Our research vision is to explore the structure-electronic structure relationship in inorganic solids and how this manifests in their overall physico-chemical characteristics to integrate them into opto-electronic devices. We are an interdisciplinary team of experimentalists with key expertise in thin film synthesis, surface and interface chemistry, and X-ray photoelectron spectroscopy. Current research topics within the group include the following.

Materials and interfaces in power electronics

We work on both established and new generations of wide band gap materials for power electronics, including e.g., SiC and Ga₂O₃. Beyond investigating bulk properties of different crystal polymorphs and thin film orientations, we are particularly interested in the study of interfaces in power electronics using X-ray spectroscopy.

Sol-gel methods for thin films

We focus on developing sol-gel deposition methods for thin films of transparent conducting oxides (TCOs), a class of materials widely applied in device and display applications, including photovoltaics and LEDs. We develop and optimise deposition methods for high-quality, doped ultra-thin films of post-transition metal oxides. This is important to enable applications of new TCOs in devices as well as to enable the use of advanced characterisation techniques, where the ability to create high-quality, highly ordered samples is of great advantage.

We are particularly interested in the relationship between morphology, crystal structure, and electronic structure of these films to develop a complete understanding of the materials’ characteristics and, ultimately, their device behaviour.

Hard X-ray Photoelectron Spectroscopy (HAXPES)

HAXPES is one of the most powerful techniques to study the local chemical states and electronic structure of extended materials and heterostructures, e.g., those central to electronic devices. The high X-ray energies used enable larger depth information, making it possible to study buried layers and interfaces. We work on both the development and application of the technique across a broad spectrum of materials. We collaborate closely with beamline I09 at Diamond Light Source in trialling new measurement strategies and developing new in-situ and in-operando approaches to apply HAXPES to the often complex structures found in devices. We have also worked closely with Scienta Omicron, developing their laboratory-based HAXPES system.

Inorganic materials for biosensors

This strand of work started through a Newton Fund project, which aimed to develop a new Point of Care platform for glucose sensing based on oxide nanostructures rather than enzymes. Following this, we are continuing to work to further develop existing synthesis routes for oxide nanostructures and improve our understanding of how synthesis choices influence the materials’ physico-chemical properties and, ultimately, their sensing performance. A wide range of syntheses has been proposed in the literature, but we greatly lack an understanding of how synthesis parameters influence the morphology and surface chemistry of the resulting nanostructures.

X-ray radiation damage

As we are heavy users of X-ray-based techniques, including spectroscopy and diffraction, the question of how X-rays interact with matter is of great importance to us. Whilst X-ray radiation damage is well understood in biological systems, hardly anything is known about this effect in small molecular crystals and inorganic materials. We are part of a group of collaborators stretching from laboratory to synchrotron techniques, X-ray diffraction to X-ray spectroscopy, and experiment to theory, which is trying to establish a fundamental understanding of how the reaction of matter under X-ray radiation can be understood and what we can learn about the material itself.

Fundamental understanding of X-ray photoelectron spectra

Photoelectron spectra, including core, semi-core, and valence spectra, contain a wealth of information that even after 60+ years of the technique being used we are only starting to exploit. We use systematic spectroscopy experiment to explore spectral features with the goal to selectively enhance or discriminate certain features to obtain a detailed understand of their origin. This work necessitates the close collaboration with theory colleagues, which is essential for the understanding of complex spectral features. Part of this work is within the framework of the BETTERXPS Marie Skłodowska-Curie Actions Staff Exchange programm and the UK High-End Computing Consortium for X-ray Spectroscopy (HPC-CONEXS).

The bigger picture

In 2023, we worked with the Salters’ Institute to create a series of four videos for their Chemistry Club, an innovative online learning platform for 11-14-year-olds. The topics include semiconductors, display screens, computers, and power electronics and highlight some areas in which the group works. The videos are based on interviews with Aysha, Curran, and Anna and also feature video content of Prajna and Yujiang. You can also see some of the labs and offices we work in at UCL.

Links to the individual videos: