Multitask Scanning Probe Microscopy
This work addresses the challenge of efficiently distributing diverse nanoscale measurements across large spatial domains for materials scientists, particularly when different modalities have varying acquisition times and potential for damage.
The paper introduces multitask scanning probe microscopy, a closed-loop workflow that uses a multitask Gaussian process to autonomously select both measurement locations and experimental protocols. This method was demonstrated on an AlScN wafer using tapping-mode and Dual AC Resonance Tracking measurements, enabling efficient distribution of measurements across large spatial domains.
Scanning probe microscopy provides nanoscale access to structural, electrical, electromechanical, magnetic, and mechanical properties of materials. Its increasing use for wafer-scale characterization and combinatorial materials exploration creates a need to distribute measurements efficiently across large spatial domains. This is particularly important when available modalities differ in acquisition time and potential for tip and sample damage, making exhaustive multimodal mapping over spatial grids impractical. Here, we demonstrate multitask scanning probe microscopy, a live, closed-loop workflow in which a multitask Gaussian process learns spatial and cross-modal relationships and autonomously selects both the next measurement location and the next experimental protocol. The approach is implemented on an automated large-sample atomic force microscope and demonstrated on a composition-spread AlScN wafer using tapping-mode and Dual AC Resonance Tracking (DART) measurements. Paired initial measurements establish the relation between the tasks, after which noncoincident measurements are used to update both response landscapes. The resulting workflow extends active learning in scanning probe microscopy from spatial sampling to autonomous allocation of measurement modalities and provides a basis for combining rapid, weakly perturbative imaging with slower contact, electrical, electromechanical, magnetic, or spectroscopic measurements.