Unraveling Spatiotemporal Transient Dynamics at the Nanoscale via Wavelet Transform-Based Kelvin Probe Force Microscopy

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

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Abstract

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
Pages (from-to)21506-21517
Number of pages12
JournalACS Nano
Volume17
Issue number21
Early online date25 Oct 2023
DOIs
Publication statusPublished (in print/issue) - 14 Nov 2023

Bibliographical note

Funding Information:
This work is supported by US-Ireland grant with the award number USI 186 (A. F. Payam).

Publisher Copyright:
© 2023 The Authors. Published by American Chemical Society.

Keywords

  • Kelvin probe force microscopy (KPFM)
  • time-resolved KPFM (tr-KPFM)
  • wavelet transforms
  • surface photovoltage
  • transient quantification

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