Identification of the donor in ZnO as a Sn-Li complex with large hyperfine interaction
Phys. Rev. B 114, 225417 – Published 23 October, 2026
DOI: https://doi.org/10.1103/bmh2-l3cy
Abstract
Donor impurities in wide direct band gap semiconductors provide a promising platform for spin-photon quantum technologies by combining a donor spin qubit with optically addressable transitions. In ZnO, the shallow donor with the largest reported binding energy has long been associated with the bound exciton line, but its microscopic origin has remained unresolved. Here we demonstrate the controlled formation and identification of this donor as a Sn-Li complex through a combination of ion implantation, annealing, optical spectroscopy, and first-principles calculations. Resonant two-laser coherent population trapping measurements reveal an electron– hyperfine interaction of , establishing a coupled electron-spin-1/2, nuclear-spin-1/2 system with one of the largest hyperfine couplings reported for shallow donors in semiconductors. Density functional theory calculations show that a nearest-neighbor complex has favorable formation energetics, donor character with the electron localized on Sn, and an extrapolated hyperfine interaction consistent with experiment. The large donor binding energy and excited-state structure indicate enhanced thermal robustness of the optical transition relative to conventional group-III donors, while the strong hyperfine interaction enables fast electron-nuclear spin control and prospects for direct nuclear-spin-photon interfaces. We further observe efficient optically induced nuclear spin polarization, highlighting a path toward nuclear spin initialization. More broadly, our results reveal how a donor-acceptor complex can access previously unexplored regimes of shallow donor physics, extending the design space of donor quantum defects beyond isolated substitutional dopants.
