High stability of two-dimensional islands during surfactant-mediated epitaxial growth.

Abstract

The initial stages of surfactant-mediated epitaxial growth of Ge on Si(001):As were examined by scanning tunneling microscopy (STM). A submonolayer of Ge was deposited on Si(001):As substrates free from two-dimensional (2D) islands at 300--500 \ifmmode^\circ\else\textdegree\fi{}C. The STM images showed that two types of elongated 2D islands were formed depending on the substrate temperature during Ge deposition. The 2D islands formed at the higher temperature were found to be stable during the heating of the sample at 500 \ifmmode^\circ\else\textdegree\fi{}C. This was contrary to the 2D islands formed by Ge deposition without surfactant. These results suggest that the higher stability of the surface configuration covered by the surfactant layer is important in suppressing 3D islanding in Ge films.