Epitaxial growth of lanthanide oxides La2O3 and Sc2O3 on GaN.

Deposition of lanthanide oxides on GaN is investigated as a means to produce stable dielectric with good interface quality. Epitaxial growth of cubic <111>-oriented Sc₂O₃ is observed on GaN [0001] with a lattice mismatch of 7.2%, whereas La₂O₃ growth, with a lattice mismatch of ∼21%, results in a mixed phase epitaxial film comprised of the bixbyite and hexagonal allotropes. Substantial roughening accompanies this mixed phase film. By inserting a thin Sc₂O₃ interfacial layer between La₂O₃ and GaN and a Sc₂O₃ capping layer, the crystal quality of the predominantly La₂O₃ layer is improved and the stack is stabilized against hydroxide formation under ambient conditions. [ABSTRACT FROM AUTHOR]