Nanoscale Electrical Mapping of Two-dimensional Materials by Conductive Atomic Force Microscopy for Transistors Applications

Two-dimensional (2D) materials are currently object of many interests both from a basic and a technological standpoint. In particular, graphene (Gr) and the semiconducting transition metal dichalcogenides (including MoS2, WS2, MoSe2, WSe2) have been widely investigated for transistors applications. As a matter of fact, 2D materials present peculiar nanoscale structural and electrical inhomogeneities, related to the specific synthesis mechanisms and to the interaction with the substrate. which are ultimately reflected in the macroscopic electrical behaviour of electronic devices based on these systems. In this context, conductive atomic force microscopy (CAFM) is the method of choice to investigate the mechanisms of current injection between contacts and 2D materials and/or the lateral homogeneity of 2D materials electrical properties. This paper will discuss some case studies of CAFM applications to Or and MoS2, to illustrate the potentiality of this characterization method for 2D materials investigation. The results of these nanoscale analyses will be used to explain the electrical behaviour of field effect transistors fabricated on these materials.