Electrical discharge in a nanometer-sized air/water gap observed by atomic force microscopy.
We report a method to initiate and investigate electrical discharges of ambient air/water molecules in a nanometer-sized gap. Our methodology is based on a typical atomic force microscopy (AFM) setup, in which a cylinder discharge gap of < or =5 nm could be configured between the AFM probe and substrate. We observed highly localized stochastic nanoexplosions in which the discharge probability is dominated by the electric field, material-specific surface reactions, and humidity. AFM results, coupled with the boundary element method (BEM), finite element method (FEM), and method of characteristics (MOC) simulations, further revealed the generation of transient shock waves in the nanoscale discharge. The propagation of shock fronts significantly facilitates the radial expansion of the ionized particles, leading to the formation of microscale patterns on selected substrates. Our findings provide an initial understanding of nanoscale discharge and could be relevant to a few applications including nano/microstructuring, microelectronics, and plasma-assisted depositions.
Xie
Xian Ning
XN
NUS Nanoscience and Nanotechnology Initiative (NUSNNI), and Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore 117542. nnixxn@nus.edu.sg
Chung
Hong Jing
HJ
Sow
Chorng Haur
CH
Adamiak
Kazimierz
K
Wee
Andrew Thye Shen
AT