Optical Radiation Interaction with Planar Metal Nano-Structures
Complex Investigation of Low-Intensive Optical Radiation Interaction with Aspherical Metal Nanoparticles and Their Planar Structures Ordered in Various Manners
Tech Area / Field
- INF-ELE/Microelectronics and Optoelectronics/Information and Communications
- PHY-OPL/Optics and Lasers/Physics
- PHY-SSP/Solid State Physics/Physics
8 Project completed
Senior Project Manager
Rybakova T A
B.I. Stepanov Institute of Physics, Belarus, Minsk
- Russian Academy of Sciences / Physical Technical Institute, Russia, St Petersburg\nMoscow State University / Department of Chemistry, Russia, Moscow\nNational Academy of Sciences of the Republic of Belarus / Institute of Molecular and Atomic Physics, Belarus, Minsk\nVavilov State Optical Institute (GOI), Russia, St Petersburg
- Uneversitat Gesamthochschule Kassel/Institut fuer Mikrostrukturtechnologie und Analytik, Germany, Kassel\nUniversity of Tokyo / Graduate School of Frontier Sciences, Japan, Tokyo\nUniversity of Lund / Department of Physics, Sweden, Lund\nNASA / Goddard Space Flight Center / Goddard Institute for Space Studies, USA, New York\nUniversity of California / Department of Physics and Astronomy, USA, CA, Irvine
Project summaryThe Project objective.
The objective of the Project is to clarify, on the basis of manifold theoretical and experimental investigations, the distinctive features of interaction of the low-intensity electromagnetic radiation (LIER) of optical range with the planar metal-containing nanostructures (PMNS) for purposes of their use in optics and nanoelectronics.
The objects for the investigation are the planar nanostructures of different surface topologies, which are smooth metallic coatings or those formed by the ensembles of metal clusters having spherical and nonspherical shape and characterized by different packing density and position/orientation ordering.
The other important problem to be solved in the Project is to set up the correlation between the optical, electrical, and structural parameters of these objects.
The experimental results on LIER reflection, transmission, absorption, and scattering of light will be analyzed with consideration of size, charge, polarization, and resonance effects. Microstructure of the fabricated samples will be studied by means of electron and atomic force microscopy, and X-ray photoelectron spectroscopy and diffraction, Auger electron spectroscopy, prophylometry. Electrical characteristics of granulated metal films (volt-ampere characteristics and temperature dependence of conductivity) will be measured and analyzed by which the impact of structure ordering on the electron transport behavior will be revealed.
The results of conducted investigations will constitute the basis for:
– the development of new optical elements, highly reflective mirrors with low optical scattering loss and selective optical filters;
– progression of high-performance optical methods for nondestructive nanostructures diagnostics applied in optics and nanoelectronics (used both at the stage of structure fabrication and for a post-fabrication control);
– the design of new optical systems for fast readout of information stored at super-high-density nanostructure-based memory sells.
The scope of the present Project comprise the fundamental research on the optical and electrical properties of nanostructures which is aimed at the development of new technologies of nanostructures manufacturing and diagnostics.
The distinctive Project feature is the combination of theoretical and experimental studies carried out on the basis of:
– the availability of the technology for the fabrication of metal-containing planar nanostructures with different topologies, different granule shapes, packing density and degree of their ordering, including the granulated films with up-to-date limiting granules density in a monolayer, up to 2×1012 cm-2;
– the possibility to perform wide-range measurements of various structural parameters of the fabricated objects;
– the possibilities to conduct perse measurements of optical and electrical characteristics of the nanostructures;
– the availability of the basic theoretical models and the program libraries for describing the optical and electrical properties of the objects.
In the Project frame, it is for the first time proposed to carry out the theoretical and experimental studies of the impact of electric charge residing at nanostructure granules on the light scattering characteristics in visible spectral range. The other new approach is to use near-field optical microscope for the studying the local light scattering characteristics at planar nanostructures.
The majority of experimental investigations of the optical and electrical properties of nanostructures will be taken on the equipment available or adapted to the problems in question.
Justification and usefulness of the work.
Interest in investigation of electromagnetic radiation interaction with PMNS is dictated by tremendous progress of technologies producing the structures with characteristic size of inhomogeneities of the order of several nanometers and with high packing density of metallic grains. These nanostructures are very promising for super-high-density information storage and for development of novel optical elements (one example is highly reflecting mirrors possessing the characteristics considerably improved with respect to those of conventional elements based on the supersmooth metallic surfaces). On the other hand, we emphasize a great potential of optical methods for the express nondestructive control of nanostructures parameters.
It should be noticed that despite the growing body of the investigations on the optical properties of metallic nanostructures, these studies could be described as limited and nonsystematic. The elaborated theoretical models taking into account the size dependence of optical constants are restricted to the analysis of transmission spectra in the structures comprising only isolated metallic particles, in some cases forming the ordered structures. In addition, nowadays approaches do not describe the spectral, angular, and polarization characteristics of scattered radiation. For densely packed structures the features of light scattering characteristics, space and orientation (for nonspherical particles) ordering effects remain to be indistinct. The existing theoretical models dealing with LIER scattering by rough surfaces are not sufficiently effective and can not describe all perse topologies of the planar nanostructures and supersmooth metallic mirrors. The transport properties of the metal-dielectric nanostructures have been investigated for a long time; however, the impact of different sources of structure disorder on the conductivity of these materials still has not been clarified. In particular, the adequate theoretical treatment of the random charge state of the granulated metal films is absent. The important question about conceivable correlation between the optical and electrical properties of nanocomposites has not been considered as well. To gain the knowledge in all the above directions of nanostructure physics is the particular aim of this Project.
The problem of special interest, not highlighted up to now, is the influence of nanoparticle’s charge state on the optical properties of granulated films. Finding of this correspondence would provide a new approach to controlling the optical parameters of the nanostructures and, in turn, to obtain important information on the random charge distribution that determines the fundamental characteristics of electron tunneling and transport in such structures. The solution of this problem, which is also the subject of the Project, should result in development of new nanostructure diagnostic tools. The consequence of these studies will be also the elaboration of novel nanoelectronics devices.
In view of this there is a great demand to put forward the systematic experimental and theoretical investigations of the optical and electric properties of metal nanostructures and to find the correlation between these properties. To our opinion, the suggested group of researchers may most successfully resolve the scope of problems proposed in the Project.
Scientific novelty and technical features.
The scientific novelty of the Project proposed lies in development of the profound aspects of the theory of LIER interaction with the PMNS of different topologies. The essential novelty of the proposed theoretical approach is the consistent consideration of metal particle size and shape, packing density, ordering, and charge effects upon LIER scattering characteristics. A novel quasi-hydrodynamic model of electron transport in metal-dielectric nanostructures will be developed that accounts for nonuniform and time-dependent charge density distribution deduced from self-consistent solution of continuity equations and Poisson equation.
The novelties in optical experiments are:
– complex optical characterization of planar metal nanostructures (with wide variation of structures parameters), fabricated from different materials and deposited on different substrates;
– the investigation of charge effect on the local scattering characteristics of the granulated metal nanostructures in the visible spectral range by using new technical approaches and equipment for near-field optical registration of scattering radiation.
Execution of the Project includes the solution of the following problems:
– The development of a theory describing adequately the optical properties of PMNS and supersmooth metallic mirrors.
– Fabrication of planar nanostructures (metal, metal-dielectric) and supersmooth Al, Au, Ag, Cu mirrors; control of their structural characteristics by means of electron and atomic-force microscopy, X-ray scattering and photoelectron spectroscopy, and Auger-spectroscopy.
– Experimental investigations of angle and polarization dependent LIER scattering characteristics in broad spectral range as well as the studies of absorption in nanostructures by the photoacoustic technique with regard to polarization.
– Theoretical and experimental investigations of the electrical characteristics of thin nanostructure films.
– Modification of the experimental setups for optical studies including construction of specialized unit for near-field scanning optical microscope (on the basis of atomic force microscope) for investigation of scattering characteristics of the nanostructures.
– Theoretical and experimental investigations of the granules charge effect upon the light scattering characteristics.
The methods, apparatus, and technologies devised in the course of some military programs will be utilized in the frame of the Project. The teams participating in the Project contain highly skilled scientists (6 Doctors of Science, 9 Candidates of Science) as well as experienced technicians and graduate students. High scientific level of the research groups is evidenced by their scientific publications and by participation at numerous International conferences.
Results to be expected.
In the course of the Project we plan to provide new insight into the nature of LIER interaction with PMNS and to analyze their prospects for applications. In particular:
– The new theoretical models describing the complete set of LIER scattering characteristics by nanostructures (with regard to size effect and collective effects) will be elaborated. New models of the tunnel electron transport in metal-dielectric nanostructures will be developed.
– The database containing the optical, electrical, and structural characteristics of PMNS will be created.
– The correlation between the optical and electrical nanostructure parameters will be established, and new techniques for nanostructure characterization will be demonstrated.
– The PNMS with high reflectivity and low scattering loss in ultraviolet and visible spectral ranges will be obtained.
– The technology for fabrication of selective optical filters (for ultraviolet and visible spectral ranges) on the basis of new-generation nanostructures will be proposed.
– The nondestructive techniques to control the structure parameters and charge conditions of PMNS will be suggested.
Execution of the whole complex of experimental and theoretical investigations proposed in this Project should result in the development of novel optic elements, new technologies for nanostructure manufacturing and diagnostic, as well as in elaboration of the new concepts for designing of nanoelectronics devices.
The role of collaborators.
The intention of foreign collaborators to take part in the Project realization is confirmed by the appropriate documents. All the collaborators are top-rank specialists in the areas covered by the Project. Their role is implementation of the Project tasks is expected to be very important. In due course of the work close contact with collaborators will be maintained for the exchange of ideas, current research results, and computation programs. Some experimental measurements can also be done on the cooperative basis.