Berlin 2005 – wissenschaftliches Programm

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O: Oberflächenphysik

O 52: Elektronische Struktur IV

O 52.8: Vortrag

Mittwoch, 9. März 2005, 12:30–12:45, TU EB301

Characterization of nearly free electron bands in thin Al-Mg alloy films on Si(111) — •Massimo Tallarida¹, Lucia Aballe², Ashwani Kumar¹, Sudipto Roy Barman³, and Karsten Horn¹ — ¹Fritz-Haber-Institut der MPG, Berlin — ²ELETTRA SpA, Trieste, Italy — ³UGC-DAE Consortium, Indore, Indien

Thin films of Al-Mg alloys have been grown on Si(111) by MBE over a wide range of compositions, and were characterized by angle-resolved photoemission. For Al-rich alloys, electron confinement leads to the occurrence of quantum well states, and a surface state similar to that in the Al/Si(111) film is found. For Mg-rich compositions, only a broad surface state is observed. The occurrence of quantum well states and the surface state, and their binding energy dependence on alloy composition is explained in terms of the virtual crystal approximation, with an average electron density in the alloy system. The dispersion of the quantum well states in a direction parallel to the film shows a nearly free electron behaviour similar to that found in Al/Si(111). The variation of electron density in these alloy films open the way for a study of more complex metallic systems, e.g. an investigation of the influence of electron density of the electromagnetic response.