Epitaxy of Orthorhombic BaSi2 with Preferential In-Plane Crystal Orientation on Si(001): Effects of Vicinal Substrate and Annealing Temperature

Abstract

We attempted to grow orthorhombic BaSi2 epitaxial films having preferential in-plane crystallographic orientation on both exact and vicinal Si(001) substrates with a miscut angle of 2° toward Si[1̄10] by reactive deposition epitaxy (RDE) and subsequent molecular beam epitaxy (MBE). On the vicinal Si(001) substrate, the initial BaSi2 nuclei formed by RDE tended to grow unidirectionally with the [010] direction parallel to Si[110] when the annealing temperature of the Si substrate before the growth was increased from 830 to 1000 °C. Transmission electron microscopy showed that the grain size of the BaSi2 films grown by MBE increased up to approximately 9 µm on the vicinal Si(001) substrate when the substrate annealing temperature was 1000 °C. This is the largest grain size ever obtained for BaSi2. Even in the case of the exact Si(001) substrate, the MBE-grown BaSi2 grains preferentially grew with the [010] direction along Si[110] when the annealing temperature was 1000 °C.