Crystal Orientation of Silver Films on Silicon Surfaces Revealed by Surface X-Ray Diffraction

We have studied the crystal orientation of Ag thin films on a${\rm Si}(111)(\sqrt{3} \times \sqrt{3})\mbox{-Ag}$surface using grazing incidence X-ray diffraction with synchrotron radiation. After preparation of a${\rm Si}(111)(\sqrt{3} \times \sqrt{3})\mbox{-Ag}$surface, 50 ML Ag was deposited on the${\rm Si}(111)(\sqrt{3} \times \sqrt{3})\mbox{-Ag}$at the substrate temperature of 50–300 K. We found the$\sqrt{3}$structure at the interface. As for the Ag film, the Ag}111{ plane was mainly grown on the surface. The domain size of the Ag films strongly depends on the substrate temperature of the deposition. The domain size is found to be regulated by an original domain size of the${\rm Si}(111)(\sqrt{3} \times \sqrt{3})\mbox{-Ag}$surface before Ag deposition, which relates to the surface-structural phase transition. By scattering intensity measurements in the reciprocal lattice space, we found streaky scattering along the$[11{\bar 2}]$direction parallel to the surface. This scattering is thought to originate from the CTR (crystal truncation rod) scattering from a sidewall plane of the Ag {111} nanometer-scale crystals.