Semicond. Physics Quantum Electronics & Optoelectronics, 2015, № 3

Plasmon-enhanced fluorometry based on gold nanostructure arrays. Method and device

2017-06-14T00:07:44Z

Plasmon-enhanced fluorometry based on gold nanostructure arrays. Method and device Chegel, V.I.; Lytvyn, V.K.; Lopatynskyi, A.M.; Shepeliavyi, P.E.; Lytvyn, O.S.; Goltvyanskyi, Yu.V. In this work, we describe a method of surface-enhanced fluorometry, based on the phenomenon of localized surface plasmon resonance in unordered gold nanostructure arrays. The theoretical approach for the model system “gold nanoparticle-dielectric spacer” in the electrostatic approximation by solution of Laplace’s equation is considered. The developed technology for manufacturing the plasmonic substrates as well as design of the novel laser-based compact fluorometer are presented. The arrays of gold nanostructures on solid substrates (nanochips) coated with different thicknesses of SiO₂ were developed and fabricated by thermal annealing of gold island films with subsequent dielectric spacer deposition. As an example for verification of the proposed method, the fluorescence properties of the system “gold nanostructures array – SiO₂ dielectric coating – Rhodamine 6G” were studied. It has been shown that enhancement of dye emission up to 22 times for dielectric coating with the thickness of about 20 nm is possible. Presented method is of importance for the development of the novel nanoscale sensors, biomolecular assays and nanoplasmonic devices.

Superluminescent laser-integrated nanocarbonized matrix pumping the neodymium lasers YAG:Nd

2017-06-14T00:07:39Z

Superluminescent laser-integrated nanocarbonized matrix pumping the neodymium lasers YAG:Nd Onachenko, M.S. Forming of surface nanocarbonized structures on substrate, it is possible to reduce the series resistance of nanoregions contacts in heterostructures. It was achieved by increasing the efficiency and output power in nanocarbonized structures by 2 times with decreasing the heat release on successive contact resistance. We obtained improved parameters of nanocarbonized matrices for pumping after finding the possibility to create a new generation of neodymium lasers with semiconductor pumping without forced cooling. The obtained III-nitride AlGaInN/Si heterostructures instead of the AlGaAs/GaAs ones allow to more accurately select and grow the better chemical composition for the emitting region, the emission spectrum of which is closer to the radiation of a neodymium laser.

Impedance anisotropy and quantum photocapacity of bio/inorganic clathrates InSe〈histidine〉 and gase〈histidine〉

2017-06-14T00:07:33Z

Impedance anisotropy and quantum photocapacity of bio/inorganic clathrates InSe〈histidine〉 and gase〈histidine〉 Ivashchyshyn, F.O.; Grygorchak, I.I.; Klapchuk, M.I. Intercalated nanostructures of InSe〈histidine〉 and GaSe〈histidine〉 were formed. Phenomena of the negative capacitance and the quantum capacitance are visualized in the first nanostructure. The introduction of histidine between indium selenide layers leads to increasing of conductivity anisotropy ( σ|| σ⊥ ) from 67 to 226. Temperature dependences of the real component of the complex impedance indicate semiconductor mechanism of conductivity along nanolayers with two activation energies: 1.6 meV at low-temperature and 0.25 meV in high-temperature regions. Appearance of the giant high-frequency negative magnetoresistance and almost 20-fold photosensitivity increase are observed in the second nanostructure. The conductivity anisotropy of the nanostructure GaSe〈htd〉 ( σ|| σ⊥ ) is 10² . Temperature dependence of the real component of complex impedance along the layers at temperature regions –30 < t °C ≤ 10, 10 < t °C ≤ 30, 30 < t °C ≤ 50 demonstrates cardinally different mechanisms of conductivity. Activation energies are 0.35 meV in the low-temperature and 0.69 meV in high-temperature intervals. Non-activated conductivity mechanism is observed within the range of temperatures 10 < t °C ≤ 30. The parameters of the energy spectrum calculated using the Geballe-Pollak theory prior to and after introduction of histidine for two nanostructures are given; it well correlates with the experimental dates.

Theoretical and experimental study of Raman scattering in mixed (MoS₂)x(MoSe₂)₁₋x layered crystals

2017-06-14T00:07:29Z

Theoretical and experimental study of Raman scattering in mixed (MoS₂)x(MoSe₂)₁₋x layered crystals Yaremko, A.M.; Yukhymchuk, V.O.; Romanyuk, Yu.A.; Virko, S.V. Raman scattering in mixed MoS₂/MoSe₂ layer type crystals was investigated in this work. The change of intensities and positions of bands for in-plane E¹₂g and outof-plane A₁g vibrations as functions of the “concentration” inherent to corresponding type layers has been studied. Estimation of interlayer interaction was obtained from comparison of experiment and theory, and effect of this interaction on the frequency of intralayer phonon was studied.