Dresden 2026 – scientific programme

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O: Fachverband Oberflächenphysik

O 56: Scanning probe techniques: Method development II

O 56.5: Talk

Wednesday, March 11, 2026, 11:30–11:45, HSZ/0401

Towards Atomically Precise Fabrication through STM with Flat, Crystalline Probes — •Marc Savoie, Eduardo Barrera Ramirez, Bheeshmon Thanabalasingam, and Marco Taucer — CBN Nanotechnologies Inc, Ottawa, Canada

Scanning Tunneling Microscopy (STM) enables the fabrication of atomically precise structures. Traditionally, STM probes manipulate atoms on the sample surface, but this presents challenges for fabricating covalently bonded structures. The high strength of covalent bonds means that detailed knowledge and control over both the probe and sample sides of the tunneling junction is required to form the desired bond and avoid unwanted changes. We introduce inverted-mode STM, an approach that reverses the roles of probe and sample to enable mechanically controlled chemical reactions for atomically precise fabrication. We have developed flat, crystalline Si(100) STM probes that act as the substrate for atomic manipulations. The flat probe is imaged by tailored, 3D molecules deposited on a surface. By determining the orientation of the molecule, the challenge of knowing the atomic configuration on both sides of the junction is effectively resolved. Treating the two sides of the tunnel junction as reagents whose relative positions can be controlled with sub-angstrom precision, we show that hydrogen atoms can be reproducibly abstracted from a locally flat, crystalline region of the probe apex at zero volts using a novel molecule terminated in an alkynyl radical. Multiple surface-bound reagents can sequentially address the same build site on a probe apex. The approach is expected to apply to abstraction and donation of other elements and moieties.

Keywords: Scanning tunneling microscopy; semiconductor nanofabrication; hydrogen abstraction; mechanosynthesis; atomically-precise fabrication