Quantum-well states in ultrathin aluminium films on Si(111)

Investigations of the thickness dependent electronic structure of ultrathin aluminium films deposited on Si(1 1 1) 7 x 7 using angle resolved photoele ctron spectroscopy show the first experimental observation of quantum-well states in this system. Deposition at 100 K favours an abrupt and homogeneou s interface and the growth of an epitaxial, quasi two-dimensional Al(1 1 1) overlayer of good crystalline quality, making possible the observation of overlayer states for thicknesses up to 30 Al monolayers. We obtain the deca y length of the Al(1 1 1) surface state as well as the energy-dependent pha se shift of the electron waves at the Al/Si interface. (C) 2001 Elsevier Sc ience B.V. All rights reserved.