CH029

Interest in the integration of wide bandgap oxides, such as the rocksalts MgO and CaO, lies in the possibility of optimizing High Electron Mobility Transistor (HEMT) structures, as well as the potential for combining the polar semiconductor GaN with ferroic materials, in which the interaction between GaN??s polar axis and the reorientable polarizations found in such materials as ferroelectrics can be leveraged. In either case, the epitaxial growth of rocksalt oxides on GaN is of interest, because of the need for passivation layers in the case of HEMT structures, and because of the need for tunneling barriers in the GaN/ferroelectric structures (due to the expected small band offsets between such materials). Here we report on spectroscopic studies of the MgO/GaN and CaO/GaN systems, focusing on growth mode determination, band alignment, and phase stability (particularly as it relates to water uptake under atmospheric exposure).