Nondestructive Atomic Defect Quantification of Two-Dimensional Materials and Devices

Rapid and quantitative characterization of atomic defects in two-dimensional (2D) semiconductors and transistors is crucial for growth optimization and understanding of device behavior. However, such defect metrology remains challenging due to limitations of existing characterization methods, which are generally destructive and slow or lack the necessary sensitivity. Here, we use nondestructive lateral force microscopy (LFM) to directly map surface defects in monolayer WSe2 and WS2 on different growth substrates (SiO2 and sapphire), as well as in WSe2 transistors. Through LFM measurements on various WSe2 layers, we show that this technique can detect defect densities well below the range of typical Raman measurements on this material. We also demonstrate mapping of spatial variation of defect density within as-grown WSe2 and that the LFM technique can detect defects on suspended and polymer-supported monolayers, expanding the application space. Applied to WSe2 transistors, LFM uncovers defect densities over double that of similar as-grown films, suggesting that defects can be introduced by common fabrication processes. This work demonstrates the applications of LFM as a nondestructive defect characterization method for monitoring 2D material growth and device fabrication.