Hexagonal GdScO₃: An epitaxial high-κ dielectric for GaN

GdScO₃ was deposited by pulsed laser deposition on two different templates suitable for III-N growth: metalorganic vapour phase epitaxial GaN (0 0 0 1) on sapphire and molecular beam epitaxial Y₂O₃ on Si (1 1 1). The structure and crystallinity of the layers were determined as well as the band gap and permittivity of the material. It was found that GdScO₃ grows epitaxially and crystallizes hexagonally in contrast to the usually found orthorhombic or amorphous phases. A band gap and permittivity κ of 5.2 eV and 24 were found, respectively, making GdScO₃ a promising epitaxial gate dielectric for III-N transistor applications.