CHARACTERIZATION OF CA AGGREGATES ON CAF2 (111)-SURFACES BY ATOMIC-FORCE, XPS, AND FLUORESCENCE MICROSCOPY

In this contribution we report on the metallization of (111)-surfaces of CaF2 single crystals as a result of low energy electron irradiation . An in-situ control of the spatial distribution of the metal coverage was obtained by rapidly scanning a low intensity electron beam across the irradiated area and monitoring the STE luminescence radiation. Me tallized spots are identified by a reduced luminescence intensity. Sur face stoichiometry was tested by XPS-microscopy. The spatially resolve d observation of line intensities as well as line shifts revealed an e ffective metallization and oxidation of the surface. Using atomic forc e microscopy we found evidence for a 3-dimensional island-like formati on of Ca aggregates with a size up to 12 mum diameter. Results for clu ster formation in the center of the irradiating beam are compared to t hose from outer regions. The size distribution of the aggregates repro duces the different levels of electron dosage across the beam profile.