Speaker
Description
In this talk, based on recently published work [1], we introduce a novel scanning tunneling microscopy (STM) method called inverted-mode STM (IM-STM), an approach that offers a fundamentally new way to do STM and enables atomically precise fabrication via mechanosynthesis. Performing reproducible manipulation of covalently bonded atoms requires control over the atomic configuration of both sample and probe – a longstanding challenge in STM. By replacing the traditionally sharp STM tip with an annealable Si probe and using tailored organic molecules deposited on a Si(100) surface as mini-tips to image this probe apex, IM-STM effectively solves this problem and provides the necessary control of both sides of the tunnel junction.
These molecules are designed to react with the probe apex; the two sides of the tunnel junction can act as chemical reagents, which can be positioned with sub-angstrom precision. This allows the Si probe apex to be utilized as a "build site": an atomically-flat, crystalline mesa where abstraction or donation of atoms from or to the probe is possible, via interactions with the surface-bound molecules. The geometry of the probe apex further enables multiple molecules to sequentially interact with the same build site. We demonstrate this by using a novel alkynyl-terminated molecule to reproducibly abstract hydrogen atoms from an H-passivated Si(100) probe apex. This approach is expected to extend to other elements and moieties, opening a new avenue for scalable atomically precise fabrication with mechanosynthesis.
[1] E. Barrera et al., “Inverted-mode scanning tunneling microscopy for atomically precise fabrication,” arXiv:2512.24431 [cond-mat.mes-hall] (2025), https://doi.org/10.48550/arxiv.2512.24431 (submitted for peer review).
| Keyword-1 | Scanning tunneling microscopy |
|---|---|
| Keyword-2 | Atomically precise fabrication |
| Keyword-3 | mechanosynthesis |