Experimental setup, technique validation: (a) tip trajectory during one SS-KPFM scan; (b) SS-KPFM raw data of a WS2
flake on p-doped Si at 0.25 fps. Inset - raster scan heterodyne-(H)-KPFM acquired from same flake at 0.000065 fps; (c) reconstructed image using Gaussian process; (d) Profiles of raster scan H-KPFM vs SS-KPFM.
flake on p-doped Si at 0.25 fps. Inset - raster scan heterodyne-(H)-KPFM acquired from same flake at 0.000065 fps; (c) reconstructed image using Gaussian process; (d) Profiles of raster scan H-KPFM vs SS-KPFM.
Scientific Achievement
A novel atomic force microscope (AFM) method was developed to quantify localized ionic transport in oxide materials. Visualization of local surface electrochemistry was enabled in LaAlO3/SrTiO3 devices and the role of temperature in oxygen vacancy diffusion in TiO2 was achieved.
Significance and Impact
Few current techniques can spatially discern ionic transport at small scales. Our research paves the way for rapid charge mapping via smart scanning probe methods, with potential impacts in energy materials, photovoltaics, and nano-electrochemistry.
Research Details
- By combining fast sparse scanning and image reconstruction algorithms, we achieved a remarkable 3 orders of magnitude increase in the speed of functional AFM imaging.
- Local water-mediated surface electrochemistry was mapped in LaAlO3/SrTiO3 devices and correlated with macroscopic measurements.
- Diffusion of oxygen vacancies in TiO2 at various temperatures was mapped, deriving the activation energy for the process, which was supported by molecular dynamics simulations.
M. Checa, et al., Nature Communications 14, 7196 (2023)
DOI: 10.1038/s41467-023-42583-x
Work was conducted at the Center for Nanophase Materials Sciences
