Papers by Author: Christian Förster

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Authors: Ariadne Andreadou, Jörg Pezoldt, Christian Förster, Efstathios K. Polychroniadis, M. Voelskow, Wolfgang Skorupa
Abstract: One of the main challenging tasks in the prospective technology is the buckling suppression of the 3C-SiC film due to the melting and solidification process and the stress relief as a consequence of the short time Si melting during the Flash Lamp Annealing. To overcome this effect and to stabilize a flat surface morphology an alternative i-FlASiC process was developed. This work refers to the influence of the layer stack modifications by doping and meltstop formation by ion implantation on the wafer buckling. The samples were studied by transmission electron microscopy, high resolution x-ray diffraction and infrared ellipsometry. The aim was to optimize the doping and flash lamp annealing conditions in relation to the i-FLASiC layer stack modification.
Authors: Christian Förster, Pierre M. Masri, Jörg Pezoldt
Authors: Christian Förster, Volker Cimalla, Ratislav Kosiba, Gernot Ecke, Petia Weih, Oliver Ambacher, Jörg Pezoldt
Authors: Jörg Pezoldt, Christian Förster, Volker Cimalla, Florentina Will, Ralf Stephan, Klemens Brueckner, Matthias A. Hein, Oliver Ambacher
Abstract: The resonant frequencies and quality factors of MEMS and NEMS depend critically on the layer quality and the residual stress in the SiC/Si heterostructure. It is demonstrated, that FTIRellipsometry is a suitable technique for monitoring the inhomogeneous residual stress inside SiC/Si heterostructures containing thin layers and their variation with during processing.
Authors: Jörg Pezoldt, Francisco M. Morales, Thomas Stauden, Christian Förster, Efstathios K. Polychroniadis, J. Stoemenos, D. Panknin, Wolfgang Skorupa
Abstract: Flash lamp annealing of multilayer stack of the type SiC/Silicon overlayer(SOL)/SiC reduces the defect densities in the 3C-SiC/Si heteroepitaxial structure. Ge and C additions to the SOL lead to a substantial increase of the mass transfer from the upper layer to the lower SiC layer. If the Ge content of the SOL and the flash lamp annealing conditions are properly chosen a homogeneous layer with a 3C-SiC thickness between 150 and 200 nm can be achieved corresponding to a growth rate between 7.5 and 10.0 +m/s. The thickening of the lower layer depends on the SOL composition. Ge and/or C incorporation into the SOL and therefore into the Si melt enhances the mass transport from the upper SiC layer to the lower one.
Authors: Petia Weih, Volker Cimalla, Christian Förster, Jörg Pezoldt, Thomas Stauden, Lothar Spieß, Henry Romanus, M. Eickhoff, M. Hermann, Pierre M. Masri, Oliver Ambacher
Authors: Carsten Rockstuhl, H.P. Herzig, Christian Förster, André Leycuras, Oliver Ambacher, Jörg Pezoldt
Abstract: The fabrication process and the spectral properties of gratings for the infrared wavelength region on the basis of 3C-SiC layers grown by CVD on (100) oriented Si substrates are demonstrated. The formed 3C-SiC gratings on Si support two phonon polaritons as a function of the geometrical properties excited between 10.3 and 11.4 µm. They appear as a dip in the transmission spectrum. A third minimum in the transmission spectrum is caused by the substrate – grating interaction. The obtained resonances were polarization sensitive, i.e. they appeared only under TMpolarized illumination.
Authors: Christian Förster, Ratislav Kosiba, Gernot Ecke, Volker Cimalla, Oliver Ambacher, Jörg Pezoldt
Abstract: The effects of argon and nitrogen bombardment of 3C-SiC surfaces at acceleration voltages below 2 keV were studied by stylus profilometry, reflectometry, reflection high energy electron diffraction and Auger electron spectroscopy (AES). The erosion rate of the SiC surface was determined. It was found that the sputtering rate for argon was three times higher compared to nitrogen. AES measurements revealed argon and nitrogen incorporation at a depth of a few nanometers as well as stoichiometric changes at the same depth scale independent of the acceleration voltage. In the case of the interaction of nitrogen ions with the 3C-SiC surface the formation of a SiCNalloy was detected.
Authors: Christian Förster, Volker Cimalla, Oliver Ambacher, Jörg Pezoldt
Abstract: In the present work an UHVCVD method was developed which allows the epitaxial growth of 3C-SiC on Si substrates at temperatures below 1000°C. The developed method enable the growth of low stress or nearly stress free single crystalline 3C-SiC layers on Si. The influence of hydrogen on the growth process are be discussed. The structural properties of the 3C-SiC(100) layers were studied with reflection high-energy diffraction, atomic force microscopy, X-ray diffraction and the layer thickness were measured by reflectometry as well as visible ellipsometry. The tensile strain reduction at optimized growth temperature, Si/C ratio in the gas phase and deposition rate are demonstrated by the observation of freestanding SiC cantilevers.
Authors: Christian Förster, Volker Cimalla, M. Stubenrauch, Carsten Rockstuhl, Klemens Brueckner, Matthias A. Hein, Jörg Pezoldt, Oliver Ambacher
Abstract: In this paper the multifariousness of SiC/Si heterostructures for device and sensor applications will be demonstrated. 3C-SiC based microelectromechanical resonator beams (MEMS) with different geometries actuated by the magnetomotive effect operating under ambient conditions were fabricated. The resonant frequency reaches values up to 2 MHz. The applications of these resonators are the measurement of the viscosity of liquids or mass detection. Furthermore, photonic devices in the form of SiC/Si infrared gratings for wavelength and polarization filters in infrared spectra are processed. SiC wear protection for a dosing system with the possibility to dose nano- or picoliter droplets of water based liquids as well as SiC nanomasking for catalytic agent nanostructures are demonstrated.
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