Abstract
The vapor–liquid–solid growth of III-V nanowires proceeds via the mononuclear regime, where only one island nucleates in each nanowire monolayer. The expansion of the monolayer is governed by the surface energetics depending on the monolayer size. Here, we study theoretically the role of surface energy in determining the monolayer morphology at a given coverage. The optimal monolayer configuration is obtained by minimizing the surface energy at different coverages for a set of energetic constants relevant for GaAs nanowires. In contrast to what has been assumed so far in the growth modeling of III-V nanowires, we find that the monolayer expansion may not be a continuous process. Rather, some portions of the already formed monolayer may dissolve on one of its sides, with simultaneous growth proceeding on the other side. These results are important for fundamental understanding of vapor–liquid–solid growth at the atomic level and have potential impacts on the statistics within the nanowire ensembles, crystal phase, and doping properties of III-V nanowires.
Highlights
Nucleation and growth of NW MLs is fundamentally important as it determines the crystal phase of III-V NWs [5,6], composition of ternary III-V NWs [7,8], and influences the NW doping process [9]
We show the significant impact of small variations in the surface energies on the ML morphology throughout its growth cycle
To calculate the surface energy term of the ML formation energy, ∆GS, we consider nucleation at the TPL, which is necessary for the occurrence of the WZ crystal phase in III-V NWs [6]
Summary
To calculate the surface energy term of the ML formation energy, ∆GS , we consider nucleation at the TPL, which is necessary for the occurrence of the WZ crystal phase in III-V NWs [6] In this case, the island (fractional ML) edge at the TPL is formed by adding the vapor–solid (VS) interface with the surface energy γVS hL1010 and eliminating the vapor–liquid (VL). The total change of the surface energy upon forming a fractional ML is given by The hexagonal top facet of the NW is represented by a regular triangular mesh with spacing between the neighboring l+=γ41010 an of 1120 radius R = 20 nm, this(1). For a given θ , P are all the representative polygons at different θ gives the dynamics of ML growth based on computed and compared, resulting in the energetically preferred P extracted for each the surface energy minimization.
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