Browsing Articole ştiinţifice by Author "LANGA, S."

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  • Audio-Transducer for In-Ear-Applications based on CMOS-compatible electrostatic actuators 
    SPITZ, B.; WALL, F.; SCHENK, H.; MELNIKOV, A.; EHRIG, L.; LANGA, S.; STOLZ, M.; KAISER, B.; CONRAD, H.; SCHENK, H. (IEEE, 2019)
    Recently an innovative mSpeaker technology, based on a novel kind of CMOS compatible small gap electrostatic actuators for large deflection, has been introduced. In this paper, we devise methods to model such speakers in ...
  • Cathodoluminescence microanalysis of porous GaP and InP structures 
    TIGINYANU, I. M.; LANGA, S.; SIRBU, L.; MONAICO, E.; STEVENS-KALCEFF, M. A.; FÖLL, H. (EDP Sciences, 2004)
    Electron microscopy and cathodoluminescence (CL) microanalysis were used for a comparative study of porous layers fabricated by electrochemical etching of n-GaP and n-InP substrates in aqueous solutions of sulfuric and ...
  • A comparison of pores in silicon and pores in III–V compound materials 
    CHRISTOPHERSEN, M.; LANGA, S.; CARSTENSEN, J.; TIGINYANU, I. M.; FÖLL, H. (WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim, 2003)
    This paper compares the morphologies of porous silicon and porous III–V compounds and discusses their growth mechanisms. Looking into the fine structure of pores, in silicon (meso)pores with intercalating octahedra are ...
  • 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 ...
  • 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 ...
  • Electrochemical pore etching in Ge – An overview 
    FANG, C.; FÖLL, H.; CARSTENSEN, J.; LANGA, S. (WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim, 2007)
    While electrochemical pore etching in semiconductors has become a thriving field for research (and applications) in the past 15 years or so, little work has been done in Ge. Besides Si, Ge is the only semiconductor with a ...
  • Electrostactically in-plane driven silicon micropump for modular configuration 
    UHLIG, S.; GAUDET, M.; LANGA, S.; SCHIMMANZ, K.; CONRAD, H.; KAISER, B.; SCHENK, H. (University of Twente, 2017)
    We present an in-plane reciprocating displacement micropump for liquids and gases which is actuated by a new class of electrostatic bending actuators capable of deflecting beyond the electrode gap distance. The so called ...
  • Electrostatic bending actuators with a liquid filled nanometer scale gap 
    GAUDET, M.; UHLIG, S.; STOLZ, M.; ARSCOTT, S.; CONRAD, H.; LANGA, S.; KAISER, B.; SCHENK, H. (IEEE, 2017)
    We report a considerable improvement in the electrostatic actuation of silicon-based nano electrostatic drive (NED) structures [1] via the insertion of a liquid into the nanosystem. The dielectric liquid provides an ...
  • Engineering porous III-Vs 
    FÖLL, H.; LANGA, S.; CARSTENSEN, J.; LÖLKES, S.; CHRISTOPHERSEN, M.; TIGINYANU, I. M (ELSEVIER, 2003)
    Porous semiconductors exhibit new and unexpected properties compared to the bulk materials. In III-Vs, many, many new features with respect to optical properties have emerged during the last few years for certain pore ...
  • 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 ...
  • Enhancement of vertical integration density by engineered BSOI wafers 
    KADEN, C.; LANGA, S.; LUDEWIG, T.; SCHÖNBERGER, A.; HERRMANN, A.; GÖBEL, A.; KOLKOVSKY, V.; JEROCH, W.; PUFE, W. (Springer Nature Switzerland, 2018)
    The lateral and vertical integration density of bulk microelectromechanical systems (MEMS) using bonded silicon-on-insulator (BSOI) wafers is significantly enhanced if the handle wafer is used as an electrical redistribution ...
  • Fast pore etching 
    FREY, S.; KEMELL, M.; CARSTENSEN, J.; LANGA, S.; FÖLL, H. (WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim, 2005)
    The growth of silicon macropores under high current densities and high HF concentrations is studied. A new growth mode for porous Si has been found where pores resemble the so-called current line oriented pores previously ...
  • First Time of nanoscopic electrostatic drives pushing for ultrasonic transmission for gesture recognition 
    GUARACAO, J. M. M.; KIRCHER, M.; WALL, F.; KRENKEL, M.; KAISER, B.; LANGA, S.; SCHENK, H. (IEEE, 2020)
    The design, fabrication, and acoustic characterization of an electrostatic ultrasound transducer based on lateral actuation is documented in this letter. Unlike cMUTs or pMUTs, this device-NED-MUT -does not use a membrane ...
  • Focusing effect of photonic crystal concave lenses made from porous dielectrics 
    SERGENTU, V. V.; FOCA, E.; LANGA, S.; CARSTENSEN, J.; FÖLL, H.; TIGINYANU, I. M. (WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim, 2004)
    In the present paper we show the photonic band structure and transmittance spectra of photonic crystal (PC) consisting of porous dielectric and compare the results with the earlier published. Frequency ranges, where PC can ...
  • Formation of Porous Layers with Different Morphologies during Anodic Etching of n-InP 
    LANGA, S.; TIGINYANU, I. M.; CARSTENSEN, J.; CHRISTOPHERSEN, M.; FÖLL, H. (The Electrochemical Society, 1999)
    Two different morphologies of porous layers were observed in (100)-oriented anodically etched in an aqueous solution of . At high current density anodization leads to the formation of so-called current-line oriented ...
  • Formation of Tetrahedron-Like Pores during Anodic Etching of (100) Oriented n-GaAs 
    LANGA, S.; CARSTENSEN, J.; TIGINYANU, I. M.; CHRISTOPHERSEN, M.; FÖLL, H. (The Electrochemical Society, 2002)
    The morphology of porous layers obtained by electrochemical etching of (100) oriented n-GaAs substrates in an aqueous solution of HCl was studied. At low anodic current densities, up to 5 mA/cm2, pores in the form of ...
  • The Impact of Porosity upon the Cathodoluminescence from III-V Compounds 
    STEVENS-KALCEFF, M. A.; TIGINYANU, I. M.; LANGA, S.; FÖLL, H. (Cambridge University Press, 2002)
    The development of applications involving porous materials requires understanding of their special properties. Most published investigations have used photoluminescence (PL) techniques to determine the average emission ...
  • Influence of annealing in H atmosphere on the electrical properties of Al2O3 layers grown on p-type Si by the atomic layer deposition technique 
    KOLKOVSKY, Vl.; STÜBNER, R.; LANGA, S.; WENDE, U.; KAISER, B.; CONRAD, H.; SCHENK, H. (ELSEVIER, 2016)
    In the present study the electrical properties of 100nm and 400nm alumina films grown by the atomic layer deposition technique on p-type Si before and after a post-deposition annealing at 440°C and after a dc H plasma ...
  • Large area etching for porous semiconductors 
    CARSTENSEN, J.; CHRISTOPHERSEN, M.; LÖLKES, S.; OSSEI-WUSU, E.; BAHR, J.; LANGA, S.; POPKIROV, G.; FÖLL, H. (WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim, 2005)
    While electrochemical etching of small samples in the 1 cm region is relatively easy, this is not true for large areas, i.e. standard wafer sizes up to 300 mm. The paper outlines the specific demands and difficulties in ...
  • Luminescence of GaN nanocolumns obtained by photon-assisted anodic etching 
    TIGINYANU, I. M.; URSAKI, V. V.; ZALAMAI, V. V.; LANGA, S.; HUBBARD, S.; PAVLIDIS, D.; FÖLL, H. (American Institute of Physics, 2003)
    GaN nanocolumns with transverse dimensions of about 50 nm were obtained by illumination-assisted anodic etching of epilayers grown by metalorganic chemical vapor deposition on sapphire substrates. The photoluminescence ...

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