Electron-Beam Excited Conductive Atomic Force Microscopy for Back Contact Free, Wafer-Scale and In-Line Compatible Electrical Characterization of 2D Materials.

Electrical atomic force microscopies (AFMs) have emerged as leading metrology techniques for evaluating the quality of 2D materials. Their advantages include high-resolution electrical mapping, non-destructive measurement, and the ability to probe nanoscale defects and transport properties. Conductive AFM (C-AFM) has been particularly instrumental, enabling the direct observation of individual vacancies and vacancy clusters, voids, wrinkles, and cracks. Despite this incredible versatility, C-AFM remains a two-probes method, thus it is limited by the need for physical back-contact. Creating this back contact is complex and time-consuming. More importantly, this requirement prevents C-AFM from being a viable in-line metrology technique. Here, it is demonstrated that a low-energy e-beam impinging on the sample surface can be used to perform C-AFM, in a new configuration that is electron-beam (e-beam) excited conductive atomic force microscopy (EBC-AFM). This approach enables comparable results to classic C-AFM sensitivity, while unlocking applications that were not previously possible. After introducing the experimental setup, the main parameters associated with the e-beam and their impact on the C-AFM measurement are studied. Finally, using several 2D materials as testbeds, the competitive electrical mapping capabilities of EBC-AFM for defect assessment are demonstrated. Furthermore, this technique overcomes limitations for studying isolated flakes and enables wafer-scale characterization of 2D materials.