Germanium nanowire synthesis using solid precursors

We report on the synthesis of single crystalline, high aspect ratio germanium (Ge) nanowires (NWs) by vapor transport method using three different solid powder precursors. Investigated precursors were either powder like germanium or powder mixtures like germanium dioxide with carbon and germanium iodide with germanium. As-grown NWs were analyzed using scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-Ray diffraction (XRD) and X-Ray photoelectron spectroscopy (XPS) to obtain structural information. The effect of temperature and pressure on the diameter and morphology of the NWs were determined. Both pressure and temperature were found to increase the diameter of the NWs independent of precursor type. Growth direction of the NWs was found to be the same while clear differences in the morphology and surrounding oxide layer thickness were observed with different precursors. Oxide layer removal via hydrobromic acid treatment was also realized. Results provided in this paper allow the basis for optimizing the synthesis of Ge NWs using solid precursors.