Low-energy electron microscopy of layer spacings and quantum electronic structure of ultrathin films

Laterally resolved measurements of the quantum size effect in electron reflectivity are made with low-energy electron microscopy on Cu films on a W(110) surface. These measurements discriminate quantum interference peaks (QIPs) from regions of different film thickness. A Kronig-Penney model and a phase accumulation model are used to analyse QIPs to obtain average layer spacings for different film thicknesses and unoccupied band structure above the vacuum level. The average layer spacing is found to slightly exceed the strained layer spacing predicted by elasticity theory. The experimentally determined (k) also agree with theoretical band structure from the Brillouin zone centre to the zone edge in the GammaL direction. Copyright (C) 2005 John Wiley Sons, Ltd.