Speaker
Description
Here, we present an atomically precise fabrication (APF) approach based on bottom-up, building of covalently bonded structures on surfaces through the addition, abstraction, and manipulation of individual atoms or small few-atom moieties/functional groups. Our approach to mechanosynthetic APF is enabled by Inverted-Mode Scanning Tunneling Microscopy (IM-STM), a technique that uses tailored 3D molecules deposited on a sample to scan and react with a flat, crystalline silicon probe, enabling reagent transfer to the probe apex with sub-angstrom precision. This capability opens potential pathways for deterministic placement of qubit structures at specific atomic sites and orientations, as well as precise surface patterning or modification of materials.
We demonstrate the site- and orientation-specific formation of C2H on a Si(100) probe apex through IM-STM. The probe interacted with custom-synthesized 3D molecules (MAOGe-C2H) presenting an upright C2H moiety, or “feedstock”, which have relevance for quantum applications as the main constituent in T centres. By precisely moving the probe, the feedstock can be positioned at a specific silicon dimer on the probe, and a tailored X-Y-Z trajectory can be leveraged to transfer C2H in the desired configuration and orientation.
Through the choice of trajectory, C2H could be transferred to a single dimer or between two dimers, with success rates of 87 ± 4% and 72 ± 1%, respectively. Simulated STM images using Density Functional Theory showed strong agreement with experiments, providing high confidence in the proposed atomic configurations. Structures containing numerous C2H units were consistently fabricated, with controlled molecule orientation in each transfer.
Our ability to reproducibly control the position and orientation of individual molecules during transfer via mechanosynthesis represents a significant advance in APF. These results open new avenues for future development of complex, functionally relevant structures at the atomic scale and could also inform future efforts in qubit integration, T centre fabrication, and atomically precise surface engineering.
| Keyword-1 | Atomically precise fabrication |
|---|---|
| Keyword-2 | STM |
| Keyword-3 | Semiconductors |