Some Assembly Required: Building Materials from the Atom Up

Taleana Huff
Cross-appointed between Chemistry and Physics Dept. at Queen's

Abstract

“What would happen,” Feynman asked in 1959, “if we could arrange the atoms one-by-one the way we want them?” That is, what if instead of fabricating materials and devices from the top down, we could build them from the atom up, with all the precision and tunability over properties this control would confer? Atomically precise manufacturing (APM) aims to do just that: to control the composition, structure, and properties of materials with atomic-scale precision. Reaching this goal requires not only the ability to manipulate and characterize individual atoms and molecules, but also an understanding of how chemical bonds form, break, and reorganize at surfaces, as well as some pretty specialized tools.

I will begin by introducing our specialized atom-moving tools, Scanning Tunnelling Microscopy (STM) and Atomic Force Microscopy (AFM), and how they allow us to image, probe, and manipulate matter at the level of individual atoms. From there, I will survey the state of the art in atomically precise fabrication, highlighting some key challenges that remain: creating structures that survive elevated temperatures, expanding APM to technologically important but challenging covalent materials like semiconductors, building precisely in three dimensions, and paths for atom-scale fabrication to address human-scale needs. 

I will then discuss how my lab is tackling several of these challenges, beginning with N-heterocyclic carbenes (NHCs). NHCs are a versatile class of molecules that form strong bonds to metal surfaces while remaining capable of surface-wide self-assembly. Self-assembly (the molecules arranging themselves) offers a route to scaling atomically precise fabrication without the slow-down of requiring us to place every atom individually. By examining their adsorption, self-assembly, and interactions on different surfaces, we are exploring how molecular chemistry can be used to modify surfaces and direct materials growth, with implications for next-generation semiconductor manufacturing.

Finally, I will turn to the opposite problem: rather than creating uniform materials at scale, can we deliberately build useful imperfections? Atomic-scale defects such as nitrogen vacancy (NV) centres in diamond and T-centres in silicon possess electronic and spin properties useful for quantum sensing and computing. I will discuss our approaches toward atomically precise fabrication of spin-active defect centres using STM and AFM, including preliminary results using a new class of high-symmetry molecules called “tetragems” that host carbon-centred radicals. 

So, while some assembly is still required, Feynman’s 1959 question is becoming less hypothetical: we are learning to arrange atoms, one by one, the way we want them, building materials from the atom up.

Timbits, coffee, tea will be served in STI A before the colloquium.