—The synthesis of carbon nanotubes by chemical-vapor deposition (CVD) using a thin-film nickel-based catalyst is studied. An analysis of the size distributions of catalyst nanoparticles is carried ...out and compared with the distribution of particles from which the growth of carbon nanotubes is observed. The experiment shows that carbon nanotubes grow mainly from particles with sizes from 7 to 19 nm; nanotubes do not grow from particles of other sizes. A thermodynamic model of the solubility of carbon in a nickel nanoparticle is developed. This theoretical model is based on minimizing the Gibbs free energy of the system of nanoparticles that appear after the catalyst film melts. A critical minimum size of the catalyst nanoparticle exists for each set of parameters of the synthesis process, such that, under these conditions, it is able to dissolve a carbon atom.
A technique for obtaining carbon nanotubes (CNTs) doped with nitrogen in ammonia plasma has been developed. In this technique, CNTs synthesized by a method excluding their doping with nitrogen are ...post-treated in ammonia plasma. This treatment leads to a more than fivefold increase in the concentration of nitrogen (from 0.7 to 3.6 at %), a sixfold decrease in the resistance, and a 10% decrease in the work function of CNTs, resulting in stabilization of the process of cold electron emission.
The features of electrophoretic deposition process of composite LiCoO2-based cathode and Si-based anode materials were researched. The influence of the deposition process parameters on the structure ...and composition of the deposit was revealed. The possibility of a local deposition of composites on a planar lithium-ion battery structure was demonstrated.
A study using a set of physicochemical methods has shown that treatment of single-wall carbon nanotubes synthesized by the electric arc method with an aqueous solution of hydrogen peroxide (followed ...by treatment with hydrochloric acid) and with a mixture of concentrated nitric and sulfuric acids leads to a decrease in the content of inorganic impurities in the bulk of the finished materials. The acid oxidizing mixture shows the highest performance in the process, causing splitting of the bundles of single-wall carbon nanotubes into separate nanotubes and formation of stable concentrated suspensions of the nanotubes in water and in an isopropanol–water mixture. Both kinds of liquid-phase oxidative treatment enhance the electrical conductivity of the nanotube arrays and exert no pronounced selective effect on single-walled carbon nanotubes depending on the electronic conductivity of molecules of this material.
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