Researchers develop a technique to detect defects at the atomic level in ultra-thin materials, a key advance for the semiconductor chip industry

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The Madrid Institute of Materials Science (ICMM-CSIC), an entity dependent on the Spanish National Research Council, together with the Autonomous University of Madrid, leads a work that has managed to demonstrate the effectiveness of a new technique for detecting defects in ultra-thin materials, just a few atoms thick.

The work, just published in the journal Nature Communications, responds to a pressing demand from the superconductor and electronic chip industry: as electronic devices become smaller and smaller, tiny defects in the materials that compose them can become critical and cause device failures, so being able to detect them is crucial.

To achieve this, this team has used lateral force microscopy (LFM), a technique that drags an ultra-fine tip, just a few atoms thick, over the material. With this, they have been able to record the friction force between two layers and, more importantly, to detect subsurface defects, those hidden under the top layer and the most difficult to locate.

"It was taken for granted that friction only notices the outermost layer of a material, but we have shown that it also carries information about what is underneath, and that it can be read with a simple instrument," states Guilherme Vilhena, CSIC researcher at the Madrid Institute of Materials Science and one of the study leaders.

Cristina Gómez-Navarro, researcher at the Autonomous University of Madrid and also a main author of the work, explains that each defect in the material "leaves a characteristic fingerprint." Thus, "a vacancy on the surface produces a signal of drop and rise, while a buried vacancy generates only an exit barrier, without the entry drop." It is this difference that reveals not only where the defect is, but also at what depth.

In this way, combining experiments with computational simulations, this research team has also demonstrated that the mechanism is geometric: "This implies that the technique should work equally for any two-dimensional material," adds UAM researcher Aitor Zambudio, also a member of the team.

"What is most surprising is that such a simple technique reaches the sensitivity necessary to 'see' a missing atom below the surface and, furthermore, to distinguish at what depth it is," points out Óscar Javier Gutiérrez, also a researcher at ICMM-CSIC and first author of the work.

A key work for the chip industry

The researchers argue that this work not only represents a milestone in the field of scanning probe microscopy, pushing the technique to its limit, but also opens a path of great impact for the semiconductor chip industry and the quality control of future devices.

The work is the result of the collaboration between the group of Guilherme Vilhena at ICMM-CSIC and the group of Cristina Gómez-Navarro at UAM, within the framework of the UAM+CSIC International Excellence Campus, with the participation of the University of Murcia and the Jagiellonian University of Krakow (Poland).

Referencia:

Oscar Gutiérrez-Varela, Aitor Zambudio, Pablo Ares, Julio Gómez-Herrero, Enrico Gnecco, Jaime Colchero, J. G. Vilhena*, and Cristina Gómez-Navarro. Unveiling Surface and Subsurface Atomic Vacancies in MoS2 with Lateral Force Microscopy. Nature Communications. DOI:  10.1038/s41467-026-75151-0