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Properties of Composites Based on Nanostructured Metal-Oxides

#B-1724


Photoelectrical and Optical Properties of Composites Based on Nanostructured Metals in a Matrix of Oxy Compounds in the Infrared Spectral Region

Tech Area / Field

  • INS-DET/Detection Devices/Instrumentation
  • MAT-COM/Composites/Materials
  • PHY-OPL/Optics and Lasers/Physics
  • PHY-SSP/Solid State Physics/Physics

Status
3 Approved without Funding

Registration date
11.02.2009

Leading Institute
B.I. Stepanov Institute of Physics, Belarus, Minsk

Supporting institutes

  • Belarussian State University / Institute of Physical Chemical Problems, Belarus, Minsk\nRussian Academy of Sciences / Physical Technical Institute, Russia, St Petersburg\nMoscow State University / Department of Chemistry, Russia, Moscow

Collaborators

  • Universite Montpellier II / Institut d'Electroniwue du Sud, France, Montpellier\nVilnius University / Institute of Materials Science and Applied Research, Lithuania, Vilnius\nUniversity of California / Department of Physics and Astronomy, USA, CA, Irvine

Project summary

The purpose of the Project is to reveal theoretically and experimentally the features of steady-state and transient photoconductivity and optical properties of the composites consisting of nanostructured metals (or bimetals) in metal-oxide and hydroxide matrixes in the IR spectral range. The results of studies are supposed to be applicable in optoelectronics, optics and nanophotonics. The main problem to be solved in the Project is to elucidate the nature and mechanisms of long-wave shift of photoconductivity inherent to thin film nanostructured composites which depends on the geometrical sizes and composition of the nanostructured metal clusters, recombination processes probability and peculiarities of the charge transfer kinetics. The correlations between absorption, luminescence spectra, spectral sensitivity of the photoconductive systems and structural characteristics of composites are important purpose to be solved in the Project. Optical constants of inpidual components, multiple scattering, polarization state, collective and nonlinear effects should be taken into consideration. Optical constants of oxides and hydroxides in the IR spectral region are great parameters to be determined for the interpretation and prediction of optical and photoelectric characteristics of nanostructured composites.

Situation in the field of research.

The interest in investigation of the optical and photoelectrical properties of the composites like oxide – oxide, dye- oxide, and metal - oxide in IR spectral range is being governed by search for composites that are promising to fabricate the effective IR detectors and optics components with improved characteristics as compared to the composites currently available. Rather little data there currently exist concerning photoconductivity of the structures made of island -like metal-oxide films in red and near IR spectral bands. The same situation has been occurred with optical constants of oxides in IR that are required for optical properties prediction of oxidized metal nanostructures. At the same time the conductivity and some specific features of optical parameters of oxidized granular metal containing nanostructures in the near IR have been observed. The following effects are relevant to be noticed: absorption maximum long-wave shift for oxidized copper nanostuctures, maximal absorbance of the nanostructured monolayer is observed at metal-oxide ratio equal to 0.5, enhanced photoluminescence of oxide is revealed nearby the metal particles, nonlinearity of optical properties. Theoretical calculations of the near-field electromagnetic amplitude together with photoluminescence studies give evidence that the «hot dots» really exist. This is a reason of absorbance noticeable increase that plays the key role in the photoconductivity observation. Amplitude of electromagnetic radiation in “hot dots” can many orders of magnitude exceed the amplitude of incident radiation and it depends on the gradient of electromagnetic field nearby the metal particle. Thus, the nanostructured metals organized in specific manner inside the metal oxy-compound matrixes are expected to play an active role in effective generation and tunneling of free carrier under the action of electromagnetic radiation. Hence, the value of photo-stimulated conductivity in IR spectral range can be controlled via changing the structures of semiconductor oxy-compound and nanostructured metallic component. The oxide matrix in the systems under consideration will serve not only as a source of effective generation of free carrier near the metal particles, but also as a protector of small metal particles against harmful oxidation, aggregation and enlargement and consequently against the loss the characteristics desired. Therefore the problems to solve in the Project are directed to determination of the unknown optical constants of oxides and hydrioxides in the IR spectral band. New understanding of the nature and origin of photoconductivity as well as optical properties of composites from nanostructurized metals or bi-metals in oxy-compound matrixes are supposed to be obtained.

The influence of the suggested Project on progress in the area under consideration. Usage of properly organized metal nanostructures in the metal oxides and hydroxides matrixes seems to be new approach in material science. New knowledge of photoconductivity of the nanostruturised metal / oxy-compound composites, optical constants and properties determination of the materials early unknown are believed to give rise to progress in nanophotonics, optoelectronics, optics.

The participants of the Project: The State Scientific Institution “B.I. Stepanov Institute of Physics of the National Academy of Sciences of Belarus”, Research Institute for Physical Chemical Problems of Belarusian State University, Ioffe Physical-Technical Institute of the Russian Academy of Sciences, Chemistry Department of Moscow State University.The realization of the Project will allows to a large group of scientists earlier involved in programs of military nature (codes 1,2,5) to turn to civil fundamental and applied investigations.

Expected results:

  • New knowledge of the nature and mechanisms of the long-wavelength shift of photosensitivity inherent to nanostructured components in oxy-compound matrixes will be received. The optical constants of unexplored materials in IR spectral range will be determined.
  • Theoretical model of thin film composite photoconductivity will be derived. New physical models describing optical properties of mono- and multi-layered composites will be elaborated.
  • Optical properties of early unexplored composites on the base of nanostructured metals or bimetals l / oxy- compound and the features of steady-state and transient photoconductivity in the IR spectral range will be established.
  • The correlations between absorption, luminescence spectra, spectral sensitivity of the photoconductive systems and structural characteristics of composites will be found out.

Practical significance of the Project includes the following items:
  • Technology will be developed for composites fabrication having photoconductivity and absorption in IR spectral range.
  • Methods for optical characterization of composites and their inpidual components will be worked out;
  • New technology for IR filters production will be developed.
  • Anticorrosion metal-oxide coating with small reflection and scattering, high degree of the blackness in the near IR spectral range as compared to composites now available will be worked out.

The new approach working out for long-wavelength shift of photosensitivity to IR spectral range, the nature and mechanism of composite photoconductivity revealing and determination of optical constants and optical properties of unexplored composites and oxy-compounds in IR spectral range are of fundamental significance.

Project results application. Practical problems to solve in the Project are development of structurally stable systems production, that exhibit steadiness against aging, low cost and ecological safety for needs of nanophotonics, optoelectronics, and optics. Owing to high corrosion stability of coatings and photoconductive properties of composites that are expected to be applicable for IR spectral range they are of interests for photodiodes, photomultipliers, filters, protective and anti-reflective coatings fabrication and promise a lot of advantages as compared to composites now available. The series of the materials and methods of their production elaborated in the Project are expected to be the items of patenting.. The scientific products the licensing will be possible as well, the addition licensing and permission not required.

Meeting ISTC Goals and Objectives The Project fulfilment offers the possibility for large group of scientists, which had been deeply involved in military researchers, to switch over to nonmilitary scientific subjects. The research directed to revealing of the nature and mechanism of composite photoconductivity and determination of optical constants and optical properties of early unexplored composites and oxy-compounds in IR spectral range are of fundamental significance. Practical tasks that will be solved in the Project are concerned with the development environmentally friendly technologies and materials for optics, nanophotonics and optoelectronics and material science. Scientific, technological, and methodological basis, which will be created within framework of Project, will provide the Project participants with a long-term perspective of their activity in civil field, namely in optoelectronics and physics of nanostructures. The Project’s goal is to prevent spreading out of special knowledge and technology in the field of mass destruction weapon development and production. This is in line with the aims and objectives of ISTC.

Scope of Activity. The project duration is supposed to be 36 months, total project effort give 10630 person days which uniform distributed in years and quarters. All conceivable organizations will participate in development of composites production and establishment of correlation between absorption, luminescence, photo-electric properties of composites and their structural parameters. The theoretical and experimental investigations of composite photo-conductivity and optical properties will be carry out.

Role of Foreign Collaborators. Close and direct ties will be established with collaborators, with the purpose: the ideas and current results exchange, basic theoretical models exchange, joint experimental investigations on collaborator set.

Technical Approach and Methodology. Physical and chemical methods such as laser electrodispersion, metal reduction from solutions, sol-gel technology, the local 1-D and 2-D modification of nanostructures by multi-spectral pulsed laser of nanostructures will be used for composites production of the required properties. Steady-state and pulsed photoconductive characteristics of composites will be studied by the direct contact techniques, as well as by contact-free method of transient gratings and photo-electro-chemical method. The nature and mechanisms of long-wavelength shift of photoconductivity inherent to thin film nanostructured composites will be studied with the taking into account the geometrical sizes and composition metal nanostructured clusters, recombination processes and free charge transfer. Experimental investigation of spectral, angular and polarization properties of transmission, reflection, scattering and luminescence will be used for the optical characterization of physical and chemical properties of composites and their inpidual components. Together with the results of theoretical modeling will be used for determining optical constants of oxy-compounds in IR spectral region. The approaches developed by participants and the elaborated calculation programs will be extended and applied to the IR region. New physical models describing optical properties of mono- and multi-layered composites will be elaborated with taking into account the structure of metal and bimetal particles and their assemblies, their ordering and etc.


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