Ge/SrTiO₃(001): Correlation between interface chemistry and crystallographic orientation

In this work, the desorption of a submonolayer deposit of Ge on SrTiO ₃(001) is studied by reflection high energy electron diffraction. The results are compared to those of a previous experiment done using soft x-ray photoelectron spectroscopy. Combining these techniques allows for correlating interface chemistry and crystal orientation, and for bringing clarifying elements concerning the competition between (111) and (001) crystal orientation typical for the semiconductor/perovskite epitaxial systems. Despite poor interface matching, (111)-oriented islands are stabilized at the expense of (001)-oriented islands due to the relatively low energy of their free facets. Such surface energy driven crystallographic orientation of the deposit is enhanced by the low adhesion energy characteristic of the Ge/SrTiO₃ system.