The goal of this Presidential Young Investigator grant is to determine local electronic structure of defects in ceramics. The research uses scanning tunnelling microscopy with simultaneous photoexcitation to increase the free carrier concentration. Preliminary results have identified the potential to use this technique to identify structural and chemical defects in these wide band gap materials. The observed increase and distinct variation in the conductance is a detector of photoexcitation processes, allowing optical spectroscopy to be performed with the spatial resolution of scanning tunnelling microscopy. The research is being done on silicon carbide and zinc oxide. The effects of valence-to-conduction band excitation and defect-to- conduction band excitation are being isolated. Reflection, transmission electron microscopy and spectrophotometry are being used as collaborative techniques.
