Self-assembled Ge nanowires grown on Si(113)

We grew coherent Ge islands on Si(113) substrates by molecular beam epitaxy. Atomic force microscopy and reflection high energy electron diffraction were used to examine surface morphology as a function of Ge coverage and growth temperature. The as-grown coherent islands were shaped like wires and formed dense arrays over the entire surface. The islands bounded by {519} facets were elongated in the [33(2) over bar] direction and were linearly ordered across steps. The wire-shaped islands formed when Ge coverage was 5-8 monolayers and the growth temperature was 400-500 degrees C. Cross-sectional transmission electron microscope images confirm that the Ge islands are coherently grown on the Si substrates. The anisotropic shape of the Ge islands was due to an anisotropic strain relief mechanism on Si(113), which had been theoretically predicted. Our findings suggest that the coherent island formation of Ge on Si(113) may be a possible method to fabricate self-assembled Ge nanowires. (C) 1997 American Institute of Physics.