Engineering the Growth of Germanium Nanowires by Tuning the Supersaturation of Au/Ge Binary Alloy Catalysts

Abstract

The synthesis of Ge nanowires with very high-aspect ratios (greater than 1000) and uniform crystal growth directions is highly desirable, not only for investigating the fundamental properties of nanoscale materials but also for fabricating integrated functional nanodevices. In this article, we present a unique approach for manipulating the supersaturation, and thus the growth kinetics, of Ge nanowires using Au/Ge bilayer films. Ge nanowires were synthesized on substrates consisting of two parts: a Au film on one-half of a Si substrate and a Au/Ge bilayer film on the other half of the substrate. Upon annealing the substrate, Au and Au/Ge binary alloy catalysts were formed on both the Au and Au/Ge-sides of the substrates, respectively, under identical conditions. The mean lengths of Ge nanowires produced were found to be significantly longer on the Au/Ge bilayer side of the substrate compared to the Au-coated side, as a result of a reduced incubation time for nucleation on the bilayer side. The mean length ...