Papers by Author: Wolfgang J. Choyke

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Authors: Peter Deák, Adam Gali, Z. Hajnal, Thomas Frauenheim, Nguyen Tien Son, Erik Janzén, Wolfgang J. Choyke, P. Ordejón
Authors: Yue Ke, Catherine Moisson, S. Gaan, R.M. Feenstra, Robert P. Devaty, Wolfgang J. Choyke
Abstract: The effects of initial surface morphology on the early stages of porous SiC formation under highly biased photoelectrochemical etching conditions are discussed. We etched both Si-face and C-face polished n-type 6H SiC with different surface finishes prepared either by mechanical polishing or by chemical mechanical polishing at NOVASiC. For both Si-face and C-face porous SiC samples, a variety of surface and cross sectional porous morphologies, due to different surface finishes, are observed. The proposed explanation is based on the spatial distribution of holes at the interface of the SiC and electrolyte inside the semiconductor.
Authors: Peter Deák, B. Aradi, Adam Gali, Uwe Gerstmann, Wolfgang J. Choyke
Authors: Y. Shishkin, Yue Ke, Robert P. Devaty, Wolfgang J. Choyke
Abstract: A brief historical development of porous SiC and GaN is given. SEM images of nine porous morphologies in 4H, 6H and 3C SiC are shown along with anodization details. Similarly, two porous GaN morphologies are presented. Applications and future prospects are discussed.
Authors: T. Hornos, Adam Gali, Robert P. Devaty, Wolfgang J. Choyke
Abstract: Ab initio supercell calculations have been carried out to investigate the doping of phosphorus in chemical vapor deposited (CVD) SiC layers. CVD conditions have been simulated by using the appropriate chemical potentials for hydrogen and phosphorus (P). We found that the most abundant defect is P at Si-site followed by P at C-site. The calculated concentrations of the P-donors and free carriers in CVD grown SiC agree with the experimental results.
Authors: S.G. Sridhara, Song Bai, O. Shigiltchoff, Robert P. Devaty, Wolfgang J. Choyke
Authors: Adam Gali, Peter Deák, E. Rauls, P. Ordejón, F.H.C. Carlsson, Ivan G. Ivanov, Nguyen Tien Son, Erik Janzén, Wolfgang J. Choyke
Authors: Charíya Virojanadara, M. Hetzel, Leif I. Johansson, Wolfgang J. Choyke, Ulrich Starke
Abstract: The atomic and electronic structure of 4H-SiC(1 1 02) surfaces were investigated using scanning tunneling microscopy (STM), low-energy electron diffraction (LEED) and photoemission (PES). Two well ordered phases existing on this surface, i.e. (2×1) and c(2×2) are discussed. The (2×1) phase consists of a Si adlayer which is topped by an array of ordered Si-nanowires with electronic states confined to one dimension. For the c(2×2) phase STM indicates the presence of adatoms and PES a surface composition close to bulk SiC stoichiometry. A detailed atomic model for this c(2×2) phase is proposed.
Authors: S.G. Sridhara, D.G. Nizhner, Robert P. Devaty, Wolfgang J. Choyke, T. Troffer, Gerhard Pensl, David J. Larkin, H.S. Kong
Authors: G.T. Andrews, Maynard J. Clouter, B. Mroz, Y. Shishkin, Yue Ke, Robert P. Devaty, Wolfgang J. Choyke
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