Fabrication and characterization of MOS2/WS2 van der waal’s heterostructure

Abstract

Ultrathin graphene-like two-dimensional (2D) transition-metal dichalcogenides (TMDCs) due to their fundamentally intriguing properties have attracted a wide range of research interest in recent days. Combining different materials to obtain the elite properties of each compound and tuning them according to the prerequisite has been the grounds for the successful fabrication of a number of novel devices. In such a manner, various 2D materials can be brought together to concoct new devices for a broad range of applications. MoS2 and WS2 are two such TMDCs with excellent electronic and optical properties. Since these are atomically thin layered materials and are held by a weak van der Waals force, it is easier to peel them apart to form thin sheets, and hence the combined arrangement of different materials is named as van der Waals heterostructure. Our motive here is to make use of the mechanical exfoliation technique, which has the ability to yield a pure highly crystalline atomically thin layer of TMDCs (MoS2 and WS2). These layers are then stacked one above the other to form van der Waals heterostructure, whose fundamental properties are then studied in detail. The morphological and topographical properties are investigated from the data obtained from several microscopic techniques. Its optical and vibrational properties are scrutinized from various spectroscopic techniques. The data we acquired from optical imaging and Raman scattering, gives an insight into the thickness and edge effects of the flake. The absorption spectrum of MoS2, WS2, and their heterostructure reveal several interesting properties of the electronic band structure. These properties can then be explored and incorporated practically in several fields to fabricate energy storage devices, flexible and transparent electronics, thin electronics, switching devices, photodetectors, etc.