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Browsing Articole din publicaţii internaţionale by Author "TIGINYANU, I. M."

Browsing Articole din publicaţii internaţionale by Author "TIGINYANU, I. M."

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  • 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 ...
  • Correlation between morphology and cathodoluminescence in porous GaP 
    STEVENS-KALCEFF, M. A.; TIGINYANU, I. M.; LANGA, S.; FÖLL, H.; HARTNAGEL, H. L. (American Institute of Physics, 2001)
    Porous layers fabricated by anodic etching of n-GaPn-GaP substrates in a sulfuric acid solution were studied by electron microscopy and cathodoluminescence (CL) microanalysis. The morphology of porous layers was found to ...
  • 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 ...
  • “Dark” modes backscattering as possible rationale for anomalous retroreflection from strongly absorbing porous nanostructures 
    SERGENTU, V. V.; URSAKI, V.; MONAICO, Ed.; TIGINYANU, I. M.; PRISLOPSKI, S. Ya.; GAPONENKO, S. V. (World Scientific, 2017)
    The previously discovered anomalous retroreflection in a strongly absorbing nanostructured medium is explained by using “dark” and “bright” modes. The consideration provides rationale not only for the retroreflection itself ...
  • 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 and maskless fabrication of ultrathin suspended membranes of GaN 
    TIGINYANU, I. M.; POPA, V.; STEVENS-KALCEFF, M. A.; GERTHSEN, D.; BRENNER, P.; PAVLIDIS, D. (WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim, 2012)
    We report the maskless fabrication of ultrathin suspended GaN membranes designed by focused ion beam treatment of the GaN epilayer surface with subsequent photoelectrochemical etching. This technological approach allows ...
  • 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 ...
  • Design of New Nonlinear Optical Materials Based on Porous III–V Compounds 
    TIGINYANU, I. M.; KRAVETSKY, I. V.; MAROWSKY, G.; MONECKE, J.; HARTNAGEL, H. L. (John Wiley & Sons, Inc, 2000)
    Bulk and porous membranes of gallium phosphide have been characterized by optical second harmonic generation (SHG) technique using a 1064 nm pump beam. The porous membranes prove to exhibit an enhanced SHG in comparison ...
  • Design of trapped surface charge for the photoelectrochemical fabrication of GaN mesostructures 
    POPA, V.; VOLCIUC, O.; TIGINYANU, I. M. (WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim, 2004)
    In this note we demonstrate that artificially introduced surface defects in GaN epilayers are stable against photoelectrochemical etching in aqueous solution of KOH. The origin of this stability is attributed to the negative ...
  • Effect of heavy noble gas ion irradiation on terahertz emission efficiency of InP (100) and (111) crystal planes 
    RADHANPURA, K.; LEWIS, R. A.; SIRBU, L.; ENACHI, M.; TIGINYANU, I. M.; SKURATOV, V. A. (IOP Publishing, 2014)
    Emission of terahertz (THz) electromagnetic radiation from heavily-doped (5 × 1018 cm−3) (100) and (111) InP bulk materials and nanoporous honeycomb membranes, irradiated with heavy noble gas (Kr and Xe) ions, is presented. ...
  • Effects of morphology on the emission of photons from GaN membranes fabricated using surface charge lithography 
    STEVENS-KALCEFF, M. A.; TIGINYANU, I. M.; POPA, V.; BRANISTE, T.; BRENNER, P. (Society of Photo-Optical Instrumentation Engineers, SPIE, 2013)
    Cathodoluminescence (CL) microanalysis has been used to investigate ultra-thin suspended GaN membranes fabricated from GaN epilayer surfaces by focused ion beam (FIB) pre-treatment and subsequent photoelectrochemical (PEC) ...
  • Effects of the Cations on the Raman Spectra of Sulphur Defect Chalcopyrites 
    TIGINYANU, I. M.; LOTTICI, P. P.; RAZZETTI, C.; GENNARI, S. (IOP Publishing, 1993)
    We report the Raman spectrum of defect chalcopyrite compounds CdAl2S4, CdGa2S4, ZnGa2S4 and of the isostructural mixed compounds Zn0.7Cd0.3Al2S4, ZnGa0.2Al1.8S4 and ZnGa0.8Al1.2S4. The role of the cations on the vibrational ...
  • Efficient focusing with a concave lens based on a photonic crystal with an unusual effective index of refraction 
    FOCA, E.; FÖLL, H.; DASCHNER, F.; SERGENTU, V. V.; CARSTENSEN, J.; FREY, S.; KNÖCHEL, R.; TIGINYANU, I. M. (WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim, 2005)
    This work reports measurements with a concave lens based on a photonic crystal (PC) structure, which was designed to have an effective index of refraction neff < 1 or even < 0, and which is intended as a model system for ...
  • Electrical characterization and cathodoluminescence microanalysis of AlN/GaN heterostructures 
    HUBBARD, S. M.; PAVLIDIS, D.; VALIAEV, V.; STEVENS-KALCEFF, M. A.; TIGINYANU, I. M. (ELSEVIER, 2002)
    Low-pressure MOCVD is used to grow AlN/GaN MIS-type heterostructures with AlN thickness between 3 and 35 nm. The two-dimensional electron gas (2DEG) Hall mobility was found to decrease with AlN thickness. The measured room ...
  • Electrochemical Deposition by Design of Metal Nanostructures 
    MONAICO, Ed.; MONAICO, E. I.; URSAKI, V. V.; TIGINYANU, I. M.; NIELSCH, K. (Springer Nature Switzerland, 2019)
    We report on the application of specially-designed masks for the purpose of electrochemical etching of InP single crystals which enables one to change in a controlled fashion the direction of propagation of pores, including ...
  • Electrochemical nanostructuring 
    TIGINYANU, I. M. (Institutul de Fizică Aplicată al AŞM, 2012)
    The work represents a review of technological approaches for 2D and 3D nanostructuring of semiconductor compounds by using radiation treatment and electrochemistry. Novel spatial nanoarchitectures based on III-V and II-VI ...
  • Electrochemical pore etching in Ge 
    LANGA, S.; CHRISTOPHERSEN, M.; CARSTENSEN, J.; TIGINYANU, I. M.; FÖLL, H. (WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim, 2003)
    Nucleation and growth of electrochemically obtained pores on (111) and (100) oriented n-Ge in different electrolytes was investigated. On rough surfaces pore density increases as the current density increases, whereas on ...
  • Electron field emission from narrow band gap semiconductors InAs 
    LITOVCHENKO, V.; EVTUKH, A.; SEMENENKO, M.; GRYGORIEV, A.; YILMAZOGLU, O.; HARTNAGEL, H. L.; SIRBU, L.; TIGINYANU, I. M.; URSAKI, V. V. (IOP Publishing, 2007)
    We propose to use InAs for the development of effective electron field emitters on the basis of a new technological approach for the preparation of highly textured surfaces which allows one to obtain peculiar fine rod-like ...
  • Engineering the morphology of porous InP for waveguide applications 
    LANGA, S.; LÖLKES, S.; CARSTENSEN, J.; HERMANN, M.; BÖTTGER, G.; TIGINYANU, I. M.; FÖLL, H. (WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim, 2005)
    We research the possibilities for engineering the morphology of porous structures in n-InP. Lithographic patterning of the sample surface before anodic etching is shown to modify considerably the electric field distribution ...
  • Enhanced radiation hardness of ZnO nanorods versus bulk layers 
    BURLACU, A.; URSAKI, V. V.; LINCOT, D.; SKURATOV, V. A.; PAUPORTE, T.; RUSU, E.; TIGINYANU, I. M. (WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim, 2008)
    It is shown that ZnO nanorods grown by MOCVD exhibit enhanced radiation hardness against high energy heavy ion irradiation as compared to bulk layers. The decrease of the luminescence intensity induced by 130 MeV Xe+23 ...

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