Published online by Cambridge University Press: 03 October 2011
The direct integration of Ge nanowires with silicon is of interest in multiple applications. In this work, we describe the growth of high-quality, vertically oriented Ge nanowires on Si (111) substrates utilizing a completely sub-Au–Si-eutectic annealing and growth procedure. With all other conditions remaining identical, annealing below the Au–Si eutectic results in successful heteroepitaxial nucleation and growth of Ge nanowires on Si substrate while annealing above the Au–Si eutectic leads to randomly oriented growth. A model is presented to elucidate the effect of the annealing temperature, in which we hypothesized that sub-Au–Si-eutectic annealing leads to the formation of a single and well-oriented interface, essential to template heteroepitaxial nucleation. These results are critically dependent on substrate preparation and lead to the creation of integrated nanowire systems with a low thermal budget process.
Figure S1: SEM images of Ge nanowires grown on the SiO2 surface, with annealing at 320 °C (a) and 400 °C (b). SEM images were taken with a 25° inclination from the plan-view (in a, b and c) and in cross-sectional view (insets to a, b and c). All scale bars are 1 μm.