III-Nitride Semiconductors

We are interested in the surface and interface properties of nitride semiconductors. GaN and related III-V nitrides (InN, AlN) are candidates for use in high-temperature microelectronic devices and used in blue wavelength light-emitting diodes and lasers. Despite success in the growth and application of these materials, the basic physics underlying the intentional doping of the films, the nature of defects, and the formation of metal overlayers remains to be determined. All of these problems are related directly to the detailed electronic structure of the nitrides, and yet this structure has not been extensively measured. The development of these nitrides as electronic materials requires that their defect and dopant electronic structure be fully understood. In collaboration with Prof. Ted Moustakas from the BU College of Engineering, we undertake a comprehensive determination of the detailed electronic structure of thin film refractory nitrides. Specifically, the electronic structure of defects and dopants in these nitrides is being studied, as well as the electronic structure of the interface between the films and their substrates, and between the films and metal overlayers. Furthermore, the chemical reactivity of the films (in particular, when defective or doped) is being investigated in order to understand the nature of adhesion of these nitrides to both substrates and overlayers, and to understand the chemical stability of the films at elevated temperatures or in model corrosive environments.