Growth of bulk functionalized silicon nanowires: importance of the gaseous phase

International audience; Silicon nanowires (SiNWs) have remarkable properties allowing new applications. Forexample, Li-ion batteries performances can be significantly improved[1]. It is therefore interesting toproduce them in an easy and quantitative way, and our team recently patented a new innovative growthprocess in this way. It allows high yield and bulk production of SiNWs, thanks to a non-dangerousorganosilane precursor, a gold nanoparticle catalyst, and a sacrificial support in NaCl[2]. The assynthetized SiNWs are surface functionalized, which is very useful for making SiNWs/carboncomposites. With this new process, the SiNWs diameter is always close to 10 nm with a sharpdistribution; the reason is not clear. In the present work we focus on the reaction mechanism, with theaim to understand the size limitation and the way the functionalization is happening. Electronicmicroscopy on SiNWs after a short reaction time revealed that 2 distinct populations of SiNWs withdifferent diameters (6nm and 10nm) are formed separately at different reaction times. Also, by usingNMR spectroscopy and a scavenger, we show that silylenes are part of the process as reactionintermediates. The gaseous phase plays for sure a key role in the mechanism, and the understandingof the steps occurring there is fundamental for the tunability of the SiNWs.1. Chan C.K., Peng H., Liu G. McIlwrath K., Zhang X.F., Huggins R.A. and Cui Y., Nature Nano., 2008, 3, 31-342. Chenevier P., Reiss P., Burchak O., Method for Producing Silicon Nanowires, FR3022234 (A1), 2015