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Browsing Articole ştiinţifice by Author "URSAKI, Veaceslav"

Browsing Articole ştiinţifice by Author "URSAKI, Veaceslav"

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  • Birefringence, isotropic points, and optical filters based on CuAl/sub x/Ga/sub 1- x/Se(S)/sub 2/ crystals 
    MAȘNIC, Alisa; URSAKI, Veaceslav (Institutul de Inginerie Electronică şi Nanotehnologii "D. Ghiţu", 2021)
    A brief review on birefringence and optical filters based on CuAl/sub x/Ga/sub 1- x/Se(S)/sub 2/ crystals is given in this paper. Two types of isotropic points are analyzed; one of them refers to a case when the wavelength ...
  • Body zero frequency modes in photonic crystals of nanopores and nanocylinders 
    SERGENTU, Vladimir; URSAKI, Veaceslav; SIRBU, Lilian (WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim, 2013)
    In this paper, we demonstrate that body zero frequency modes can exist at extremely low frequencies in a system of nanocylinders made of non-dissipative material. Such kind of modes is not specific to single nanocylinders, ...
  • Cathodoluminescence of TiO2 nanotubes prepared by low-temperature anodization of Ti foils 
    ENACHI, Mihai; STEVENS-KALCEFF, Marion; TIGINYANU, Ion; URSAKI, Veaceslav (ELSEVIER, 2010)
    We show that anodization of Ti sheets in an ethylene glycol and HF containing electrolyte at temperatures under 0°C results in the formation of a self-arranged ordered porous structure at the top surface of the sample. ...
  • Design of titania nanotube structures by focused laser beam direct writing 
    ENACHI, Mihai; STEVENS-KALCEFF, Marion A.; SARUA, Andrei; URSAKI, Veaceslav; TIGINYANU, Ion (AIP Publishing LLC, 2013)
    In this work, we report on electrochemical fabrication of titania films consisting of nanotubes (NTs) and their treatment by focused laser beam. The results of sample characterization by optical and scanning electron ...
  • Design of titania nanotube structures by focused laser beam writing 
    ENACHI, Mihai; SARUA, Andrei; STEVENS-KALCEFF, Marion; TIGINYANU, Ion; GHIMPU, Lidia; URSAKI, Veaceslav (IEEE, 2013)
    Matrices of titania nanotubes (TiO 2 NTs) have been prepared by anodization of Ti foils in ethylene glycol based electrolyte. These matrices were subjected to annealing at various temperatures or exposed to a focused laser ...
  • Fabrication of photonic crystal circuits based on GaN ultrathin membranes by maskless lithography 
    VOLCIUC, Olesea; BRANISTE, Tudor; SERGENTU, Vladimir; URSAKI, Veaceslav; TIGINYANU, Ion M.; GUTOWSKI, Jürgen (Society of Photo-Optical Instrumentation Engineers, SPIE, 2015)
    We report on maskless fabrication of photonic crystal (PhC) circuits based on ultrathin (d~15 nm) nanoperforated GaN membranes exhibiting a triangular lattice arrangement of holes with diameters of 150 nm. Ultrathin GaN ...
  • Flexible pressure sensor based on graphene aerogel microstructures functionalized with CdS nanocrystalline thin film 
    PLESCO, Irina; DRAGOMAN, Mircea; STROBEL, Julian; GHIMPU, Lidia; SCHÜTT, Fabian; DINESCU, Adrian; URSAKI, Veaceslav; KIENLE, Lorenz; ADELUNG, Rainer; TIGINYANU, Ion (ELSEVIER, 2018)
    In this paper, we report on functionalization of graphene aerogel with a CdS thin film deposited by magnetron sputtering and on the development of flexible pressure sensors based on ultra-lightweight CdS-aerogel nanocomposite. ...
  • GaN nanostructuring for the fabrication of thin membranes and emerging applications 
    TIGINYANU, Ion; URSAKI, Veaceslav (TUBITAK, 2014)
    We present a review of technological methods developed in recent years for the purpose of gallium nitride nanostructuring, with the main focus on fabrication of thin GaN membranes. In particular, we report on traditional ...
  • Hierarchical Aerographite 3D flexible networks hybridized by InP micro/nanostructures for strain sensor applications 
    PLESCO, Irina; STROBEL, Julian; SCHÜTT, Fabian; HIMCINSCHI, Cameliu; BEN SEDRINE, Nabiha; MONTEIRO, Teresa; CORREIA, Maria Rosário; GORCEAC, Leonid; CINIC, Boris; URSAKI, Veaceslav; MARX, Janik; FIEDLER, Bodo; MISHRA, Yogendra Kumar; KIENLE, Lorenz; ADELUNG, Rainer; TIGINYANU, Ion (Springer Nature Limited, 2018)
    In the present work, we report on development of three-dimensional flexible architectures consisting of an extremely porous three-dimensional Aerographite (AG) backbone decorated by InP micro/nanocrystallites grown by a ...
  • Highly Porous and Ultra-Lightweight Aero-Ga2O3: Enhancement of Photocatalytic Activity by Noble Metals 
    PLESCO, Irina; CIOBANU, Vladimir; BRANISTE, Tudor; URSAKI, Veaceslav; RASCH, Florian; SARUA, Andrei; RAEVSCHI, Simion; ADELUNG, Rainer; DUTTA, Joydeep; TIGINYANU, Ion (MDPI, 2021)
    A new type of photocatalyst is proposed on the basis of aero-β-Ga2O3, which is a material constructed from a network of interconnected tetrapods with arms in the form of microtubes with nanometric walls. The aero-Ga2O3 ...
  • The impact of nanoperforation on persistent photoconductivity and optical quenching effects in suspended GaN nanomembranes 
    VOLCIUC, Olesea; BRANISTE, Tudor; TIGINYANU, Ion; STEVENS-KALCEFF, Marion A.; EBELING, Jakob; ASCHENBRENNER, Timo; HOMMEL, Detlef; URSAKI, Veaceslav; GUTOWSKI, Jürgen (AIP Publishing LLC, 2013)
    We report on fabrication of suspended ~15 nm thick GaN membranes nanoperforated in an ordered fashion using direct writing of negative charges by focused ion beam and subsequent photoelectrochemical etching of GaN epilayers. ...
  • Metallized Porous GaP Templates for Electronic and Photonic Applications 
    TIGINYANU, Ion; MONAICO, Eduard; SERGENTU, Vladimir; TIRON, Andrei; URSAKI, Veaceslav (IOP Publishing, 2014)
    We report on fabrication of two-dimensional metallo-semiconductor networks by using pulsed electroplating of Pt inside electrochemically-prepared porous GaP layers with parallel pores possessing diameters in the micrometer ...
  • Modulation of Electrical Conductivity and Lattice Distortions in Bulk HVPE-Grown GaN 
    WOLFF, Niklas; JORDT, Philipp; BRANISTE, Tudor; POPA, Veaceslav; MONAICO, Eduard; URSAKI, Veaceslav; PETRARU, Adrian; ADELUNG, Rainer; MURPHY, Bridget M.; KIENLE, Lorenz; TIGINYANU, Ion (The Electrochemical Society, 2019)
    The nature of self-organized three-dimensional structured architectures with spatially modulated electrical conductivity emerging in the process of hydride vapor phase epitaxial growth of single crystalline n-GaN wafers ...
  • Nearfield effect in a nanotube/nanopor array system for application in EWOD devices that are operating in THz region 
    SIRBU, Lilian; SERGENTU, Vladimir; VOICU, Rodica; TIGINYANU, Ion; URSAKI, Veaceslav (IEEE, 2012)
    We present a theoretical model for propagation of EM wav. in various kinds of structures such as arrays of monolayer cylinders, multilayer cylinders, non-metallized and metallised pores. An analytical method was developed ...
  • Photocatalytic properties of TiO2 nanotubes doped with Ag, Au and Pt or covered by Ag, Au and Pt nanodots 
    ENACHI, Mihail; GUIX, Maria; BRANISTE, Tudor; POSTOLACHE, Vitalie; CIOBANU, Vladimir; URSAKI, Veaceslav; SCHMIDT, Oliver G.; TIGINYANU, Ion (Springer Nature Switzerland, 2015)
    Titania nanotube arrays have been prepared by anodic oxidation of titanium foils in an electrolyte solution containing a mixture of hydrofluoric acid, ethylene glycol, and phosphoric acid. The initially amorphous nanotubes ...
  • Photonic Crystal Structures Based on GaN Ultrathin Membranes 
    VOLCIUC, Olesea; SERGENTU, Vladimir; TIGINYANU, Ion; SCHOWALTER, Marco; URSAKI, Veaceslav; ROSENAUER, Andreas; HOMMEL, Detlef; GUTOWSKI, Jürgen (American Scientific Publishers, 2014)
    We report on maskless fabrication of ultrathin (d ~ 15 nm) nanoperforated GaN membranes exhibiting a triangular lattice arrangement of holes with a diameter of 150 nm, and show that these membranes represent an intermediate ...
  • Porous semiconductor compounds 
    MONAICO, Eduard; TIGINYANU, Ion; URSAKI, Veaceslav (IOP Publishing, 2020)
    In this review paper, we present a comparative analysis of the electrochemical dissolution of III–V (InP, GaAs, GaN), II–VI (ZnSe, CdSe) and SiC semiconductor compounds. The resulting morphologies are discussed, including ...
  • Preparation of poly(N-vinylpyrrolidone)-stabilized ZnO colloid nanoparticles 
    GUTUL, Tatyana; RUSU, Emil; CONDUR, Nadejda; URSAKI, Veaceslav; GONCEARENCO, Evgenii; VLAZAN, Paulina (Beilstein Institute for the Advancement of Chemical Sciences, Germany, 2014)
    We propose a method for the synthesis of a colloidal ZnO solution with poly(N-vinylpyrrolidone) (PVP) as stabilizer. Stable colloidal solutions with good luminescence properties are obtained by using PVP as stabilizer in ...
  • Self-organized nucleation layer for the formation of ordered arrays of double-walled TiO2 nanotubes with temperature controlled inner diameter 
    ENACHI, Mihai; TIGINYANU, Ion; SPRINCEAN, Veaceslav; URSAKI, Veaceslav (WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim, 2010)
    Abstract It is proposed to use the variation of the electrolyte temperature to fabricate titania nanotubes with variable inner diameter at a constant outer diameter and an invariable package density. The anodization of Ti ...
  • Strong light scattering and broadband (UV to IR) photoabsorption in stretchable 3D hybrid architectures based on aerographite decorated by ZnO nanocrystallites 
    TIGINYANU, Ion; GHIMPU, Lidia; GRÖTTRUP, Jorit; POSTOLACHE, Vitalie; MECKLENBURG, Matthias; STEVENS-KALCEFF, Marion A.; URSAKI, Veaceslav; PAYAMI, Nader; FEIDENHANSL, Robert; SCHULTE, Karl; ADELUNG, Rainer; MISHRA, Yogendra Kumar (Springer Nature, 2016)
    In present work, the nano- and microscale tetrapods from zinc oxide were integrated on the surface of Aerographite material (as backbone) in carbon-metal oxide hybrid hierarchical network via a simple and single step ...

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