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Volume 7, Issue 4(Suppl) J Nanomed Nanotechnol
ISSN: 2157-7439 JNMNT, an open access journal
Page 72
Nano Congress 2016
August 01-02, 2016
conferenceseries.com
August 01-02, 2016 Manchester, UK
9th Nano Congress for Next Generation
Semiconductor quantum cones: Unique source of photons and electrons
Arturs Medvids
Riga Technical University, Latvia
Nanostructures are one of the most investigated objects in semiconductor physics, especially due to quantum confinement effect
in quantum dots (0D), quantum wires (1D) and quantum wells (2D). A new laser technology elaborated for quantum cone
formation in semiconductors is reported. A cone possesses the following unique properties: A small cone with angle α=60o at the
top of the cone is a quantum dot – 0D, when α=0o is transformed to a quantum well – 2D and when a long one with α<60o is
transformed to a quantum wire – 1D with the gradually decreasing diameter from the base till the top of the cone. Luminesce of
such a quantum cone resembles rainbow. Where radii in cone are equal or less than Bohr’ radius of electron, exciton or phonon
Quantum Confinement Effect (QCE) takes place. Quantum cones on the surface of elementary semiconductors Si and Ge single
crystals, and Si1-xGex (x=0.3 and x=0.4) solid solution were formed by fundamental frequency and second harmonic of Nd:YAG
laser radiation. Strong change of the optical, mechanical and electrical properties of the semiconductors after irradiation by Nd:YAG
laser are explained by the presence of QCE in quantum cones. “Blue shift” of photoluminescence spectra and “red shift” of phonon
LO line in Raman spectrum are explained by exciton and phonon QCE in quantum cones, correspondently. Asymmetry of the
photoluminescence band in the spectrum of Si quantum cones is explained by formation of graded band gap structure. Experimental
data on quantum cones formation on a surface of Si, Ge crystals and their solid solution and their optical and electric properties
are presented. Two-stage model of quantum cones’ formation on the irradiated surface of the semiconductors is proposed. The first
stage of the cones formation is characterized by the formation of a thin strained top layer, due to the redistribution of point defects in
temperature-gradient field induced by strongly absorbed by laser radiation. As a result, p-n junction and hetero junction are formed
in Ge crystal and SiGe solid solution, correspondently. The second stage is characterized by mechanical plastic deformation of the
stained top layer leading to arising of quantum cones due to laser heating up of the top layer. Si quantum cone possesses the lowest
work function of electron field emission due to graded band gap structure.
Self-construction from 2D to 3D: One-pot layer-by-layer (LbL) assembly of Graphene Oxide (GO) sheets held
together by coordination polymers
2Mohamed B Zakaria and 1Yusuke Yamauchi
1Faculty of Science and Engineering, Waseda University, 3-4-1 Okubo, Shinjuku, Tokyo, 169-8555, World Premier International (WPI) Research Center for Materials
Nanoarchitechtonics (MANA), 2National Institute for Materials Science (NIMS), 1-1 Namiki, Tsukuba, Ibaraki 305-0044, Japan.
For further development of functional materials, a smart construction of functional 2D materials to well-defined 3D constructions
is crucial. The best strategy in this line is a layer-by-layer (LbL) assembly that can provide well-designed alternate layered structures
in nanoscale precision from a variety of functional components. Here, we demonstrate a novel synthetic strategy which entails
deposition of Ni-based cyanide bridged coordination polymer (NiCNNi) flakes on the surface of Graphene Oxide (GO) sheets, and
allows precise control of the resulting lamellar nano-architecture by in-situ crystallization. GO sheets are utilized as nucleation sites
promoting the optimized crystal growth of NiCNNi flakes. The NiCNNi-coated GO sheets then self-assembled and are stabilized
as ordered lamellar nanomaterials. This approach might be applied to many other inorganic-organic hybrids for ordered layer-by-
layer (LbL) architectures. Regulated thermal treatment under nitrogen yields Ni3C-GO composite with a similar morphology to
the starting material. The Ni3C-GO composite exhibits outstanding electro catalytic activity with strong durability for the oxygen
reduction reaction.
J Nanomed Nanotechnol 2016, 7:4 (Suppl)