High-speed mapping of surface charge dynamics using sparse scanning Kelvin probe force microscopy.

Area of Science:

• Materials Science
• Surface Science
• Physical Chemistry

Background:

• Understanding local dynamic charge processes is crucial for microelectronics and energy storage.
• Mapping charge carrier motion across multiple length and timescales is essential.
• Material heterogeneities significantly influence charge dynamics.

Purpose of the Study:

• To introduce a novel high-speed sparse scanning Kelvin probe force microscopy technique.
• To enable sub-second imaging of nanoscale charge dynamics.
• To visualize and quantify ionic charge carrier motion in material systems.

Main Methods:

• High-speed sparse scanning Kelvin probe force microscopy (KPFM) with image reconstruction.
• Sub-second imaging (over 3 frames per second) of nanoscale charge dynamics.
• Integration with macroscale device measurements.

Main Results:

• Visualized electrochemically mediated diffusion of mobile surface ions on LaAlO3/SrTiO3 devices.
• Monitored oxygen vacancy diffusion at the single grain level in polycrystalline TiO2.
• Determined a charge diffusion activation energy of 0.18 eV for TiO2, confirmed by DFT calculations.

Conclusions:

• The developed high-speed KPFM technique significantly improves imaging rates for nanoscale charge dynamics.
• The method effectively visualizes ionic charge carrier motion, impacting understanding of heterointerfaces and material properties.
• This versatile technique offers new possibilities for studying charge transport in microelectronics and nanoscale systems.