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ZrO2 films with a sub-10-nm thickness and a roughness of about 0.2 nm have been prepared on Si(001) by a sol-gel process based on zirconium-(IV)-n-propoxide. The topography of the obtained samples has been controlled by atomic force microscopy. Chemical composition and interface reactions of the deposited films have been studied by x-ray photoemission spectroscopy and Auger electron spectroscopy. The ZrO2 films are stable against heating (up to 700 °C) in a moderate oxygen atmosphere (2×10-5 mbar oxygen partial pressure). Minor changes in the surface composition occur after rapid annealing up to 1000 °C. [ABSTRACT FROM AUTHOR]

Using mirror electron microscopy (MEM) as spatially resolving method the nucleation of chemical waves in catalytic CO oxidation on a Pt(110) surface was investigated in the 10-5 mbar range. The waves nucleated at an electrically insulating impurity of approximately 15 μm diameter (the “defect”) which most likely represents a diamond particle left over from the polishing process. Nucleation events are initiated by a dynamic process in a boundary layer of approximately 1 μm width between the defect and the surrounding Pt(110) surface. Depending on the parameter choice the fronts/pulses do not escape from the vicinity of the defect and later on die out or, in a supercritical nucleation, propagate across the surface. Asymmetric nucleation leads to spiral waves which remain pinned to the defect. The defect has a kind of steering effect causing chemical waves to collide exactly at the defect. This steering effect is evidently due to a distortion of the substrate lattice in the vicinity of the defect. [ABSTRACT FROM AUTHOR]

The article explains the preparation, properties and the reactions of the high- quality Zr[O.sub.2]/Si(001) thin films that are prepared by a sol-gel process. These films are shown to be highly stable against heating.

Heating 5at.% (on A-site) La-doped SrTiO3(100) single crystals in an ambient atmosphere at 1300°C for 120 h results in the formation of insulating islands on top of the surface with typical dimensions of up to 50 μm. The islands and the surface between them were investigated by spectroscopic Metastable Impact Electron Emission Microscopy (specMIEEM) and Photoelectron Emission Microscopy in order to determine its electronic and geometric structure. The comparison of specMIEEM results with MIES (Metastable Impact Electron Spectroscopy) spectra from stoichiometric SrO shows that the insulating islands, which most likely consist of SrO, are at least partly covered by another species, probably SrO2. All these islands are surrounded by 2–3 μm wide haloes. The electronic structure of these haloes is quite different from that of SrO and SrTiO3 but similar to the electronic structure of TiO2 or Ti2O3. It is suggested that the depletion of SrO from Ruddlesden-Popper (Sr n + 1Ti nO3 n + 1) phases results in the formation of SrO islands. [ABSTRACT FROM AUTHOR]

Reflection high-energy electron diffraction intensities during molecular beam epitaxy growth of Ni on W(110) were studied. The damping and polar angle dependence of the observed oscillations are discussed. Intensity oscillations during preparation of a Ni/Cu superlattice are also reported. [ABSTRACT FROM AUTHOR]

ZrO2 films with a thickness as low as 4 nm and a roughness of about 0.2 nm have been deposited on Si(001) by a sol-gel process. After pyrolysis in air clean and dense ZrO2 films were obtained. To simulate the influence of thermal processes in complementary metal-oxide-semiconductor fabrication on high-k gate oxides, our samples have been subjected to heat treatments up to 1000 °C. The chemical composition of the ZrO2 films and of the interface region has been monitored by Auger electron spectroscopy (AES) and AES depth profiles. No notable chemical changes in the interface region have been detected after heating at 700 °C in 2×10-5 mbar oxygen partial pressure and rapid annealing to 1000 °C. At 700 °C and 10-4 mbar oxygen partial pressure an intermediate interface layer starts to grow by oxidation of the Si substrate. Annealing above 700 °C in UHV leads to the destruction of the sample. Loss of oxygen is accompanied with the formation of islands containing Zr and Si and of holes extending up to 200 nm deep into the Si substrate. [ABSTRACT FROM AUTHOR]

A near ambient pressure low-energy electron microscope (NAP-LEEM) has recently been constructed, that allows in situ imaging of surfaces up to a pressure of 10 -1  mbar. Here we report on pattern formation in catalytic CO oxidation on a Pt(110) single crystal surface and on a polycrystalline Pt foil in the 10 -2  mbar range, operating the microscope in the mirror electron microscopy (MEM) and in the LEEM mode. Excitations localized at structural defects and spiral wave fragments have been observed., (Copyright © 2019. Published by Elsevier B.V.)

Dilute nitride III-V nanowires (NWs) possess great potential as building blocks in future optoelectronical and electrochemical devices. Here, we provide evidence for the growth of GaP/GaPN core-shell NWs via metalorganic vapor phase epitaxy, both on GaP(111)B and on GaP/Si(111) hetero-substrates. The NW morphology meets the common needs for use in applications, i.e. they are straight and vertically oriented to the substrate as well as homogeneous in length. Moreover, no parasitical island growth is observed. Nitrogen was found to be incorporated on group V sites as determined from transmission electron microscopy (TEM) and Raman spectroscopy. Together with the incorporation of N, the NWs exhibit strong photoluminescence in the visible range, which we attribute to radiative recombination at N-related deep states. Independently of the N incorporation, a peculiar facet formation was found, with {110} facets at the top and {112} at the bottom of the NWs. TEM reveals that this phenomenon is related to different stacking fault densities within the zinc blende structure, which lead to different effective surface energies for the bottom and the top of the NWs.