Structural evolution and atomic structure of ultrahigh vacuum deposited Au thin films on silicon at low temperatures

Structural evolution and atomic structure of ultrahigh vacuum deposited Au thin films on silicon at low temperatures have been investigated by in situ reflection high energy electron diffraction and transmission electron microscopy. A discontinuous amorphous layer, up to 3.5 nm in thickness, was found to be present at the Au(001)Si interface in as-deposited samples. On the other hand, no amorphous interlayer was found to be present at the Au(111)Si interface. The interface is flat on the atomic scale. In both (001) and (111) samples annealed at 220°C or higher temperatures, no amorphous intermixed layer was observed to be present. After annealing at 360°C for 1 h, Au grains were found to agglomerate in (001) samples whereas the textured Au layer is still continuous with a rather flat AuSi interface in the (111) samples. Severe islanding was found to occur in both (001) and (111) samples annealed at 400°C for 1 h.