Van der Waals heterostructures based on 2D layered materials: Fabrication, characterization, and application in photodetection

Construction of heterostructures has provided a tremendous degree of freedom to integrate, exert, and extend the features of various semiconductors, thereby opening up distinctive opportunities for the upcoming modern optoelectronics. The abundant physical properties and dangling-bond-free interface have enabled 2D layered materials serving as magical “Lego blocks” for building van der Waals heterostructures, which bring about superior contact quality (atomically sharp and distortionless) and the combination of functional units with various merits. Therefore, these heterostructures have been the focus of intensive research in the past decade. This Tutorial begins with a variety of strategies for fabricating van der Waals heterojunctions, categorized into the transfer-stacking method and in situ growth assembly method. Then, the techniques commonly exploited for characterizing the structure, morphology, band alignment, interlayer coupling, and dynamics of photocarriers of van der Waals heterojunctions are summarized, including Raman spectroscopy, photoluminescence spectroscopy, atomic force microscopy, conductive atomic force microscopy, Kelvin probe force microscope, ultraviolet photoelectron spectroscopy, transfer characteristic analysis, scanning photocurrent microscopy, etc. Following that, the application of various van der Waals heterojunctions for diverse photoelectric detection is comprehensively overviewed. On the whole, this Tutorial has epitomized the fabrication, characterization, and photodetection application of van der Waals heterostructures, which aims to provide instructive guidance for the abecedarians in this emerging field and offer impetus of advancing this rapidly evolving domain.