ISSN:
1089-7550
Source:
AIP Digital Archive
Topics:
Physics
Notes:
Interface formation for Ti, Co, Pd, and Au overlayers grown on thin epitaxial CaF2 layers on Si(111) have been investigated with photoelectron spectroscopy and low-energy electron diffraction. In general, metal overlayer growth leads to rapid attenuation of emission from the substrate CaF2 core levels, but the low-energy electron diffraction (LEED) results demonstrate the persistence of surface order to high coverages, indicating the growth of small clusters followed by coalescence. The photoemission results showed that Au deposition produces sharp metal/insulator interfaces. In contrast, signs of disruption were found for Ti, Co, and Pd deposition. For Au and Pd, metal-induced energy shifts of ∼1 eV in the CaF2 core levels and valence bands were observed; Ti and Co deposition induced smaller shifts. This indicates that the Fermi level in the CaF2 layer depends on the electronegativity of the metal overlayer. Annealing at 200–300 °C produced dramatic changes in the overlayer morphology with reappearance of the photoemission signals of CaF2 and its LEED pattern as large metal clusters were formed and the CaF2 surface was exposed. The photoemission results also indicate that metal-induced reaction with Si occurs upon annealing.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1063/1.344486
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