Berlin 2005 – wissenschaftliches Programm
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O: Oberflächenphysik
O 49: Epitaxie und Wachstum II
O 49.9: Vortrag
Dienstag, 8. März 2005, 17:45–18:00, TU EB407
Growth and atomic structure of NiO and MnO films on Pt(111): In-situ STM experiments at elevated temperatures — •Christian Hagendorf, Henning Neddermeyer, and Wolf Widdra — Martin-Luther-Universität Halle-Wittenberg, FB Physik, Hoher Weg 8, D-06120 Halle (Saale)
Growth, atomic structure and phase transitions of NiO and MnO thin films on Pt(111) have been studied using scanning tunneling microscopy and spectroscopy (STM/STS), low-energy electron diffraction (LEED), and Auger electron spectroscopy (AES). Mn and Ni have been deposited in an O2 atmosphere (10−8−10−6 mbar) at substrate temperatures between 300−600 K. In-situ STM experiments were performed at elevated temperatures during film growth.
Depending on the substrate temperature, one-dimensional network-like Ni/O adsorbate structures or islands with (7x1) and (4x2) reconstruction are formed during the initial stages of growth. These structures transform reversibly to a (2x2) reconstruction by varying the O2 pressure between 1.5−2*10−6 mbar which has been followed by in-situ STM. After further reduction of the O2 pressure to <10−10 mbar metallic Ni islands are obtained. At higher coverages (111) oriented NiO islands are stabilized in a 3-dimensional growth mode.
MnO grows on Pt(111) at 450 K in a layer-by-layer mode. Characteristic reconstructions are observed at different coverages which are stable after deposition. Structural changes can be induced by annealing to 600 K. The results will be compared to previous investigations of NiO and MnO on Ag(001).