Barabash M. Science development for the formation of functional nanomaterials using templates

Українська версія

Thesis for the degree of Doctor of Science (DSc)

State registration number

0521U100081

Applicant for

Specialization

  • 05.16.01 - Металознавство та термічна обробка металів

26-01-2021

Specialized Academic Board

Д 26.002.12

Public organization organization of veterans and graduates of the Institute of Energy Conservation and Energy Management of the National Technical University of Ukraine "Kyiv Polytechnic Institute named after Igor Sikorsky"

Essay

This dissertation is devoted to the study of such a problem of materials science as the formation and physical properties of spatially periodic structures (>10 nm) in thin films of amorphous carbon and copper on a dielectric substrate, as well as to the study of surface plasmon effects using the methods of thermally stimulated depolarization, scanning tunneling microscopy, absorption spectroscopy, and Raman spectroscopy. A new approach to the formation of electret templates upon the electrophotographic process is proposed, and an electret template with an area of 1 cm2 and a period of 2 μm was formed. A method and a technology for manufacturing two-dimensional periodic metal-dielectric structures by the template method using a light field with a period of 0.8-6 μm and a relief height of 3.5-650 nm were developed. It allows to obtain a significant increase in signal in the studies of analytes using absorption and Raman spectra. This is considered as one of the most promising areas of application of the template technology. It is shown that the optical resonances of thin copper films can be identified by radiation from glass substrates. The resonances of the films were identified by comparing the absorption and Raman spectra at different wavelengths of the exciting light. Among the samples with close absorption levels, the sample with the largest amplitude of the Raman signals had the maximum value of optical resonances. The possibility of controlling the Raman spectrum of the films using light was shown. A technology for the production of nanomaterials with a photo-induced structure based on thin films of amorphous carbon with a copper sublayer on a glass substrate was developed. The composition, structure, and morphology of a-C thin films on a glass substrate and on a copper sublayer were studied using Raman spectroscopy and absorption spectroscopy. Basing on the analysis of the obtained spectra for the composite (a-C:Cu), it was found that this film had an amorphous-like matrix, the structure of which was determined by a thin layer of copper. Non-thermal changes in the color, size, and shape of the exposure spot in the (a-C:Cu) composite under impact of light were detected. This effect can be explained by the electron-phonon interactions in the films of the (a-C:Cu) composite. It is shown that the adatoms of gold nuclei make up a significant fraction of the total number of atoms. It is determined that after the condensation from the vapor the gold nanoclusters are in liquid state, and their movement along the AMS surface and the formation of aggregates of nanoclusters (aggregation) occur. This process occurs under the action of the electrostatic field of ions localized in the dielectric polymer matrix. The influence of the electric field on the nucleation during deposition of gold on AMS is shown. This occurs both at the stage of growth of nuclei due to the transfer of atoms on the surface and in the solid phase of AMS, and as a result of the transport of components in the gas phase in the electric field of the template. As a result, there is a selective nucleation and growth of gold nanoparticles on the AMS surface with a size exceeding 10 nm. A platform for sensorics based on thin layers of amorphous carbon on copper is developed with the implementation of double amplification as a result of the effect of charge transfer and the local field increase. Thin films of amorphous carbon with copper sublayer on a glass substrate, which have plasmon-resonant effects, are fabricated. The composition, structure and morphology of these films are studied using the methods of Raman and adsorption spectroscopy in the visible range. It is found out that the obtained spectra characterize the structure of the film as amorphous one. The developed adaptive software-hardware complex based on the amorphous molecular semiconductors also allows real-time recording of optical holograms. Computer methods for processing digital speckle interferometry and holographic interferometry data with the construction of phase portraits of products were developed. Investigations of the samples with heat-resistant coatings were carried out. This allowed to develop a method of non-destructive quality control of coatings using the dispersion of phase portrait. Key words: nucleation, phase formation, thermal sputtering, nanocomposite, nanoclusters, electret templates, amorphous carbon, thin film, electrophotographic method, Raman scattering, plasmon resonance.

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