Validating the Use of Conductive Atomic Force Microscopy for Defect Quantification in 2D Materials

Defects significantly affect the electronic, chemical, mechanical, and optical properties of two-dimensional (2D) materials. Thus, it is critical to develop a method for convenient and reliable defect quantification. Scanning transmission electron microscopy (STEM) and scanning tunneling microscopy (STM) possess the required atomic resolution but have practical disadvantages. Here, we benchmark conductive atomic force microscopy (CAFM) by a direct comparison with STM in the characterization of transition metal dichalcogenides (TMDs). The results conclusively demonstrate that CAFM and STM image identical defects, giving results that are equivalent both qualitatively (defect appearance) and quantitatively (defect density). Further, we confirm that CAFM can achieve single-atom resolution, similar to that of STM, on both bulk and monolayer samples. The validation of CAFM as a facile and accurate tool for defect quantification provides a routine and reliable measurement that can complement other standard characterization techniques.