Metal silicides bear potential for a wide range of application in microelectronics and photovoltaics due to their excellent electro-physical properties such as high optical absorption, low resistivity and compatibility with silicon-based semiconductor processes. Controlling the morphology of such metal silicide crystals thus represents a promising approach for microelectronic bottom-up device fabrication. In the last decade, the growth of iron and cobalt silicide nanowires has been targeted by means of single- or two-source chemical vapour transport (CVT). However, the lack of a comprehensive mechanistic understanding of the nanowire growth hinders further development of metal silicides towards sophisticated systems [1].

To reveal aspects of the mechanism involved in the nanowire formation, we studied the CVT reactions of all chemical species in the systems. Experimental results were compared to thermodynamic predictions calculated by means of the Gmin-method. These findings were applied to the single-source CVT growth of nanowires. This allowed to assess the thermodynamic framework of the reaction leading to nanowire formation. Single-source CVT on silicide substrates was coupled to a subsequent CVT on sapphires substrates. This enabled the precise determination of growth parameters influencing the chemical reaction that leads to the formation of nanostructures. By varying these parameters, the growth of nanowires could either be induced on the silicon substrates or the downstream placed sapphire. These findings indicate that nanostructured growth is accessible entirely by conventional CVTs, allowing for a transition of growth morphology during the process. In conclusion, this offers potential opportunities to fine-tune metal silicides for applications in electronic and photovoltaic devices.

References
[1] Y, Huang, K.N. Tu (2016): Silicon and silicide nanowires, fabrication and properties. 1st edition: Jenny Stanford Publishing.