Optimized Ge nanowire arrays on Si by modified surfactant mediated epitaxy

Abstract

We demonstrate the formation of Ge nanowire arrays on highly ordered kink-free Si stepped surfaces. The nanowires are grown using Bi surfactant mediated epitaxy. The nanowires are single crystalline and feature minimal kink densities, allowing them to span lengths larger than $1\phantom{\rule{0.3em}{0ex}}\ensuremath{\mu}\mathrm{m}$ at a width of $\ensuremath{\approx}4\phantom{\rule{0.3em}{0ex}}\mathrm{nm}$. To achieve desired growth conditions for the formation of such nanowire arrays, we explore a full parameter space of surfactant mediated epitaxy. We show that controlling the surfactant coverage in the surface and/or at step edges modifies the growth properties of surface steps in a decisive way.