Nucleation and stacking faults on the Iridium (111) surface

By analyzing the saturation island density during nucleation in homoepitaxial growth on Ir(111) using scanning tunneling microscopy (STM), parameters of adatom diffusion could be determined. Furthermore, for the first time also the diffusion barrier for the dimer was determined by this method. These parameters are in perfect agreement with the respective results from filed ion microscopy (FIM). In extension of these measurements, an important quantity in surface science, namely, the binding energy of an adsorbed dimer, was determined. Comparing the systems Ir(111), Al(111), and Pt(111) shows that the binding energy scales with the cohesive energy (E_(b,2) = (0.11 +/- 0.01) E_(coh)), as expected in a simple model of nearest-neighbor bonds. In addition it was shown, that the binding energies determined by FIM are in error due to neglected processes at step edges. The formation of stacking-faults was observed in the system Ir/Ir(111) under a wide range of deposition parameters. A quantitative model can explain the observations: Stacking-faults form out of small clusters that can occupy faulted sites with significant probability in thermal equilibrium. Metastable areas in the wrong stacking sequence then grow out of these clusters by sufficiently fast addition of adatoms. Upon further growth, islands in the same stacking coalesce, but islands in different stacking sequences do not. In the latter case, atoms can, however, move to the energetically favorable, regular stacking via a kink-flip process (self-healing). In the ideal case this leads to a complete disappearance of the wrong stacking and a defect-free film evolves. This effect can be observed in situ by annealing experiments. The electronic structure of the two phases is very different, as can be shown using voltage-dependent STM. Theoretical calculations support the respective experiments.

Grantor dc:publisher

Publikationsserver der RWTH Aachen University

Year dc:date

2003

Author dc:creator

• Busse, Carsten

Contributors dc:contributor

• Michely, Thomas

• info:eu-repo/classification/ddc/530
• Iridium
• Kristallfläche
• Homoepitaxie
• Keimbildung
• Stapelfehler
• Rastertunnelmikroskopie
• Physik
• Diffusion
• Oberfläche
• fcc(111)

Statement dc:rights

• info:eu-repo/semantics/openAccess

Language dc:language

eng

Identifier

https://publications.rwth-aachen.de/search?p=id:%22RWTH-CONV-123562%22

OAI identifier oai:identifier

oai:publications.rwth-aachen.de:61956