Multi-Probe Scanning Tunneling Microscopy Techniques

Over the past decade, multiprobe scanning tunneling microscopy has emerged as a vital tool for nanoscale electrical characterisation, enabling direct interrogation of local conductivity, electronic structure and interconnectivity in low-dimensional systems. By deploying two or more tips onto a surface, researchers can perform four‐point measurements, probe potential landscapes and investigate transport phenomena beyond the capabilities of single‐tip STM. Key challenges include achieving stable tip–sample junctions at atomic precision, maintaining consistent probe spacing below 50 nm and integrating versatile tip geometries with existing instruments. Innovations in microfabrication, feedback control and on‐chip designs have addressed these hurdles, offering unprecedented access to correlated measurements of atomic wires, surface reconstructions and mesoscopic circuits. Such platforms deepen understanding of fundamental transport mechanisms and pave the way for custom multi‐tip architectures in next‐generation electronic and spintronic devices.

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Research from all publishers

Recent advances in device integration have been demonstrated by the fabrication of lithographically defined on‐chip double‐tip assemblies. Gold tips separated by approximately 35 nm on a silicon nitride substrate have enabled stable, fixed arrangements of probes for high‐resolution concurrent measurements on a single sample surface. Atomically precise two‐probe experiments have extended conventional single‐tip capabilities by employing dual scanners that approach a dangling‐bond wire on a hydrogenated semiconductor surface, achieving probe separations down to 30 nm. This configuration allowed direct measurement of I–V characteristics along a 70 nm atomic wire, opening new avenues in nanoscale circuit characterisation. Concurrently, refined approaches to probe preparation have targeted tip rigidity and spacing. Focused ion beam milling of electrochemically etched tungsten tips has produced consistently sharp apexes free of shank irregularities, permitting reproducible placement within 25–50 nm. These advances in tip design and spatial control have underpinned more reliable four‐point measurements and enhanced the study of surface conductivities at the nanoscale.

Multi-Probe Scanning Tunneling Microscopy Techniques publication trend

The graph below shows the total number of articles in multi-probe scanning tunneling microscopy techniques across all publications each year (not limited to Nature Index journals).

Technical terms

Scanning tunneling microscopy (STM): A technique that images and probes electronic states on a surface by measuring tunnelling current between a sharp metallic tip and the sample as a function of tip position.

Multiprobe STM: An extension of STM that employs two or more independently controlled tips to perform simultaneous or sequential measurements on the same sample.

Four‐point measurement: A configuration using at least four contacts to separate current injection from voltage sensing, minimising contact resistance errors in resistivity and conductivity studies.

Focused ion beam milling (FIB): A process that uses a beam of ions to sculpt or clean probe tips at the nanometre scale, improving tip sharpness and spacing precision.

References

1. Fabrication of on-chip probes for double-tip scanning tunneling microscopy. Microsystems & Nanoengineering (2020).
2. Two-probe STM experiments at the atomic level. Journal of Physics Condensed Matter (2017).
3. Consistent probe spacing in multi-probe STM experiments. AIP Advances (2020).