Slow Charge Dynamics at 2D Material/Dielectric Interfaces Revealed by Multimodal Microscopy

Charge trapping and slow decay dynamics at 2D material-dielectric interfaces limit the performance and stability of nanoelectronics. However, the physical pathways remain elusive, hindered by difficulties in tracking nanoscale charge evolution over long times and the intricate interplay of intrinsic and extrinsic effects. Here, we introduce a multimodal microscopy platform integrating conductive atomic force microscopy for charge injection, time-resolved Kelvin probe force microscopy for potential tracking, and correlated spectroscopy to probe WS₂/SiO₂ and graphene/SiO₂ interfaces. We discover that WS₂ shows a triple-exponential decay, while graphene exhibits a double-exponential decay, linking complexity to intrinsic properties. We identify three decay channels: universal environmental neutralization; a material-specific, polarity-dependent path via intrinsic defects (unique to WS₂); and a universal, polarity-dependent path via substrate traps. Guided by this model, we demonstrate that hexagonal boron nitride encapsulation suppresses extrinsic channels, achieving quasi-nonvolatile charge retention exceeding 17 days. This framework provides a roadmap for designing stable 2D nanoelectronics.