UC Irvine

Ordered arrays of self-assembled ErSi2-x, SmSi2-x, DySi2-x and HoSi2-x nanowires aligned along Si[110] have been grown at 600°C on Si(001) vicinal substrates with wire widths on the order of a nanometer and lengths exceeding 1 micron. The nanowires were characterized in situ with scanning tunneling microscopy and ex situ with atomic force microscopy. The length of coherently strained nanowires is dependent on surface kinetics while the wire width is thermodynamically controlled via strain energy. The unit cell of these rare earth disilicides is non-cubic and has an asymmetric lattice mismatch with the cubic unit cell of Si. The nanowire width decreases monotonically with increasing lattice mismatch between the Si [1~10] and RSi2-x [0001] lattice constants. Therefore, nanowire width may be varied by tuning the RSi2-x lattice constant along [0001] via fabrication of a ternary disilicide. In addition, the crystal quality of the nanowires may be improved by minimizing the lattice mismatch along the wire axis. We have grown (Er1-yHoy)Si2-x and (Er1-yDyy)Si2-x nanowires on Si(001) and analyzed the microstructure to investigate ternary disilicide growth.