>> Keynote Speech--Dr. Sigitas TAMULEVIČIUS
Plasma deposition of diamond like carbon based nanocomposites for optical and electrical applications
Diamond-like carbon (DLC) films is the subject of considerable attention due to their extraordinary properties such as low friction coefficient and high wear resistance; high corrosion resistance and chemical inertness; high electrical resistivity; infrared-transparency and high refractive index. Therefore, many applications of DLC films have already been implemented for practical use such as mechanical elements, optical components or biomaterials. Metal nanoparticle containing DLC films showing excellent potential in various practical applications attract much attention as well. The nanocomposite films containing the nanometer range sized noble metal nanoparticles of silver, gold or other metals like copper, embedded in a matrix such as amorphous carbon have been studied intensively, since such type of films exhibit surface plasmon resonance (SPR) and are promising materials for developing the elemental base of laser physics, opto- and micro-electronics devices. The unique optical properties of such nanostructured films in the visible region of the spectrum, are due to resonance bands of plasmon-polariton absorption and their characteristics depend on the filer and host material, on the size and shape of nanocrystallites and their concentration, and also on the morphology of the composite material. The incorporation of metal-dielectric composites in periodic structures enables combining the surface plasmon resonance and the resonance phenomena that take place in it.
In this work an overview of recently completed and ongoing research on optical and electrical properties of DLC deposited by reactive magnetron sputtering and novel applications of this material is presented. The results of theoretical and experimental investigation of the optical absorption spectra of thin films as well as piezoresistive properties of nanocomposite materials composed of silver nanoparticles embedded in a diamond like carbon matrix will be discussed. The results on structure, technological conditions relation to the gauge factor of DLC based nanocomposite piezoresistive sensor will presented. The optical characteristics of DLC-Ag nanocomposite were considered within the framework of the effective medium approximation. The evolution of plasmon resonance characteristics and optical properties with changes of dielectric constant of DLC host and size of embedded metal nanoparticles was studied. The observed experimental redshift and broadening of the surface plasmon resonance bands were explained using Mie scattering theory and Maxwell-Garnett effective medium theory. The obtained results suggest that a random mixture consisting of a DLC film with embedded isolated silver inclusions is promising material for the fabrication of tunable nanocomposites in different sensing platforms (including optical and piezo sensors) . Finally, to use the unique potential of periodic DLC-Ag nanocomposite-based structures systematic study on technology of deposition is necessary; optimization of their structural and optical properties enables to design and fabricate the diffractive optical elements for applications in various optical systems.