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.