The delicate interfacial conditions and behaviors play critical roles in determining the valuable physical properties of two-dimensional materials and their heterostructures on substrates. However, directly probing these complex interface conditions remains challenging. Here, we reveal the coupled in-plane strain and out-of-plane bonding conditions in strain-engineered WS2 flakes by combining dual-harmonic electrostatic force microscopy (DH-EFM) and scanning microwave impedance microscopy (sMIM). A striking contradiction is observed between the compressive-strain-induced larger bandgap (lower electrical conductivity) detected by DH-EFM, and the enhanced conductivity probed by sMIM. Comparative measurements under different sMIM modes demonstrate that this contradiction originates from a tip-loading-force-induced dynamic puckering effect, which is governed by the interfacial bonding strength. Furthermore, the progressive accumulation and subsequent release of conductivity during forward/backward sMIM-contact scans further confirms this dynamic puckering behavior, revealing pronounced differences in interface conditions between the open- and closed-ring regions of WS2. This work resolves the correlation between electrical properties and interface conditions, and provides fundamental insights for interface-engineered devices.
@article{arxiv.2510.23139,
title = {Unveiling the delicate "hidden" interface conditions in WS2 flakes by advanced atomic force microscopy},
author = {Yanyan Geng and Chang Li and Shuo Mi and Manyu Wang and Xinen Han and Huiji Hu and Yunzhen Wang and Haojie You and Shumin Meng and Hanxiang Wu and Jianfeng Guo and Shiyu Zhu and Yanjun Li and Yasuhiro Sugawara and Sabir Hussain and Fei Pang and Rui Xu and Zhihai Cheng},
journal= {arXiv preprint arXiv:2510.23139},
year = {2025}
}