Determination of Ge(001) step free energies

Scanning tunneling microscopy images of vicinal Ge(001) have been analyzed to determine the distribution of kinks. From this distribution, kink formation energies and step-free energies of the single-layer steps on Ge(001) have been extracted. Using the experimentally determined step free energies, it is predicted that Ge(001) thermally roughens prior to melting. This roughening transition, which is predicted to occur at 900±100 K, sheds light on the interpretation of the high-temperature phase transition of Ge(001).