Atomic-scale devices made from individual dopant atoms in silicon offer a wealth of
opportunities to study new physical phenomena and to create novel technologies. For
example, the valence electron spin of a single dopant, or its nuclear spin, can be
exploited to form a qubit, the basic functional unit of a quantum computer.
Alternatively, artificial lattices of individual dopant atoms can provide the basis for
analogue quantum simulators. The deterministic placement of single dopant atoms in
silicon at nearly exact lattice sites is possible using the technique of scanning
tunnelling microscopy hydrogen resist lithography. However, until recently there have
been limits to the single-atom fabrication yield, a severe hinderance to device scaling. I
will explain how we have overcome these limits, and show that using arsenic-in-silicon
it is possible to achieve a single-atom yield approaching 100%, providing a fabrication
pathway to the scaling of single-atom devices [1,2]. Additionally, I will describe our
device fabrication effort and show preliminary electrical measurements from arsenic-
in-silicon devices made using hydrogen resist lithography. Finally, I will briefly show
how extreme ultraviolet (EUV) lithography can be used to selectively remove the
hydrogen resist, offering a route to fabricating interconnects for atomic-scale devices,
across an entire wafer [3].

References
[1] T.J.Z. Stock, et al., Advanced Materials 36, 2312282 (2024).
[2] T.J.Z. Stock, et al., ACS Nano 14, 3316 (2020).
[3] P.C. Constantinou, et al., Nature Communications 15, 694 (2024).