Co induced nanocrystals on Ge(001)

T.F. Mocking, G. Hlawacek, Henricus J.W. Zandvliet

Research output: Contribution to journalArticleAcademicpeer-review


The deposition of several monolayers of cobalt on germanium (001) substrates results in the formation of two types of clusters: flat-topped and peaked nanocrystals. Scanning tunneling spectroscopy and helium ion microscopy measurements reveal that these nanocrystals contain cobalt. The shape evolution of the flat-topped and peaked nanocrystals as a function of their size is investigated with scanning tunneling microscopy. For small sizes the nanocrystals are compact. Beyond a critical size, however, the peaked nanocrystals exhibit an elongated shape, whilst the flat-topped nanocrystals remain compact. The shape transition of the peaked nanocrystals is driven by a competition between boundary and strain energies. For small sizes the boundary energy is the dominant term leading to a minimization of the peaked nanocrystal's perimeter, whereas at larger sizes the strain energy wins resulting in a maximization of the perimeter. On the top facet of the flat-topped nanocrystals one-dimensional structures are observed that are comprised of small square shaped units of about 1 nm2. Time-resolved scanning tunneling microscopy measurements reveal that these square shaped units are dynamic at room temperature
Original languageEnglish
Pages (from-to)924-927
Number of pages4
JournalSurface science
Issue number11-12
Publication statusPublished - 2012


  • METIS-286055
  • Optics (see also 3311)Solid state physics (see also 2307)Niet in een andere rubriek onder te brengen
  • IR-84669


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