Ordering and intermixing at metallic interfaces
thesisposted on 15.12.2014, 10:40 by Paul. Steadman
Using surface X-ray diffraction and synchroton radiation the growth modes and structures of the metallic systems Cr on Cu(001), Cr on Ag(001) and Fe on Cu(001) have been studied.;The growth of Cr on Cu(001) was found to be disordered at all substrate temperatures. The growth at 100K and 300K was consistent with a random deposition model. In contrast the growth performed at higher substrate temperatures is consistent with significant surface diffusion allowing interlayer mass transport. The growth of Cr on Ag(001) is highly sensitive to the sample temperature. At 100K a poorly defined layer-by-layer growth mode is found and at 300K disordered growth takes place. At higher substrate temperatures coating of adsorbate atoms by substrate atoms describes the data. The growth of Fe on Cu(001) proceeds as layer-by-layer with some atoms sitting in non-epitaxial positions. The lateral order of the Fe islands oscillate in phase with the coverage.;In he case of Fe grown on Cu(001) at room temperature intermixing of the two atomic species takes place up to 4ML. After 6.2ML no intermixing could be detected. A 1.0ML Cr film grown on Ag(001) at 440K consists of an almost complete Ag film on top of an almost Cr film. A 2 and 5ML coverage of Cr on Ag(001) grown at 100K had only 50 and 80% of atoms respectively in epitaxial positions. In all of the films studied changes in the spacings of the film were found compared to a model which assumes the pseudomorphic packing of hard sphere radii.