Preparation of Silicon (111) Surface for Epitaxial Growth of III-Nitride Structures by MBE

The paper presents a technology for preparing the silicon Si(111) substrates surface for the III-nitride compounds epitaxial growth by molecular beam epitaxy technique. The technology includes the following stages: chemical surface pretreatment by the Shiraki method, bakeout in the preliminary annealing chamber, the substrates heating in the growth chamber in order to obtain an atomically clean and ordered silicon surface, the samples cooling with subsequent registration of the (7x7) superstructure. The search for surface preparation conditions was carried out using (1) high-energy electron diffraction, which in situ revealed carbon contamination in the form of silicon carbide compounds formed during high-temperature heating of silicon, and (2) high-resolution optical microscopy, which recorded dislocation slip lines caused by a temperature gradient in sample heating process. For uniform heating/cooling of the substrate and suppression of the process of generation and slip of dislocations that appear at the edges of the substrate, the substrate mounting arrangement was modified. It has been demonstrated that the surface of Si(111) substrates prepared using the proposed technology is suitable for the epitaxial growth of III-nitride structures.