ABSTRACT
Electrostatic force microscopy (EFM) including its derivative, Kelvin probe force microscopy, is widely used to investigate mesoscopic/nanoscopic conducting/semiconducting structures and electrical interactions. However, the resolution of EFM in ambient is largely limited by the applicable force-detection techniques. This work demonstrates that the lateral resolution of ambient EFM can be significantly improved using an intermittent contact method in conjunction with a resonant multi-frequency method for electrostatic force detection. A lateral resolution of sub-10 nm is obtained. The high-resolution contrast reflects the variation of surface potential in sample on a nanoscale. The mechanism, which is attributed to the decreased effective tip-sample distance, is elucidated by theoretical analysis. The newly developed technique can be easily integrated with existing techniques to herald the next generation of high-resolution probe techniques for various nanoscopic applications.
Funding
The authors acknowledge financial support from National Natural Science Foundation of China under Grant No. 81471787, Guangdong Science and technology project under Grant No. 2014A010104009, and Guangzhou science and technology project under Grant No. 201510010143.