Nano-scale materials characterization for quantum computing devices

Worldwide researchers embark in the endeavor to realize quantum computing hardware, and many challenges remain yet to be solved. Clearly, interdisciplinary efforts are needed to further advance the field, where one should not only rely on computer science, information science, and quantum physics but equally on materials science and experts in materials characterization [1]. The latter is crucial to establish an understanding and control of the (local) structure – function relationship in these systems. In practice, the functionality and performance (e.g. coherence time) heavily depend on the local, nanometre scale surface and interface properties such as stoichiometry, interface sharpness, oxides, impurities, etc. [1]. Here, atom probe tomography (APT), which enables 3-dimensional elemental mapping of materials with sub-nanometre spatial resolution [2], has been recently shown to provide valuable insights in these materials [3]. However, using APT to study semiconducting/superconducting qubits remains cumbersome and unreliable, mainly due to the immaturity of the APT technique itself and the intrinsic challenges when studying buried interfaces at nanometre length scales.

In this PhD project, you will develop routes for an accurate 3D compositional analysis of buried interfaces by APT, with focus on quantum computing applications. To achieve this, it will be crucial to gain fundamental insights in the underlying physical principles in APT. You will investigate various experimental and instrumental factors, establish means to translate them into (measurable) physical quantities and study their effect on the measured stoichiometry, spatial resolution, etc. Inevitably, this will require a deeper understanding of existing and, if needed, the development of new data processing schemes. Ultimately, the reliable APT results will be fed back to the materials scientists and process engineers at imec/KU Leuven to correlate them with functional properties and to optimize materials processing and device performance.   

To achieve this ambitious goal, you can rely on a broad set of material systems ranging from simple test materials up to complex devices. An excessive, state-of-the-art instrumentation park and access to data analysis and simulation/physical modelling software will give you sufficient support to solve this challenge. This PhD project is embedded in our APT research program. The outcome of your study will expand the application range of APT and will eventually serve the quantum computing research program at imec and KU Leuven.

[1] de Leon et al., Science 372, 253 (2021)

[2] B. Gault, Nature Reviews Methods Primers volume 1, 51 (2021)

[3] B. P. Wuetz, APS March 2021