High κ dielectric single-crystal monoclinic Gd2O3 on GaN with excellent thermal, structural, and electrical properties

MBE-grown single-crystal Gd 2 O 3 epitaxially on GaN has exhibited excellent thermal stability, withstanding rapid thermal annealing (RTA) at 1100 °C. The high-K dielectric Gd 2 O 3 thin film 10 nm thick has a monoclinic phase with a high degree of crystallinity, characterized by X-ray diffraction using synchrotron radiation. The orientation relationship is (402) Gd2O3 ∥(0001) GaN and Gd2O3 ∥(2110> GaN . Interface between Gd 2 O 3 and GaN remains atomically sharp after the RTA, as demonstrated using X-ray reflectivity and high-resolution transmission electron microscopy. Gd 2 O 3 /GaN metal-oxide-semiconductor capacitors show well-behaved capacitance-voltage characteristics with small dispersion and hysterisis, a high dielectric constant of ∼17, and a low electrical leakage current density of 4.6 × 10 -9 A/cm 2 at 1 MV/cm.