Investigation of Sn-containing precursors for in-plane GeSn nanowire growth

Abstract

The formation of Sn catalyst nanoparticles (NPs) for the growth of GeSn nanowires (NWs) requires the identification of suitable Sn-containing precursors. In this work, various Sn-containing precursors such as Sn, SnO2 and indium tin oxide (ITO) thin films as well as SnO2 nanoparticles have been investigated. Sn and SnO2 thin films did not produce NWs. This reveals that the catalyst density, as well as their wetting on the amorphous layer, play vital roles on the growth of GeSn NWs. Conversely, Ge nanocrystals (NCs) were successfully grown from ITO thin films deposited on c-Si substrates. A good crystallinity was obtained when there is no interfacial SiOx layer on the crystalline Si substrate. Finally, using SnO2 NPs allowed us to grow GeSn NWs. Their morphology is strongly impacted by the annealing environment: hydrogen atmosphere with different pressures or hydrogen plasma, the later providing the best results. The nanostructure and composition of GeSn NWs were investigated in detail. These results could pave the way to grow in-plane Ge nanostructures within several types of Sn-containing materials.