Molecular beam epitaxial growth and scanning tunneling microscopy characterization and manipulation of monolayers and heterostructures of two-dimensional ferroelectrics

Abstract

2D ferroelectric materials have become an important subset belonging to 2D materials due to their potential applications. In this thesis, I report work on molecular beam epitaxial (MBE) synthesis of monochalcogenide lateral heterostructures (LHSs), characterization and manipulation by scanning tunneling microscopy (STM). First, I present MBE growth of monolayer PbTe/SnTe LHSs. An asymmetric diffusion at the interfaces and a model of the diffusion mechanism had been discovered and developed. Second, I introduce the discovery of vortex-oriented ferroelectric domains in monolayer PbTe /SnTe LHSs, which are a result of ferroelectricity, charge transfer, and interfacial strain. Lastly, I present work on realization of defect-free nano-welding of SnSe nanoplates by an anisotropic friction and in-situ annealing in the VT-STM. Our results in this thesis are a major step towards the construction of nanostructures from diverse 2D materials.