Abstract
For the first time the step-edge energies have been measured for a superstructure resulting from nonpolar/polar heteroepitaxy. Using scanning tunneling microscopy, we have investigated the morphology of the Ge/GaAs(001)-(1 × 2) reconstructed surface using substrates miscut by 1° and 2° toward the [110] direction to expose the A-type steps. The superstructure has well-defined step edges and smooth terraces, even when the initial substrate is rough. The primary defect structures are antiphase domain boundaries remaining from the formation of the (1 × 2) reconstruction. The kink energies are similar to those for the A-type steps on both the GaAs(001)-(2 × 4) and Si(100)-(2 × 1) surfaces. In addition, there is an apparent kink-kink attraction of about 120 meV between nearest-neighbor kinks. Using the model incorporating nearest-neighbor interactions between kinks developed for the Ge/GaAs(001)-(1 × 2) superstructure, the kink-kink repulsion observed on GaAs(001)-(2 × 4) is discussed quantitatively and shown to involve energies significantly higher than those which could be reasonably attributed to dipole-dipole interactions.
Published Version
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