Tailoring oxide functionalities via defect engineering and surface functionalisation

Adopting oxide materials as basis for electronic devices is largely driven by the prospect of fully transparent electronics, which offer applications unattainable by conventional silicon technology, such as smart windows and transparent displays. The rich emergent properties in oxides resulted from the correlated interactions between electrons, spins, orbitals etc. also provide an exciting playground for us to explore novel functionalities and device concepts based on oxides. Using advanced synchrotron-based spectroscopies, we identify the critical roles played by defects (e.g. oxygen vacancies) in the microscopic origin of room-temperature ferromagnetism in diluted magnetic oxide systems. This understanding can enable us to develop oxide spintronics through defect engineering.

Surface functionalisation of oxides provides us with another route to tailor the oxide surface electronic properties. By terminating oxide surface with different functional groups we are able to tune the oxide surface energetics at molecular scale. We are particularly interested in the surface hydrogenation of TiO2, and are exploring the surface transfer doping of TiO2 to enable p-type surface conductivity on TiO2, which is difficult to be achieved via conventional doping approach.