Low-energy electron-diffraction determination of the structure of successively deposited ordered layers of Cd on Ti(0001). II. Second, third, and fourth layers

Abstract

The study of the structural aspects of the initial stages of epitaxial growth of Cd on Ti(0001) by LEED (low-energy electron-diffraction) analysis is carried out for two, three, and four deposited layers of Cd. A structure analysis of the 2nd (1 × 1) phase confirms it to consist of two complete close-packed atomic layers of Cd, separated by the in erlayer spacing along $〈0001〉$ in bulk Cd (2.81 Å). The interplanar Ti-Cd distance at the interface (2.63 Å) has increased slightly with respect to its value when only a single layer of Cd was adsorbed on the Ti(0001) surface (2.57 Å). The second-layer Cd atoms lie in the sites which continue hexagonal close packing of the first Cd layer and the first Ti layer. The structure of the third atomic layer, although essentially known, cannot be directly proven by model calculations because of limitations of the computer program available at this time. However, a four-layer-thick Cd film is shown to give the same LEED spectra as a semi-infinite Cd(0001) crystal.