ON THE LOW-TEMPERATURE GROWTH OF PB ON CU(100)

The morphology and structure of Pb deposits on Cu(100) between 150 and 220 K is investigated using low-energy electron diffraction (LEED), a uger electron spectroscopy (AES) and scanning tunneling microscopy (ST M). It is found that Pb grows along a [111] axis, with Pb[110] paralle l to Cu[100]. In the surface plane, this relationship of epitaxy induc es tensile stress of 3.18 in the direction of the common axis and comp ressive stress of -0.8% in the perpendicular direction. Starting from the wetting monolayer made above room temperature, the growth proceeds by a three regime sequence. The growth of a complete bilayer is follo wed by a quasi layer-by-layer regime which switches, at a temperature- dependent critical coverage, into a three-dimensional pyramidal growth mode. LEED observations suggest that the stresses are fully relaxed b y the bilayer. These results are shown to be in good agreement with pu blished thermal energy atom scattering (TEAS) data obtained on the sam e system. It is shown that the transition from the quasi layer-by-laye r regime to the three-dimensional pyramidal growth mode is triggered b y the development of islands with a triangular shape, which results in a limitation of the mass transport between atomic Pb layers. (C) 1997 Elsevier Science B.V.