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Browsing Articole ştiinţifice by Author "HARTNAGEL, H. L."

Browsing Articole ştiinţifice by Author "HARTNAGEL, H. L."

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  • 183 GHz Mixer on InGaAs Schottky Diodes 
    OPREA, I.; WALBER, A.; COJOCARI, O.; GIBSON, H.; ZIMMERMANN, R.; HARTNAGEL, H. L. (Oxford, 2010)
    This work reports on experimental results of a 183 GHz sub-harmonically pumped mixer based on InGaAs antiparallel diode pair. The diode structure provides extremely low parasitic capacitance of about 2.5 fF. Roughly estimated ...
  • Broadband power detector using a circularly-toothed planar logarithmic-periodic antenna 
    SYDLO, C.; KÖGEL, B.; COJOCARI, O.; FEIGINOV, M.; HARTNAGEL, H. L.; MEISSNER, P. (IEEE, 2005)
    A broadband antenna has been coupled to a planar Schottky diode for the realisation of a sensitive power detector for mm-wave frequencies. The measured response curve is in agreement with calculations and shows values of ...
  • 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 ...
  • 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 ...
  • DC- and IF-noise performance optimization of GaAs Schottky diodes for THz applications 
    COJOCARI, O.; BIBER, S.; MOTTET, B.; RODRIGUEZ-GIRONES, M.; HARTNAGEL, H. L.; SCHMIDT, L.-P. (IOP Publishing, 2004)
  • 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 ...
  • 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 ...
  • Experimental validation of thermal model of MM-Wave frequency multipliers 
    OPREA, I.; COJOCARI, O.; SOBORNYTSKYY, M.; HARTNAGEL, H. L. (IEEE, 2013)
    This paper presents a method for estimation of junction temperature of a Schottky diode used in a recently developed frequency doubler to 332 GHz. Our particular interest was the validation of the thermal model of the diode ...
  • Fröhlich modes in porous III-V semiconductors 
    SARUA, A.; MONECKE, J.; IRMER, G.; TIGINYANU, I. M.; GÄRTNER, G.; HARTNAGEL, H. L. (IOP Publishing, 2001)
    Porous GaP, InP and GaAs structures fabricated by MeV ion-implantation-assisted electrochemical etching were investigated by Raman and Fourier transform infrared spectroscopy. Fröhlich modes in the frequency gap between ...
  • GaN Schottky multiplier diodes prepared by electroplating: a study of passivation technology 
    COJOCARI, O.; POPA, V.; URSAKI, V. V.; TIGINYANU, I. M.; HARTNAGEL, H. L.; DAUMILLER, I. (IOP Publishing, 2004)
    This paper presents the results of a Pt/n-GaN Schottky contact technology development based on electrochemical metal deposition. Three different technological approaches are used to fabricate GaN varactor diodes. The effects ...
  • Heterostructure equivalence of step-recovery diodes for ballistic and diffusive electron resonance - a new concept for THz signal generation 
    HARTNAGEL, H. L.; SCHMIDT, L.-P.; NICOLAE, B.; OPREA, I.; SCHONHERR, D.; ONG, D. S.; SCHUR, J.; RUF, M. (IEEE, 2008)
    A heterostructure equivalent to the well-known step recovery diode principle, arranged as a double structure gives a new nonlinear device for highly efficient harmonic THz signal generation. Like in the case of step recovery ...
  • The impact of process optimization on planar THz-Schottky device reliability 
    MOTTET, B.; SYDLO, C.; KOGEL, B.; ROBILLARD DE, Q.; COJOCARI, O.; HARTNAGEL, H. L. (IEEE, 2004)
    The technological complexity as well as space-application quality standards require sophisticated process control and optimization for reliability improvement of planar THz-Schottky devices. Degradation mechanisms are ...
  • Integration of Ge Nanowire Arrays in Glass Micro-Fibers 
    IOISHER, A.; BADINTER, E.; MONAICO, E.; POSTOLACHE, V.; HARTNAGEL, H. L.; LEPORDA, N.; TIGINYANU, I. (Institute of Applied Physics, Academy of Sciences of Moldova, Chisinau, Republic of Moldova, 2011)
    We report on a technological route for the integration of large arrays of Ge nanowires (NWs) in a human-hair-like glass micro-fiber, the length of the micro-fiber reaching one meter. The route comprises (a) the formation ...
  • Internal quantum efficiency enhancement of InGaN/GaN LEDs with Mg-Si pin-doped GaN quantum barrier 
    KÜPPERS, F.; SIRKELI, V. P.; YILMAZOGLU, O.; AL-DAFFAIE, S.; OPREA, I.; ONG, D. S.; HARTNAGEL, H. L. (Institutul de Fizică Aplicată al AŞM, 2018)
    In this work we study numerically the effect of Mg-Si pindoping of GaN quantum barrier within InGaN/GaN multi quantum wells (MQWs) on the internal quantum efficiency (IQE) of LEDs in comparison with LED devices with undoped, ...
  • Micrometer-size GaN Schottky-diodes for mm-wave frequency multipliers 
    COJOCARI, O.; POPA, V.; URSAKI, V. V.; TIGINYANU, I. M.; MUTAMBA, K.; SAGLAM, M.; HARTNAGEL, H. L. (IEEE, 2004)
    Small-size Pt/n-GaN Schottky diodes are fabricated using electrochemical technique for anode metallisation. Effects of surface passivation and thermal annealing on the interface quality are studied using PL-measurements ...
  • Millimeter-wave receiver based on a folded dipole antenna and Schottky diode for maximum power transfer 
    MONTERO-de-PAZ, J.; UGARTE-MUÑOZ, E.; GARCIA-MUÑOZ, L. E .; SEGOVIA-VARGAS, D.; SCHOENHERR, D.; OPREA, I.; AMRHEIN, A.; COJOCARI, O.; HARTNAGEL, H. L. (IEEE, 2012)
    In this article a millimeter-wave (mm-wave) receiver based on a folded dipole antenna, zero bias Schottky diode and silicon (Si) lens is presented. The antenna is designed in such a way that its input impedance is equal ...
  • A new structural approach for uniform sub-micrometer anode metallization of planar THz Schottky components 
    COJOCARI, O.; MOTTET, B.; RODRIGUEZ-GIRONES, M.; BIBER, S.; MARCHAND, L.; SCHMIDT, L.-P.; HARTNAGEL, H. L. (IOP Publishing, 2004)
    This paper presents the evaluation of a Schottky contact technology based on electrochemical metal deposition. The results of a long-term systematic investigation and optimization of the anode formation process to improve ...
  • A novel system for systematic microwave noise and DC characterization of terahertz Schottky diodes 
    BIBER, S.; COJOCARI, O.; REHM, G.; MOTTET, B.; RODRIGUEZ-GIRONES, M.; SCHMIDT, L.-P.; HARTNAGEL, H. L. (IEEE, 2004)
    An automated system is developed to evaluate a large number Schottky diodes for terahertz applications with respect to their dc and noise characteristics using a highly sensitive noise measurement technique for one port ...
  • Optical mixing in THz Schottky diodes 
    SCHOENHERR, D.; COJOCARI, O.; SYDLO, C.; GOEBEL, T.; FEIGINOV, M.; HARTNAGEL, H. L.; MEISSNER, P. (IEEE, 2008)
    This paper presents the effect of optical mixing in zero-bias InGaAs Schottky detectors at THz frequencies. The excitation of ultrafast carriers by illumination with two 1.5 mum laser beams is verified. This proves the ...
  • Process Control and Failure Analysis Implementation for THz Schottky-based components 
    ICHIZLI, V.; RODRÍGUEZ-GIRONÉS, M.; MARCHAND, L.; GARDEN, C.; COJOCARI, O.; MOTTET, B.; HARTNAGEL, H. L. (Elsevier, 2002)
    Schottky diodes and integrated circuits are most used devices for both frequency mixing and multiplying in THz range. Higher operational frequencies require of the devise dimensions. Devise dimensions in THz range are often ...

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