The Growth of Thin Epitaxial Copper Films on Ruthenium (0001)and Oxygen-Precovered Ruthenium (0001) as studied by x-rayphotoelectron diffraction. University of California, Davis, Department of Physics, Ph.D. Thesis
- Univ. of California, Davis, CA (United States)
In the first part of this dissertation, the variation of mean emitter depths with direction for core photoelectron emission from single crystals, including the effects of both isotropic inelastic scattering and single and multiple elastic scattering was theoretically studied. The mean emitter depth was found to vary by as much as ±30% with direction. In the second part of this dissertation, x-ray photoelectron diffraction (XPD) was used to study the structure and growth mechanisms of Cu films grown on a clean and an oxygen-precovered Ru(0001) surface. Experimental Cu 2p3/2 (Ekin = 556 eV) and Ru 3d (Ekin = 1205 eV) intensities were measured for Cu coverages from submonolayer up to several monolayer (ML) on the clean Ru(0001) surface. In addition, the O 1s (Ekin = 958 eV) intensity was measured for Cu grown on oxygen precovered Ru(0001). These XPD intensities have been analyzed using single scattering cluster (SSC) and multiple scattering cluster (MSC) models. The first Cu layer has been found to grow pseudomorphically on the Ru(0001) surface in agreement with prior studies of the Cu/Ru(0001) system. Thus, the initial growth is layer-by-layer. For higher coverages, XPD shows that the short-range structure of the Cu films is fcc Cu(111), but with significant interlayer relaxation (compared to bulk Cu(111)) that persists up to >8 ML. When oxygen is preadsorbed on the Ru(0001) surface before Cu film growth (possibly to act as a surfactant promoting smoother growth), XPD shows that the first ~3 ML of Cu grow as 3-D islands. In addition, XPD shows that, during Cu growth, all of the oxygen "floats" on the CU surface, in contrast to prior studies which found that 30% of the oxygen remains at the Cu/Ru intetiace. XPD also indicates that the oxygen is highly disordered on the Cu overlayer surface. In thicker layers with oxygen prsent, the Cu grows as Cu(111) with equal occupations of two possible domains rotated by 1800 from each other. In general, this work demonstrates the considerable usefulness of XPD in studying epitaxial overlayer growth with and without surfactants present.
- Research Organization:
- Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- AC03-76SF00098; N0014-90-5-1457; N00014-94-1-0162
- OSTI ID:
- 6432
- Report Number(s):
- LBNL-42191; ON: DE00006432
- Country of Publication:
- United States
- Language:
- English
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