High-Throughput Ellipsometric Contrast Microscopy of Lateral 2D Heterostructures for Optoelectronics.

Abstract

Covalently-bonded lateral 2D heterostructures offer unique (opto)electronic functionalities and can be deposited during a single growth process. However, the position of lateral junctions is typically uncontrolled due to random nucleation processes, which necessitates post-growth identification of suitable heterojunction regions for device integration. Here, ellipsometric contrast microscopy (ECM) is demonstrated to evaluate 2D lateral monolayer MoSe₂-WSe₂ and MoS₂-WS₂ heterostructures, which enables rapid imaging with high material-contrast down to sub-nanometer thickness for high-throughput characterisation of heterostructure domains. In addition, a computer vision algorithm provides precise identification of individual monolayer heterostructure junctions and their integration into rectifying devices and photodetectors. These results establish the advantages of ECM for reliable, fast characterization and large-scale integration of atomically thin 2D heterostructures into advanced optoelectronic devices, with potential extension to other nanomaterials.