Initial growth mode of ultrathin Ag films on an Al(111) surface

Abstract

The initial growth mode of ultrathin Ag films grown on an Al(111) surface was studied using Auger electron spectroscopy, low-energy electron diffraction (LEED) and x-ray photoelectron spectroscopy. Although Al and Ag have the same fcc bulk structure with nearly the same lattice parameters and a similar homoepitaxial growth mode, the initial growth mode of Ag on an Al(111) surface showed quite an unexpected behavior. As silver was deposited on an Al(111) surface at room temperature, the intensities of LEED spots diminished exponentially up to about 2 monolayer (ML), and the LEED pattern completely disappeared between 2 to 4 ML coverage. After 4 ML thick deposition, (1x1) LEED pattern started to reappear. To explain these experimental results, we propose a growth model of Ag film on the Al(111) surface that incorporates stacking faults induced by an interface alloy formation as observed in our spectroscopic work.