Scale-Dependent Growth Modes of Selective Area Grown III-V Nanowires.

Due to their flexible geometry, in-plane selective area grown (SAG) nanowires (NWs) encompass the advantages of vapor-liquid-solid NWs and planar structures. The complex interplay of growth kinetics and NW dimensions provides new pathways for crystal engineering; however, their growth mechanisms remain poorly understood. We analyze the growth mechanisms of GaAs(Sb) and InGaAs/GaAs(Sb) in-plane SAG NWs using molecular beam epitaxy (MBE). While GaAs(Sb) NWs consistently follow a layer-by-layer growth, the InGaAs/GaAs(Sb) growth transitions from step-flow to layer-by-layer and layer-plus-island depending on the InGaAs thickness and the NW dimensions. We extract the diffusion lengths of Ga adatoms along the [11̅0] and [110] directions under As2 during GaAs(Sb) growth. Our results indicate that Sb may inhibit the layer-by-layer to step-flow transition. Our findings show that different growth modes can be achieved in the MBE of in-plane SAG NWs grown on the same substrate and highlight the importance of the interplay with NW dimensions.