Influence of a heteroepitaxial interface with large lattice mismatch on the low temperature growth of a film

Abstract

We report on the influence of a heteroepitaxial interface Pb/Cu(100) on the growth of a Pb film at 150 K using helium beam scattering, low-energy electron diffraction (LEED), and Auger electron spectroscopy. The large lattice mismatch, the difference in bonding strengths, and symmetry between substrate and film produce a rather complex growth pattern. The growth mode in the very early stage is strongly influenced by the Pb/Cu interface, evolving from ordered growth (first layer) to disordered growth (second and third layers) and ordered quasi-layer-by-layer growth (from the fourth to the sixteenth layers). The LEED pattern shows the presence of Pb(111) exposed surfaces with domains rotated by 90°. The envelope of helium beam intensity reveals evidence of quantum size effects and of increasing interface width. The broadening of in-phase diffraction profiles indicates formation of mosaic surface structures. Better layer-by-layer growth is achieved by annealing the disordered second layer. Depending on substrate temperature, first layers with different structures are obtained. These first layer structures dramatically affect the subsequent growth at low temperature.