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 kappa of 5.2 eV and 24 were found, respectively, making GdScO3 a promising epitaxial gate dielectric for III-N transistor applications.