Influence of Water Condensation on Charge Transport and Electric Breakdown Between an Atomic Force Microscope Tip, Polymeric, and (Semiconductor) CdS Surfaces

Abstract

Water condensation is shown to have a major influence on electric charge transport and nanostructure formation in polymer-, and semiconductor-thin-film surfaces in the proximity of a biased Atomic Force Microscope (AFM) tip. The water forms a meniscus bridge between the AFM tip and the surface to form a three-component system comprised of the AFM tip, water meniscus, and the surface. The associated electric field in the meniscus is spatially non-uniform and has a magnitude of the order of 10 8 -10 10 Vm -1 . An intensive experimental analysis of the input and output electric currents in the AFM tip/water meniscus/surface system, performed at various relative humidity levels between 10 and 60%, indicates that the magnitude of the output current, drained from surface, reaches values as large as several μA which exceeds the input current, injected via the AFM tip (0.01-10 nA), by at least an order of magnitude. This effect is particularly evident when the relative humidity is greater than 20-25%, suggesting that the water meniscus is ionized by the strong electric field to produce electrons. Since the method described here for nanopatterning is applicable for materials with significantly different physical, electronic, and optical properties, and is dependent largely on the ambient humidity level and the strength of the electric field, it is suggested that the method may be extended to a variety of other materials.

Tuning Oxygen Vacancy Diffusion through Strain in SrTiO3 Thin Films

“…The thin films were characterized combining electrostatic force microscopy (EFM), and Kelvin probe force microscopy (KPFM). The experiments were performed independently using two different AFM setups, a Park Systems NX10 and a Keysight 5500 AFM under both, ambient and low humidity conditions (6−7% RH), to suppress possible effects derived from charge injection, 27 formation of protons/ hydroxyl radicals, 28 or electrochemical processes. 29 A Pt/Ir-coated metallic tip with a force constant of 3 N/m was used for electrical scans in KPFM and EFM modes.…”

Electric-field-induced band bending on GaN: in situ effects of electron beam irradiation on time-dependent cathodoluminescence

“…8), GaN was purposefully exposed to ambient and immediately irradiated. There is evidence to suggest that water molecules present at the surface of a semiconductor can be ionized in the presence of an electric field, leaving the surface slightly positively charged H 2 O > e − H OH ⋅ [30,42]. As discussed earlier, in HAS, positive surface charge is held by free electrons in n-GaN, which accelerates incoming beam electrons into the interaction volume, inhibiting SE emissions and leading to a dark contrast in SEM [inset Fig.…”

Analysis of beam interference reflected from atomic force microscope tip and periodic silicon surface under various humidity conditions

“…The humidity was monitored by isolating Nanoscope AFM instrument in a closed hood which was supplied by a filtered gas intake [10]. Nitrogen or compressed air was used to supply gases through desiccant filter.…”