Controlled Growth and Structures of Molecular-Scale Silicon Nanowires

TLDR

The authors synthesized single‑crystal silicon nanowires down to 3 nm using gold nanocluster‑catalyzed 1D growth with silane in hydrogen, and employed cross‑sectional TEM to probe how surface energetics dictate growth direction. High‑resolution TEM revealed that silicon nanowires as small as 3 nm are single‑crystalline with negligible oxide, with the smallest wires growing along <110> and larger ones along <111>, demonstrating that well‑defined molecular‑scale single‑crystal wires can be produced for future fundamental studies and nanodevice applications.

Abstract

Single-crystal silicon nanowires with diameters approaching molecular dimensions were synthesized using gold nanocluster-catalyzed 1D growth. High-resolution transmission electron microscopy studies show that silicon nanowires grown with silane reactant in hydrogen are single crystal with little or no visible amorphous oxide down to diameters as small as 3 nm. Structural characterization of a large number of samples shows that the smallest-diameter nanowires grow primarily along the 〈110〉 direction, whereas larger nanowires grow along the 〈111〉 direction. In addition, cross-sectional transmission electron microscopy was used to address the importance of surface energetics in determining the growth direction of the smallest nanowires. The ability to prepare well-defined molecular-scale single-crystal silicon nanowires opens up new opportunities for both fundamental studies and nanodevice applications.