Papers by Author: Thomas Stauden

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Authors: Jörg Pezoldt, Thomas Kups, Petia Weih, Thomas Stauden, Oliver Ambacher
Abstract: 3C-(Si1-xC1-y)Gex+y ternary alloys were grown on 8.5° off axis 4H-SiC substrates by solid source molecular beam epitaxy in a temperature range between 750°C and 950°C. Energy dispersive X-ray (EDX) analysis revealed a decrease of the Ge incorporation versus substrate temperature. This effect is due to the fixed Si/Ge ratio during the epitaxial growth. The Ge distribution within the grown epitaxial layers was found to be nearly homogeneous. The investigations by atomic location by channeling enhanced microanalysis allowed the conclusion that Ge is located mainly at Si lattice sites.
Authors: Jörg Pezoldt, Bernd Schröter, Volker Cimalla, Thomas Stauden, R. Goldhahn, Henry Romanus, Lothar Spieß
Authors: Johannes Reiprich, Thomas Stauden, Theresa Berthold, Marcel Himmerlich, Jörg Pezoldt, Heiko O. Jacobs
Abstract: Gallium oxide nanowires were grown on different substrates using a corona plasma assisted vapor phase epitaxy process and gold catalyst. It is shown that the silicon carbide pseudo substrate in combination with the plasma excitation of the gas phase supports the growth of the gallium oxide nanowires. Analyzing the orientation of the nanowires with respect to the growth surface, it is concluded that the nanowires growth proceed along the fast growth direction of gallium oxide.
Authors: Lars Hiller, Thomas Stauden, Ricarda M. Kemper, Jörg K.N. Lindner, Donat J. As, Jörg Pezoldt
Abstract: Anisotropic etching processes for mesa structure formation using fluorinated plasma atmospheres in an electron cyclotron resonance (ECR) plasma etcher were studied on Novasic substrates with 10 µm thick 3C-SiC(100) grown on Si(100). To achieve reasonable etching rates, a special gas inlet system suitable for injecting SF6 into the high density downstream Ar ECR plasma was designed. The influence of the etching mask material on the sidewall morphology was investigated. Masking materials with small grain sizes are preferable to achieve a desired shape. The evolution of the mesa form was investigated in dependence on the gas composition, the applied bias, the pressure and the composition of the gas atmosphere. The achieved sidewall slope was 84.5 deg. The aspect ratios of the fabricated structures in the developed residue free ECR plasma etching process were between 5 and 10. Mesa structures aligned to [100] and [110] directions were fabricated.
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, Henry Romanus, Thomas Stauden, Lothar Spieß, Oliver Ambacher, Jörg Pezoldt
Abstract: In the present work cubic 3C-(Si1-xC1-y)Gex+y solid solutions were grown at different^temperatures by molecular beam epitaxy on on-axis 4H-SiC (0001) substrates. Two different growth methods are compared in order to explore the optimal growth conditions for the incorporation of Ge into the SiC lattice during the low temperature epitaxy. For this reason simultaneous growth and migration enhanced epitaxy were used. The chemical composition of the grown layers were analyzed by energy dispersive x-ray methods during transmission electron microscopy investigations. It was found that the migration enhanced epitaxy is a more suitable technique for the formation of high quality (Si1-xC1-y)Gex+y solid solutions. Additionally, polytypes transition from 4H-SiC to 3C-SiC occurs during the growth independent of the applied growth technique.
Authors: Jörg Pezoldt, Thomas Stauden, Volker Cimalla, Gernot Ecke, Henry Romanus, G. Eichhorn
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: Lars Hiller, Thomas Stauden, Ricarda M. Kemper, Jörg K.N. Lindner, Donat J. As, Jörg Pezoldt
Abstract: An anisotropic etching process for mesa structures using fluorinated plasma with hydrogen addition was developed in an electon cyclotron resonance setup. The evolution of the mesa morphology was studied in dependence on the gas composition, the applied bias and the pressure. The achieved side wall slope approached 90° with a negligible trenching. The aspect ratios of the fabricated structure in the developed residue free ECR plasma etching process were between 5 and 20.
Authors: Gabriel Ferro, Maher Soueidan, Christophe Jacquier, Phillippe Godignon, Thomas Stauden, Jörg Pezoldt, Mihai Lazar, Josep Montserrat, Yves Monteil
Abstract: Al-Si and Ge-Si systems were studied for selective epitaxial growth (SEG) of 4H-SiC by the Vapour-Liquid-Solid mechanism. Al-Si and Ge-Si bilayers stackings were deposited on 8° off, Si face, 4H-SiC substrates. After patterning of the layers, the samples were heated up to 1000°C and 1220°C, respectively, for Al-Si and Ge-Si stackings in order to melt the layers. Propane was introduced either during the initial heating ramp, before melting of the alloy, or after reaching the temperature plateau. It was found that introduction of propane before melting was a key parameter in order to improve the homogeneity of the deposit. In both cases, SEG of SiC was achieved. However, the best results were obtained with Ge-Si system giving smooth and uniform ∼100 nm thick epitaxial deposits on all the pattern sizes and shapes. Ge incorporation in the SiC was found to be rather limited but homogeneous in the layer.
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