Eu2O3 hexagonal and monoclinic phase on GaN (0001) by MBE*

One major issue preventing large scale manufacturing of GaN-based MOS devices is the lack of a high quality, thermally and chemically stable gate dielectric. Many different insulators have been grown for that purpose on GaN (0001). Here we report on the epitaxial growth of the “high-pressure” hexagonal phase of Eu2O3 on C-plane GaN (0001) by molecular beam epitaxy. A structural phase transition from the hexagonal to the monoclinic phase was observed with increasing film thickness by ex-situ X-ray diffraction 2theta-theta scans and reciprocal space maps. A conduction band offset of 0.8 eV between GaN and Eu2O3 was measured by XPS making Eu2O3 feasible as a gate dielectric for a high electron mobility n-type channel GaN-based field effect transistor.