(Invited) Interfacial Engineering of Two-Dimensional Nanomaterials: Chemical Functionalization and Scanning Probe Characterization

Abstract

Atomically thin two-dimensional (2D) materials have recently emerged as promising materials for electronic and photonic devices due to their unique layer-number-dependent properties. Because they are atomically thin, interfacial interactions between 2D materials and their surroundings play an important role in regulating their properties for device applications. The electronic and optical properties of 2D materials can be readily engineered by covalent and non-covalent chemical functionalization methods, and can be characterized with atomic-scale precision using scanning probe microscopies. In this work, we demonstrate the functionalization of MoS2 and WSe2 by covalent and non-covalent chemistries, which result in charge transfer, layer-dependent reactivities, and molecular rearrangements at their surfaces. We characterize the structural, electronic, and optical changes to the 2D materials using ultrahigh vacuum scanning tunneling microscopy (UHV STM), atomic force microscopy (AFM), and Raman and photoluminscence (PL) spectroscopic mapping. By controlling the chemical groups that are used in the functionalization reactions, we can engineer their effect on the interfacial properties of 2D materials, which will be important to the processing of novel electronic and photonic devices.