Selected Publications - 2007:
1) Heteroepitaxial praseodymium sesquioxide films on Si(111): A new model catalyst system for praseodymium oxide based catalysts
A. Schaefer, Yu. Borchert and M. Bäumer
University of Bremen, Institute of Applied and Physical Chemistry, Leobener Str. 2, 28359 Bremen, Germany
T. Schroeder, G. Lupina, Ch. Wenger and J. Dabrowski
IHP-Microelectronics, Im Technologiepark 25, 15236 Frankfurt (Oder), Germany
Surface Science 601, 1473 (2007)
The structure, growth and stoichiometry of heteroepitaxial Pr2O3 films on Si(111) were characterized by a combined RHEED, XRD, XPS and UPS study in view of future applications as a surface science model catalyst system. RHEED and XRD confirm the growth of a (0001) oriented hexagonal Pr2O3 phase on Si(111), matching the surface symmetry by aligning the <10-10> oxide in-plane direction along the <01-1> Si azimuth. After an initial nucleation stage RHEED growth oscillation studies point to a Frank-van der Merwe growth mode up to a thickness of approximately 12 nm. XPS and UPS prove that the initial growth of the Pr2O3 layer on Si up to ~1 nm thickness is characterized by an interface reaction with Si. Nevertheless stoichiometric Pr2O3 films of high crystalline quality form on top of these Pr-silicate containing interlayers.
PDF published by Elsevier Science (http://www.elsevier.com/wps/find/journaldescription.cws_home/505676/description?navopenmenu=-2)
2) Self-assembled Ge nanocrystals on high-k cubic Pr2O3(111)/Si(111) support systems
T. Schroeder, I. Costina, A. Giussani, G. Weidner, O. Seifarth, Ch. Wenger, and P. Zaumseil
IHP-Microelectronics, Im Technologiepark 25, 15236 Frankfurt (Oder), Germany
C. Mocuta and T. H. Metzger
European Synchrotron Radiation Facility, BP 220, 38043 Grenoble, France
D. Geiger and H. Lichte
Technical University Dresden, Zellescher Weg 16, 01062 Dresden, Germany
JOURNAL OF APPLIED PHYSICS 102, 034107 (2007)
The stoichiometry, structure, and defects of self-assembled heteroepitaxial Ge nanodots on twin-free type B oriented cubic Pr2O3(111) layers on Si(111) substrates are studied to shed light on the fundamental physics of nanocrystal based nonvolatile memory effects. X-ray photoelectron spectroscopy studies prove the high stoichiometric purity of the Ge nanodots on the cubic Pr2O3(111)/Si(111) support system. Synchrotron based x-ray diffraction, including anomalous scattering techniques, was applied to determine the epitaxial relationship, showing that the heteroepitaxial Ge(111) nanodots crystallize in the cubic diamond structure with an exclusive type A stacking configuration with respect to Si(111). Grazing incidence small angle x-ray scattering was used in addition to analyze the average shape, size, and distance parameters of the single crystalline Ge nanocrystal ensemble. Furthermore, transmission electron micrographs report that partial dislocations are the prevailing extended defect structure in the Ge nanodots, mainly induced by surface roughness on the atomic scale of the cubic Pr2O3(111) support. © 2007 American Institute of Physics. [DOI: 10.1063/1.2767374]
PDF published by Journal of Applied Physics available online at http://jap.aip.org