Observations of reversible and irreversible structural transitions of cobalt on Si (1 1 1) with LEEM

R.J. Phaneuf, Y. Hong, Sebastian Horch, P.A. Bennett

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We present real time images of the evolution of the structure of the Si (111) surface during the deposition of cobalt at elevated temperatures, acquired using low-energy electron microscopy. The system follows a sequence of coexisting ordered and disordered phases, consistent with two-dimensional eutectic behavior. Reversible temperature driven transitions are observed between the ordered Si (111)-(7 x 7) reconstructed phase and a disordered lattice gas of Co-containing ring-clusters (RC), indicating a local equilibrium between these structures. Only irreversible temperature driven transitions from an ordered (root 7 x root 7)-RC phase to the disordered phase are observed. The nucleation and growth of stable islands, mostly CoSi2, depletes the Go-rich (root 7 x root 7) structure of Co, resulting in the formation and growth of adjacent regions of the Co-poor disordered "(1 x 1)"-RC phase. (C) 1999 Elsevier Science Ltd. All rights reserved.
Original languageEnglish
Issue number1
Pages (from-to)13-20
Publication statusPublished - 1999
Externally publishedYes


  • Surfaces
  • Surface phase transitions
  • Surface phase separation
  • Silicides
  • Electron microscopy
  • Low-energy electron microscopy


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