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Alternative representation of QW Phase accumulation model
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Dispersion of k(E)
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Synchrotron radiation photoemission spectroscopy ISA Aarhus University Maximum Energy 580 MeV Max Current 250 mA Lifetime 15 hours SGM1 30-400 eV 10 10 photons/sec @130 eV
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Photoelectron spectroscopy Core levels – Chemical reactions/mixing – Growth modes Valence bands – Electronic levels relevant for optics
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Scanning film thickness by moving wedge through laser or synchrotron beam Wedge-shaped metal film Sample moved into shadow of shield. Evaporation rate ~1 ML per minute Triangular domains ~200 nm Ag(111) LEED-pattern - only one type of domains Width of synchrotron beam AFM
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Film growth - Si2p spectra Growth at 170 K leads to exponential decay of Si2p levels with ~5Å decay rate. Room temperature annealing of the film leads to growth of large atomically flat domains. Areas with low Ag coverage are formed. Annealing
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Cu buffer layer Cu wedge under 10-ML Ag film 3 ML Cu: disordered film 6-7 ML Cu: optimum for Ag overlayer > 7 ML Cu: coupling of overlayer and substrate levels - double peaks - avoided crossings
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Effect of Cu buffer layer
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QW levels and film roughness 024681012141618202224 -2.5 -2 -1.5 -0.5 0 Thickness (ML) Binding Energy (eV) Film thickness variations expected within probed area Variations within a few atomic layer give broad peaks in photoemission Beam size on sample ~1 mm
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