Citation Link: https://doi.org/10.1088/1361-6528/ad2156
Transition from fractal-dendritic to compact islands for the 2D-ferroelectric SnSe on graphene/Ir(111)
Publication Type
Article
Subjects
Materials science
Scanning tunneling microscope
Monolayer
Annealing (glass)
Epitaxy
Condensed matter physics
Molecular beam epitaxy
Superlattice
van der Waals force
Ferroelectricity
Chemical physics
Nanotechnology
Crystallography
Optoelectronics
Dielectric
Layer (electronics)
Molecule
Date Issued
2024
Abstract
Epitaxial growth is a versatile method to prepare two-dimensional van der Waals ferroelectrics like group IV monochalcogenides which have potential for novel electronic devices and sensors. We systematically study SnSe monolayer islands grown by molecular beam epitaxy, especially the effect of annealing temperature on shape and morphology of the edges. Characterization of the samples by scanning tunneling microscopy reveals that the shape of the islands changes from fractal-dendritic after deposition at room temperature to a compact rhombic shape through annealing, but ripening processes are absent up to the desorption temperature. A two-step growth process leads to large, epitaxially aligned rhombic islands bounded by well-defined $\left\langle 110\right\rangle $ -edges (armchair-like), which we claim to be the equilibrium shape of the stoichiometric SnSe monolayer islands. The relaxation of the energetically favorable edges is detected in atomically resolved STM images. The experimental findings are supported by the results of our first-principles calculations, which provide insights into the energetics of the edges, their reconstructions, and yields the equilibrium shapes of the islands which are in good agreement with the experiment.
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