Unravelling spatio-temporal transient dynamics at nanoscale via wavelet transform-based Kelvin probe force microscopy

Pardis Biglarbeigi, Alessio Morelli, Serene Pauly, Zidong Yu, Wenjun Jiang, Surbhi Sharma, Dewar D. Finlay, Amit Kumar, Navneet Soin, Amir Farokh-Payam

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Mechanistic probing of surface potential changes arising from dynamic charge transport is the key to understanding and engineering increasingly complex nanoscale materials and devices. Spatiotemporal averaging in conventional heterodyne detection-based Kelvin probe force microscopy (KPFM) inherently limits its time resolution, causing an irretrievable loss of transient response and higher-order harmonics. Addressing this, we report a wavelet transform (WT)-based methodology capable of quantifying the sub-ms charge dynamics and probing the elusive transient response. The feedback-free, open-loop wavelet transform KPFM (OL-WT-KPFM) technique harnesses the WT’s ability to simultaneously extract spatial and temporal information from the photodetector signal to provide a dynamic mapping of surface potential, capacitance gradient, and dielectric constant at a temporal resolution 3 orders of magnitude higher than the lock-in time constant. We further demonstrate the method’s applicability to explore the surface-photovoltage-induced sub-ms hole-diffusion transient in bismuth oxyiodide semiconductor. The OL-WT-KPFM concept is readily applicable to commercial systems and can provide the underlying basis for the real-time analysis of transient electronic and electrochemical properties.
Original languageEnglish
JournalACS Nano
Early online date25 Oct 2023
Publication statusEarly online date - 25 Oct 2023


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