Ordered arrays of rare earth silicide nanowires on Si[001]

Abstract

Rare earth silicides have been demonstrated to self-assemble during epitaxial growth as one-dimensional nanostructures with preferred orientation along Si '100' on Si[111] and Si[001]. The evolution of the one-dimensional structure during epitaxial growth has been attributed to an anisotropic lattice mismatch of the two orthogonal axis of the hexagonal unit cell with respect to Si. On highly oriented Si[001] substrates, nanowires align their long axis along '100' Si: thus, two orientations of nanowires were obtained having their long axes orthogonal to one another. We have now demonstrated that alignment of rare earth silicide nanowires can be achieved along a single direction by growth on vicinal Si[001] substrates. Self-assembled ErSi2 and DySi2 wires aligned along Si [110] have been grown at 600°C with aspect ratios exceeding 100 and feature heights on the order of 1 atomic layer. The nanowires were characterized in situ with scanning tunneling microscopy. These rare earth silicide nanowires may have applications as non-lithographically fabricated small scale interconnects due to high electrical conductivity and low Schottky barrier to n-type Si.