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Browsing Articole ştiinţifice by Author "URSAKI, V. V."

Browsing Articole ştiinţifice by Author "URSAKI, V. V."

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  • AB2X4 Compounds with Other Types of Structures at High Pressures 
    URSAKI, V. V.; TIGINYANU, I. M. (Springer-Verlag Berlin Heidelberg, 2014)
    Phase transitions in AIIBIII2XVI4 compounds with initial structures different from cubic spinel or tetragonal chalcopyrites and stannites are analyzed in this chapter on the instance of layered AIIInGaS4 crystals with Cd, ...
  • Anomalous retroreflection from nanoporous materials as backscattering by `dark' and `bright' modes 
    SERGENTU, V. V.; PRISLOPSKI, S. Ya.; MONAICO, E. V.; URSAKI, V. V.; GAPONENKO, S. V.; TIGINYANU, I. M. (IOP Publishing, 2016)
    In this paper the mechanisms of previously experimentally observed anomalous retroreflection in a strongly absorbing nanostructured medium are explained by using ‘dark’ and ‘bright’ modes. The observed regularities are ...
  • Artificial birefringence introduced by porosity in GaP 
    URSAKI, V. V.; SYRBU, N. N.; ALBU, S.; ZALAMAI, V. V.; TIGINYANU, I. M.; BOYD, Robert W. (IOP Publishing, 2005)
    Porosity-induced birefringence in a GaP membrane is studied using a method based on the analysis of beats in unpolarized and polarized transmittance spectra as well as in angular dependence of optical spectra. Birefringence ...
  • Birefringence and excitonic spectra of TlGaS2 crystals 
    STAMOV, I. G.; SYRBU, N. N.; URSAKI, V. V.; ZALAMAI, V. V. (ELSEVIER, 1999)
    The anisotropy of transmission spectra was investigated in TlGaS2 crystals. An intensive transmission line was found in samples placed between two crossed polarizers. Ground and excited states of excitons were detected in ...
  • Birefringence and excitonic spectra of TlGaS2 crystals 
    STAMOV, I. G.; SYRBU, N. N.; URSAKI, V. V.; ZALAMAI, V. V. (Elservier, 2013)
    The anisotropy of transmission spectra was investigated in TlGaS2 crystals. An intensive transmission line was found in samples placed between two crossed polarizers. Ground and excited states of excitons were detected in ...
  • Birefringence of CuGaxAl1-xSe2 crystals 
    SYRBU, N. N.; DOROGAN, A. V.; MASNIK, A.; URSAKI, V. V. (IOP Publishing, 2011)
    Excitonic reflection spectra of CuAlSe2 crystals were studied at 10 K. The spectral dependences of refractive indices no and ne were calculated. The isotropic wavelength (the point of intersection of no and ne) in the ...
  • Calculation of optical functions of exciton and electron transitions by means of Kramers-Kronig relations in CuAlS2 crystals 
    STAMOV, I. G.; SYRBU, N. N.; KORZUN, B. V.; URSAKI, V. V.; DOROGAN, A. V.; MASNIK, A. (Academy of Sciences of Moldova, 2013)
    Excitonic reflection spectra of CuAlS2 crystals were measured at a temperature of 10 K for E||c and Ec polarizations. The shapes of the lines of ground states of Г4 and Г5 excitons were calculated by means of the ...
  • Cathodoluminescence characterization of rare earth doped composite materials based on porous GaP 
    SÁNCHEZ, B.; MÉNDEZ, B.; PIQUERAS, J.; SIRBU, L.; TIGINYANU, I. M.; URSAKI, V. V. (Springer Nature Switzerland, 2008)
    Porous GaP layers doped with erbium or europium elements have been obtained by electrochemical etching and further impregnation processes. The thermal treatments for optical activation of rare earth (RE) ions lead to partial ...
  • Characterization of core/shell structures based on CdTe and GaAs nanocrystalline layers deposited on SnO2 microwires 
    GHIMPU, L.; URSAKI, V. V.; PANTAZI, A.; MESTERCA, R.; BRÂNCOVEANU, O.; SHREE, Sindu; ADELUNG, R.; TIGINYANU, I. M.; ENACHESCU, M. (ELSEVIER, 2018)
    We report the fabrication and characterization of SnO2/CdTe and SnO2/GaAs core/shell microstructures. CdTe or GaAs shell layers were deposited by radio-frequency (RF) magnetron sputtering on core SnO2 microwires synthesized ...
  • Characterization of structure and luminescence of titania nanotubes 
    ENACHI, M.; TROFIM, V.; COSEAC, V.; TIGINYANU, I. M.; URSAKI, V. V. (Institutul de Inginerie Electronică şi Nanotehnologii "D. Ghiţu" al AŞM, 2009)
    The morphology, structural, and optical properties of porous titania layers prepared by electrochemical oxidation of Ti foils are studied as a function of technological conditions of preparation and post-electrochemical-oxidation ...
  • Charge carrier distribution in free-standing porous GaP membranes studied by Raman spectroscopy 
    SARUA, A.; TIGINYANU, I. M.; URSAKI, V. V.; IRMER, G.; MONECKE, J.; HARTNAGEL, H. L. (ELSEVIER, 1999)
    Free-standing porous GaP membranes were fabricated by anodic etching of (111)-oriented crystalline substrates in H2SO4 aqueous solution. The formation of a column-shaped porous structure with average structure dimension ...
  • A comparative study of guided modes and random lasing in ZnO nanorod structures 
    URSAKI, V. V.; ZALAMAI, V. V.; BURLACU, A.; FALLERT, J.; KLINGSHIRN, C.; KALT, H.; EMELCHENKO, G. A.; REDKIN, A. N.; GRUZINTSEV, A. N.; RUSU, E. V.; TIGINYANU, I. M. (IOP Publishing, 2009)
    Hexagonal and arrow-headed ZnO nanorod structures have been grown by low pressure chemical vapour deposition (CVD) and atmospheric pressure metal-organic CVD. The technology ensures a high optical quality of the produced ...
  • Comparative study of hydrothermal treatment and thermal annealing effects on the properties of electrodeposited micro-columnar ZnO thin films 
    LUPAN, O.; PAUPORTÉ, T.; TIGINYANU, I. M.; URSAKI, V. V.; SONTEA, V.; ONO, L. K.; ROLDAN CUENYA, B.; CHOW, L. (ELSEVIER, 2011)
    We report a comparison of the role played by different sample treatments, namely, a low-temperature hydrothermal treatment by hot H2O vapor in an autoclave versus thermal annealing in air on the properties of ZnO films ...
  • Comparative study of the ZnO and Zn1−xCdxO nanorod emitters hydrothermally synthesized and electrodeposited on p-GaN 
    LUPAN, O.; PAUPORTÉ, T.; CHOW, L.; CHAI, G.; VIANA, B.; URSAKI, V. V.; MONAICO, E.; TIGINYANU, I. M. (ELSEVIER, 2012)
    Hydrothermal synthesis and electrodeposition are low-temperature and cost-effective growth techniques of high quality nanostructured active materials for opto-electronic devices. Here we report a hydrothermal seed layer-free ...
  • The contribution of exciton-phonon interaction and action disorder to near-band-edge extrinsic absorption in II-III2-VI4 compounds 
    GEORGOBIANI, A. N.; URSAKI, V. V.; RADAUTSAN, S. I.; TIGINYANU, I. M. (ELSEVIER, 1985)
    Results of a study of near-band-edge absorption in both initial and annealed CdGa2S4 and CdIn2S4 single crystals at different temperatures are presented. Exciton-phonon interaction and cation disorder are shown to determine ...
  • Control of HVPE grown GaN nanostruturing by anodization 
    MONAICO, Ed.; MOISE, C.; MIHAI, G.; ENACHESCU, M.; NIELSCH, K.; URSAKI, V. V.; TIGINYANU, I. M. (Institutul de Fizică Aplicată, AŞM, 2018)
    In this paper, results of a systematic study of morphologies obtained with anodization in HNO3, HCl, and NaCl solutions are presented. It is shown that complex pyramidal structures composed by regions with modulated porosity ...
  • Control of persistent photoconductivity in nanostructured InP through morphology design 
    MONAICO, Ed.; POSTOLACHE, V.; BORODIN, E.; URSAKI, V. V.; LUPAN, O.; ADELUNG, R.; NIELSCH, K.; TIGINYANU, I. M. (IOP Publishing Ltd, 2015)
    In this paper, we show that long-duration-photoconductivity decay (LDPCD) and persistent photoconductivity (PPC) in porous InP structures fabricated by anodic etching of bulk substrates can be controlled through the ...
  • Crystal Chemistry of CdIn2S4, MgIn2S4, and MnIn2S4 Thiospinels under High Pressure 
    SANTAMARÍA-PÉREZ, D.; AMBOAGE, M.; MANJÓN, F. J.; ERRANDONEA, D.; MUÑOZ, A.; RODRÍGUEZ-HERNÁNDEZ, P.; MÚJICA, A.; RADESCU, S.; URSAKI, V. V.; TIGINYANU, I. M. (American Chemical Society, 2012)
    We report X-ray diffraction measurements in CdIn2S4, MgIn2S4, and MnIn2S4 thiospinels at room temperature and high pressures. The pressure dependences of the structural parameters have been determined and compared to those ...
  • Design and Characterization of Novel Focusing Elements Based on Photonic Metamaterials 
    TIGINYANU, I. M.; FOCA, E.; SERGENTU, V. V.; URSAKI, V. V.; DASCHNER, F.; KNÖCHEL, R.; FÖLL, H. (American Scientific Publishers, 2009)
    New results in the development of photonic metamaterials based on two dimensional periodic dielectric structures are reported. We show that concave and flat lenses consisting of homogeneous or inhomogeneous dielectric rods ...
  • Design of negative-refractive-index materials on the basis of rods with a gradient of the dielectric constant 
    SERGENTU, V. V.; URSAKI, V. V.; TIGINYANU, I. M.; FOCA, F.; FÖLL, H.; BOYD, Robert W. (American Institute of Physics, 2007)
    The authors propose an approach to the design of negative-refractive-index materials based on the use of dielectric rods with a gradient of the dielectric constant. A triangular-lattice photonic crystal assembled from ...

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