International Exchange Award: Exploring s-SNOM capabilities for probing ion implantation profiles

Dr Xinyun Liu visiting Prof Rainer Hillenbrand's lab in CIC nanoGUNE. The unique narrowband THz-SNOM as shown in the photo allows us to study the carriers introduced by ion implantation.

Xinyun Liu, a Postdoctoral Research Associate in the Boland group at the University of Manchester was awarded an M4QN international exchange award to visit Prof. Rainer Hillenbrand at the nanoscience research centre CIC nanoGUNE in San Sebastian. The visit took place from 21-29 March 2026.

Exploring s-SNOM capabilities for probing ion implantation profiles

As a world-leading research group in scattering-type scanning near-field optical microscopy (s-SNOM), Professor Rainer Hillenbrand’s group at CIC nanoGUNE has been at the forefront of instrumental and methodological developments in this field. During this visit, several ion-implanted samples were measured using state-of-the-art s-SNOM systems. These measurements enabled detailed investigation of ion implantation profiles in both in-plane and out-of-plane directions. The study demonstrates the potential of s-SNOM as a powerful tool for nanoscale characterisation of implanted regions, offering high spatial resolution and sensitivity to local optical and electronic properties.

Benefits to the UK materials and quantum community

Ion implantation is a key technique for fabricating nanostructures in quantum devices, such as qubits and single-photon emitters. Accurate characterisation of ion-implanted regions is therefore essential for optimising implantation parameters and improving device performance.

Conventional characterisation methods, such as secondary ion mass spectrometry (SIMS), transmission electron microscopy (TEM) and Raman spectroscopy, often face trade-offs between spatial resolution, sample preparation complexity, and non-destructive measurement. In this study, by carefully selecting ion species and host substrates, s-SNOM enables probing of implantation profiles via phonon-assisted and carrier-assisted contrasts. The complementary s-SNOM capabilities of the Boland group at the University of Manchester and Professor Hillenbrand’s group at CIC nanoGUNE allow for comprehensive characterisation of ion-implanted regions. This approach provides an alternative method with high surface sensitivity (<100 nm), minimal sample damage and simplified preparation requirements.

Importantly, the results from s-SNOM characterisation can be directly fed back into the ion implantation process, facilitating optimisation of ion beam alignment and processing parameters. This aligns strongly with the aims of M4QN by advancing nanoscale characterisation techniques for quantum materials and devices.

Visit Outcomes

A strong collaborative link has been established between the Boland group (University of Manchester) and the Hillenbrand group (CIC nanoGUNE), creating a foundation for future joint research activities leveraging complementary s-SNOM capabilities.
Significant knowledge exchange took place, including experimental optimisation strategies, data processing techniques, and interpretation of results. Xinyun gained hands-on expertise in s-SNOM system alignment, which is critical for establishing stable and reproducible measurements at the University of Manchester.
Technical data was successfully collected for three sets of ion-implanted samples. Clear contrast between implanted regions and host substrates was observed in all cases, demonstrating the effectiveness of the technique. These results are expected to lead to two or three high-quality publications.