title: (2 x 1)-(1 x 1) phase transition on Ge(001): dimer breakup and surface roughening.
abstract: Using low energy electron microscopy, we have investigated the (2 x 1)-(1 x 1) phase transition occurring above 925 K on Ge(001). Dimer breakup has been identified as the physical origin of this transition. A quantitative description of the dimer concentration during the transition involves configuration entropy of random monomers within the dimer matrix. The dimer formation energy amounts to 1.2+/-0.3 eV. Dimer breakup promotes reversible surface disorder by step proliferation and irreversible surface roughening above 1130 K.
authors.affiliation: Solid State Physics Group, MESA+ Research Institute, University of Twente, PO Box 217, Enschede, The Netherlands.
authors.forename: Esther
authors.initials: E
authors.lastname: van Vroonhoven
authors.forename: Harold J W
authors.initials: HJ
authors.lastname: Zandvliet
authors.forename: Bene
authors.initials: B
authors.lastname: Poelsema