The LEEM laboratory at Cardiff University:

Cardiff University hosts a unique Low Energy Electron Microscope (LEEM). This is the only instrument in the world able to image epitaxial dynamics in real-time during Molecular Beam Epitaxy under high As flux. It is a powerful research tool that provides unique insights into III-As compound semiconductor manufacturing.

Cardiff’s LEEM laboratory is devoted to the development of this experimental technique. The group has recently developed new imaging techniques enabling monitoring of the full phase diagram of a material and integrated state-of-the-art molecular beam epitaxy (MBE) capabilities within the microscope.

Our research:

Our projects aim to facilitate the integration of new compound semiconductor materials and new nanostructures to develop new technologies (e.g. photonics, spintronics). The group is developing a new methodologies that will enable to study key problems of epitaxial growth in a more efficient and direct way. The group benefits from the proximity of the Compound Semiconductor Cluster in South Wales, which provides a route to offer our observations to industrial partners (e.g., IQE). Our long-term goal is to become a reference world-wide to facilitate integration of materials, allowing them to fabricate more efficient sensors and communication devices enabling faster internet, safer cars, remote healthcare, etc.

It is said a picture is worth a thousand words. Low Energy Electron Microscopy produces tens of thousands of images in videos of growth dynamics. In order to process these vast amounts of information we are developing Artificial Intelligence (AI) techniques, in particular unsupervised learning and reinforcement learning, that enable us to increase our understanding of the possibilities of our research instrument, increase our ability to observe and interpret new phenomena. Finally, we expect our results to apply to any experimental technique where changes in small features can have significant physical meaning e.g., paving the way to real-time assistive technologies for experimental researchers using real space or reciprocal space imaging techniques.

LEEM measurement of a atomically flat trail created by a Ga droplet on GaAs (001) under As flux. The Ga droplet can be seen at the top of the trail. The different colours indicate different surface phases (yellow – c(8×2); red – 6×6; green – 3×1; blue – 2×4)