ITO bi-crystal nanowires follow a grain boundary assistant growth mode

Abstract

In this work, indium tin oxide (ITO) bi-crystal nanowires (BCN), that coexist with the normal single crystal ITO nanowires, grown by the e-beam evaporation method are reported. The structure and the growth mechanism of the nanowire were studied by detailed high resolution transmission electron microscopy observations. Different to the conventional twin-structured nanowires that have a definitely defined crystal orientation relationship, ITO BCN were found to be composed of two single crystal nanowires welded with no definite orientation separated by a grain boundary. The detailed nucleation and growth processes of the bi-crystal nanowire were studied and a model based on the grain boundary assistant growth was proposed. It was realized that due to the presence of the grain boundary the two crystals were able to grow along some high indexed crystal directions. This mechanism plays the key role in the formation of special BCN structures.