Fyzikální ústav Akademie věd ČR

Seminář Pondělí, 10.06.2013 11:00 - 11:50

Přednášející: Nikolay Galkin (Institute of Automation and Control Processes FEB RAS, Vladivostok, Russia)
Místo: Knihovna FZÚ, Cukrovarnicka 10, Praha 6
Jazyk: anglicky
Pořadatelé: Oddělení optických materiálů

Formation of nanosize (5–30 nm) dots of Fe, Cr, Ca, Mn and Mg silicides on Si(111)7x7 and Si(100)2x1 surfaces, silicon growth atop nanosize silicide dots and multilayer repetition of developed growth procedure for all silicides have been carried out in ultra-high vacuum chambers. Optimization of growth parameters has permitted to create monolithic multilayer nanoheterostructures (NHS) with buried nanocrystals (NCs) of Fe, Cr and Mn disilicides and polycrystalline NHS with buried Ca3Si4 and Mg2Si NCs or two-dimensional layers. It was shown that beta-FeSi2, CrSi2 NC and Mg2Si (5-30 nm) are elastically embedded in silicon lattice due to introduction of tension in the NC lattice and silicon lattice around NC without formation of misfit dislocations on the interface. An increase of the conductivity in the low temperature range was observed for Si/Mg2Si/Si(111) NHS with embedded Mg2Si nanocrystals (10-30 nm) and two-dimensional (2D) Mg2Si layer with thickness 1.0-2.0 nm. Models of conductivity processes through the silicon layer with embedded Mg2Si NCs and 2D Mg2Si layer have been proposed. The electronic structure and morphology of calcium silicide films formed by reactive deposition epitaxy at 130oC on Mg2Si film and at 500oC on Si(111)7x7 surface, their optical and electrical properties have been investigated. The formation of new calcium silicide phase with high Si concentration (Ca3Si4), indirect band gap (0.63 eV), high conductivity at low temperatures (50-450 K) has been obtained after calcium deposition at 500 oC on Si(111)7x7 surface. Formation of semiconducting Mn silicide (MnSi1.74) with 0.32 eV band gap was found, when Mn atoms were deposited on the Si(111)-2×2-Fe phase. Electrical, thermoelectrical and electroluminescence properties of multilayer NHS, silicide films and mesa-diodes with NHS were studied and perspectives of light emitting diodes and thermoelectric converters for photonics and thermoelecronics were discussed.