TY - CHAP A1 - Guizzardi, Giancarlo A1 - Wagner, Gerd A1 - Sinderen, Marten van ED - Büchel, Gregor ED - Klein, Bertin T1 - A Formal Theory of Conceptual Modeling Universals Y1 - 2004 UR - http://sunsite.informatik.rwth-aachen.de/Publications/CEUR-WS/Vol-112/ ER - TY - CHAP A1 - Wagner, Gerd T1 - A UML Profile for External Agent-Object Relationship Models Y1 - 2003 ER - TY - CHAP A1 - Wagner, Gerd T1 - Web Rules Need Two Kinds of Negation Y1 - 2003 ER - TY - GEN A1 - Taveter, Kuldar A1 - Wagner, Gerd T1 - Agent-Oriented Enterprise Modeling Based on Business Rules Y1 - 2001 ER - TY - CHAP A1 - Wagner, Gerd T1 - A Database needs two knds of Negation Y1 - 1991 ER - TY - GEN A1 - Schmeißer, Dieter A1 - Irmscher, Klaus A1 - Wagner, Gerd T1 - Photoelectron spectra of Al dopants in 4H-SiC T2 - Materials Science & Engineering B N2 - Al-doped 4H-SiC epitaxial layers were grown in a hot-wall chemical vapor deposition (CVD) system on commercial 4H-SiC substrates (CREE). The incorporation of Aluminum has been studied in the concentration range from 2*1014cm-3 up to 3*1020cm-3. Epitaxial layers with doping concentration NA-ND> 1019cm-3 were studied by HV-TEM and synchrotron radiation investigations. In the concentration range from 1*1019cm-3 to 3*1020 cm-3, measured by SIMS and Hall investigations, no Aluminum precipitation were detected in the grown layers. For SiC samples with an Al concentration of 1020cm-3 we have been able to detect the Al2p photoemission signal. The Al2p signal is recorded through the oxide layer (thickness of about 0.4nm), it has a main contribution at a binding energy of 73eV which corresponds to the energy typical for elemental Al0. In spectra excited with higher photon energies the sampled photoelectrons originate from deeper layers. In these data we notice an additional shoulder in the Al2p signal at around 71eV. The evidence of two contributions is attributed to the fact that Al is incorporated at different lattice sites. As the latter data represent more bulk like properties we argue that Al in the bulk SiC occupies both, substitutional lattice sites and interstitial sites while in the surface near regions Al is found only at substitutional lattice sites. KW - Photoelectron KW - Spectra KW - 4H-SiC Y1 - 2003 SN - 0921-5107 SN - 1873-4944 VL - 102 IS - 1-3 SP - 284 EP - 288 ER - TY - GEN A1 - Schwarzkopf, Jutta A1 - Dirsyte, R. A1 - Devi, A. A1 - Kwasniewski, A. A1 - Schmidbauer, M. A1 - Wagner, Gerd A1 - Michling, Marcel A1 - Schmeißer, Dieter A1 - Fornari, Robert T1 - Influence of Na on the structure of Bi4Ti3O12 films deposited by liquid-delivery spin MOCVD T2 - Thin solid films Y1 - 2011 SN - 0040-6090 VL - 519 IS - 17 SP - 5754 EP - 5759 ER -