Spectroscopic photoemission and low-energy electron microscopy studies of the surface and electronic structure of two-dimensional materials

Abstract

Advances in two-dimensional (2D) materials research have opened up new opportunities in miniaturization of optoelectronic and spintronic devices at the atomically thin limit. One major research thrust, which is the subject of this review, is the surface-and electronic structure of 2D materials and their van der Waals (vdW) heterostructures that may be significantly affected by the local atomic geometry and environment. As a result, there is a pressing need for powerful advanced microscopy and spectroscopy techniques for material characterization at a micro-or sub-micrometer lateral scale, which is a typical sample size in many 2D-materials experiments. Spectroscopic photoemission and low-energy electron microscopy (SPE-LEEM) offer a multifunctional approach that uniquely integrates microscopy, diffraction and spectroscopy techniques, enables real-time imaging and in situ structural, chemical and electronic analysis of surfaces and interfaces. This review covers the recent developments in SPE-LEEM investigations of surface-and electronic structure of 2D materials, and presents examples including exfoliated vdW layered materials, vdW heterostructures, and thin films synthesized by chemical vapor deposition and molecular beam epitaxy.

Ultrafast Photoemission Electron Microscopy: Imaging Plasmons in Space and Time

“…A more element specific method relies on the excitation of the core states of atoms with a defined charge to obtain element tagged, nanoscale imaging of complex materials. This has been particularly useful for studies of complex catalytic surfaces, two-dimensional materials and magnetic materials. ,, Magnetic materials also gain further contrast mechanism by employing magnetic circular and linear dichroism, or electron spin-resolved imaging, to image ferromagnetic , and/or antiferromagnetic domains in materials with complex magnetization. Thus, an astute choice of light-matter interaction and photoelectron analysis enables nanoscale imaging of complex chemical and physical phenomena.…”

Atomic Precision Processing of Two-Dimensional Materials for Next-Generation Microelectronics

“…These inherent requirements of process monitoring are crucial issues of metrology for semiconductor manufacturing in general. There are well-established in-lab technologies offering high sensitivity and atomic resolution for 2D materials, such as X-ray photoemission electron microscopy (XPEEM), 29 scanning tunneling microscopy (STM), 30,31 and atom probe tomography, 32,33 to name a few. However, the increasing demands for high-throughput and scalable characterization make metrology during APP of 2D materials challenging.…”