Insight into the vacancy behaviour at the interface of As-Sb lateral heterostructure
Using detailed first-principles calculations, we investigate the behaviour of interface vacancies in the lateral heterostructure (LHS) constructed by arsenene (As) and antimonene (Sb), which is demonstrated to have many unique properties but with large lattice mismatch [Sun et al., 2D Mater., 2016, 3, 035017]. Our calculated results show that the energetic, kinetic, and electronic properties of atomic vacancies are greatly modified at the interface of As-Sb LHS. Two mechanisms are demonstrated to govern the migration of interface DV-585s based on the dissociation/recombination of SVs and the exchange of atoms adjacent to the vacant sites, respectively. DV-5-585 is identified to be the lowest-energy atomic vacancy at the interface. The easy formation of DV-5-585 resulted from the release of the compressed stress in the Sb block suggests that, in highly mismatched LHSs, much attention should be paid to the potentially large concentration of detrimental interface vacancies close to the compressed building blocks where the proper selection of temperature and careful control of atomic chemical potential are essential. Meanwhile the unexpected half-metal states induced by DV-3-585-o and DV-4-585-o rooted in the unpaired As atoms driven by the tensile stress enlightens that decorating atomic vacancies in the stretched building blocks may provide an effective way to achieve the functionalization of LHSs with large lattice mismatch. In addition, we reveal a single-atom-triggered transition between metal and semiconductor in SV-As-1 decorated As-Sb LHS. Thus, by manipulating the Sb atom at the interface, defect of SV-As-1 may be used as the atomic switch to control the on-off states of circuit at the nanoscale, making As-Sb LHS promising candidate for application in nanoelectronic devices. Our theoretical work enriches the fundamental understanding of intrinsic defects at the interface of As-Sb LHSs, and provides significant insight towards the defect and interface engineering in the LHSs with large lattice mismatch, which are of great relevance to the manipulation of the LHS properties for the design of novel nanodevices.