For self-catalyzed nanowires (NWs), reports on how the
catalytic
droplet initiates successful NW growth are still lacking, making it
difficult to control the yield and often accompanying a high density
of clusters. Here, we have performed a systematic study on this issue,
which reveals that the effective V/III ratio at the initial growth
stage is a critical factor that governs the NW growth yield. To initiate
NW growth, the ratio should be high enough to allow the nucleation
to extend to the entire contact area between the droplet and substrate,
which can elevate the droplet off of the substrate, but it should
not be too high in order to keep the droplet. This study also reveals
that the cluster growth between NWs is also initiated from large droplets.
This study provides a new angle from the growth condition to explain
the cluster formation mechanism, which can guide high-yield NW growth.