Articole ştiinţifice: Recent submissions

  • Ultrafast third-order optical nonlinearity in SnS2 layered compound for photonic applications 
    PETRIS, Adrian; GHEORGHE, Petronela S.; VLAD, Valentin I.; RUSU, Emil; URSAKI, Veaceslav V.; TIGINYANU, Ion M. (ELSEVIER, 2018)
    The ultrafast nonlinear optical response of SnS2 layered compound, excited by high-repetition-rate ultrashort (fs) pulses at 1550 nm wavelength, is investigated for the first time by optical third harmonic generation. In ...
  • 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. ...
  • 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 ...
  • Superlensing with plane plates consisting of dielectric cylinders in glass envelopes 
    FOCA, E.; SERGENTU, V. V.; DASCHNER, F.; TIGINYNAU, I. M.; URSAKI, V. V.; KNÖCHEL, R.; FÖLL, H. (WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim, 2009)
    The approach of designing negative-refractive-index materials on the basis of dielectric rods with a gradient of the dielectric constant is tested experimentally. A triangular-lattice plane-parallel slab assembled from ...
  • Filiform Nanostructure Technologies Based on Microwire Stretching 
    IOISHER, A. M.; BADINTER, E. Ya.; POSTOLACHE, V.; MONAICO, E. V.; URSAKI, V. V.; SERGENTU, V. V.; TIGINYANU, I. M. (American Scientific Publishers, 2012)
    A technological route allowing one to integrate huge amounts of electrically isolated metal, semiconductor, or semimetal nanowires in glass fibers with the diameter of up to a few hundreds of micrometers is presented, and ...
  • Cathodoluminescence characterization of suspended GaN nanomembranes 
    STEVENS-KALCEFF, M. A.; TIGINYANU, I. M.; POPA, V.; BRANISTE, T.; BRENNER, P. (AIP Publishing LLC, 2013)
    Continuous suspended ~15 nm thick gallium nitride (GaN) nano-membranes have been investigated using cathodoluminescence microanalysis. The GaN nanomembranes are fabricated by focused ion beam (FIB) pre-treatment of GaN ...
  • 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. ...
  • 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 ...
  • 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 ...
  • Atomically thin semiconducting layers and nanomembranes: a review 
    DRAGOMAN, Mircea; DRAGOMAN, Daniela; TIGINYANU, Ion (IOP Publishing, 2017)
    This article reviews the main physical properties of atomically thin semiconductors and the electronic devices based on them. We start with graphene, describing its physical properties and growth methods, followed by a ...
  • Focusing slabs made of negative index materials based on inhomogeneous dielectric rods 
    SERGENTU, V. V.; URSAKI, V. V.; TIGINYANU, I. M.; FOCA, E.; FÖLL, H.; BOYD, Robert W. (WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim, 2006)
    We show the advantages of using inhomogeneous dielectric rods to design photonic crystals that behave as materials with negative refractive index. We found that the analysis of light scattering properties of inhomogeneous ...
  • Cathodoluminescence microscopy and spectroscopy of GaN epilayers microstructured using surface charge lithography 
    DÍAZ-GUERRA, C.; PIQUERAS, J.; VOLCIUC, O.; POPA, V.; TIGINYANU, I. M. (American Institute of Physics, 2006)
    Cathodoluminescence (CL) microscopy and spectroscopy have been used to investigate the optical properties of GaN microstructures patterned by Ar+ ion irradiation and subsequent photoelectrochemical (PEC) etching. Monochromatic ...
  • Porous II-VI vs. porous III-V semiconductors 
    LANGA, S.; TIGINYANU, I. M.; MONAICO, E.; FÖLL, H. (WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim, 2011)
    In this work a morphological comparison of porous structures obtained by means of electrochemical etching in II-VI (ZnSe, CdSe) and III-V (InP, GaAs, GaP) semiconductors is presented. It is shown that in III-V semiconductors ...
  • Photoinduced modification of surface states in nanoporous InP 
    LLOYD-HUGHES, J.; MÜLLER, S.; SCALARI, G.; BISHOP, H.; CROSSLEY, A.; ENACHI, M.; SIRBU, L.; TIGINYANU, I. M. (American Institute of Physics, 2012)
    Porous honeycombs of n-type InP were investigated by terahertz time-domain and x-ray photoemission spectroscopies. After photoexcitation the dark conductivity was found to increase quasi-irreversibly, recovering only after ...
  • Two-Dimensional Metallo-Semiconductor Networks for Electronic and Photonic Applications 
    TIGINYANU, Ion; MONAICO, Eduard; URSAKI, Veaceslav (The Electrochemical Society, 2019)
    Two-dimensional metallo-semiconductor networks have been fabricated by pulsed electrochemical deposition of Pt inside porous GaP membranes with parallel pores possessing diameters in the micrometer and sub-micrometer ranges. ...
  • 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 ...
  • Nucleation and growth of macro pores on (100) n-type Ge 
    LANGA, S.; CARSTENSEN, J.; TIGINYANU, I. M.; FÖLL, H. (WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim, 2005)
    The authors investigate the nucleation and growth of macro pores on n-type Ge in the dark and with back side illumination. We show that nucleation on Ge is strongly dependent on the surface defect structure and therefore ...
  • 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 ...
  • Yellow Luminescence and Optical Quenching of Photoconductivity in Ultrathin Suspended GaN Membranes Produced by Surface Charge Lithography 
    POPA, V.; BRANISTE, T.; STEVENS-KALCEFF, M. A.; GERTHSEN, D.; BRENNER, P.; POSTOLACHE, V.; URSAKI, V.; TIGINYANU, I. M. (American Scientific Publishers, 2013)
    Spatial and spectral distribution of cathodoluminescence as well as photoelectrical properties under excitation with two beams of monochromatic radiation of various wavelengths are investigated in ultrathin suspended GaN ...
  • Retroreflection of light from nanoporous InP: correlation with high absorption 
    PRISLOPSKI, S. Ya.; TIGINYANU, I. M.; GHIMPU, L.; MONAICO, E.; SIRBU, L.; GAPONENKO, S. V. (Springer Nature Switzerland, 2014)
    Pronounced retroreflection behavior is reported for a fishnet nanoporous strongly absorbing semiconductor material. Retroreflection appears along with diffusive specular reflection for all angles of incidence for light ...

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