Mesoscopic-scale observations of surface alloying, surface phase transitions, domain coarsening, and 3-D island growth: Pb on Cu(100)
Low energy electron microscopy (LEEM) is used to investigate the dynamics of Pb overlayer growth on Cu(100). By following changes in surface morphology during Pb deposition, the amount of Cu transported to the surface as the Pb first alloys into the surface during formation of the c(4x4) phase and subsequently de-alloys during conversion to the c(2x2) phase is measured. The authors find that the added coverage of Cu during alloying is consistent with the proposed model for the c(4x4) alloy phase, but the added coverage during de-alloying is not consistent with the accepted model for the c(2x2) phase. To account for the discrepancy, the authors propose that Cu atoms are incorporated in the c(2x2) structure. Island growth and step advancement during the transition from the c(2x2) to c(5{radical}2x{radical}2)R45{degree} structure agrees with this model. The authors also use the LEEM to identify the order and temperature of the two-dimensional melting phase transitions for the three Pb/Cu(100) surface structures. Phase transitions for the c(5{radical}2x{radical}2)R45{degree} and c(4x4) structures are first-order, but the c(2x2) transition is second order. They determine that rotational domains of the c(5{radical}2x{radical}2)R45{degree} structure coarsen from nanometer- to micron-sized dimensions with relatively mild heating ({approximately}120 C), whereas coarsening of c(4x4) domains requires considerably higher temperatures ({approximately}400 C). In studies of three-dimensional island formation, they find that the islands grow asymmetrically with an orientational dependence that is directly correlated with the domain structure of the underlying c(5{radical}2x{radical}2)R45{degree} phase.
- Research Organization:
- Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Sandia National Lab. (SNL-CA), Livermore, CA (United States)
- Sponsoring Organization:
- US Department of Energy (US)
- DOE Contract Number:
- AC04-94AL85000
- OSTI ID:
- 755629
- Report Number(s):
- SAND2000-0588C; TRN: AH200021%%62
- Resource Relation:
- Conference: U.S. - Japan Seminar on Mesoscopic Phenomena on Surface, Park City, UT (US), 04/02/2000--04/08/2000; Other Information: PBD: 23 May 2000
- Country of Publication:
- United States
- Language:
- English
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