In Situ Manipulation of Growth Mechanisms in the Vapor–Solid–Solid Growth of GaP Nanowires

Vapor–solid–solid (VSS) growth of III-V semiconductor nanowires (NWs) has long been considered an alternative for the vapor–liquid–solid (VLS) growth mode, with the potential to avoid the incorporation of deep-level impurities into semiconductors and to form compositionally abrupt interfaces. Most research however indicates that VSS growth has a much lower growth rate than observed in the VLS growth regime, explained by the very slow mass transport at the solid seed particle-NW interface. In this study, the direct observation of the VSS growth of GaP NWs under different mechanisms is reported, by using Ni as a seed material inside an environmental transmission electron microscope. These results reveal that when NWs are grown from seed particles exhibiting the NiGa and Ni₂Ga₃ phases, classic VSS growth occurs with slow NW growth and interface diffusion as the dominant mass transport pathway. In contrast, when NWs are grown by seed particles containing Ni₂P phase, rapid NW growth is observed together with a continuous reshaping of the seed particle. A cation exchange reaction is proposed as the predominant growth mechanism. This research results demonstrate an entirely new variant of the VSS growth mode, opening up new degrees of freedom for tuning NW properties.