Dresden 2006 – scientific programme
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O: Oberflächenphysik
O 17: Adsorption II
O 17.1: Talk
Tuesday, March 28, 2006, 11:15–11:30, TRE Phys
FORMATION OF ULTRATHIN CdS-FILMS ON CU(111) - AN IN-SITU STM and EX-SITU SXPS STUDY — •Sascha Hümann1, Peter Broekmann1, Ralf Hunger2, Thomas Mayer2, Wolfram Jaegermann2, and Klaus Wandelt1 — 1Institut für Physikalische und Theoretische Chemie der Universität Bonn, Wegelerstr. 12, 53115 Bonn — 2Institut für Materialwissenschaft, Technische Universität Darmstadt, Petersenstr. 23, 64287 Darmstadt
Electrochemical Atomic Layer Epitaxy is a useful method to grow thin layers of semiconductor compounds at solid/liquid interfaces. In this contribution we present combined ECSTM and synchrotron x-ray photoelectron spectroscopy (SXPS) data dealing with the epitaxial growth of ultrathin CdS-films on a Cu(111) electrode surface. We observed that the atomic structure and the morphology of the resulting CdS film strongly depend on the first layer adsorbed on the copper substrate. The first preparation route of the CdS-films started with a (√7x√7)R19.1∘ sulfide adlayer on the Cu(111) surface. This root 7 phase could be maintained upon emersion and successfully transferred into the UHV. We observed corresponding LEED images and SXPS data supporting the results of the ECSTM studies. Cd deposition on the root 7 sulfide phase at a potential of -375 mV vs. RHE results in the formation of a CdS-phase revealing a complex dislocation network. After transfer to UHV the composition and chemical nature of the film constituents was analysed. A different CdS phase was obtained when sulfide anions were adsorbed on the Cd precovered copper surface. The corresponding LEED pattern shows a (√3x√3)R30 unit cell.