MBE grown high κ dielectrics Ga2O3(Gd2O3) on GaN

High κ Ga2O3(Gd2O3) dielectric was deposited on n-type GaN (0 0 0 1) using molecular beam epitaxy (MBE). TiN/Ga2O3(Gd2O3)/GaN metal–oxide–semiconductor (MOS) diodes have exhibited a negligible frequency dispersion, low leakage currents (∼10−8 A/cm2), and a low interfacial density of states (Dit) of 1011 cm−2 eV−1 at the midgap. Well-behaved capacitance–voltage (CV) curves with accumulation and depletion behaviors were shown, with a dielectric constant of 14.7. Forming gas annealing at 600 °C has reduced the frequency dispersion in the CV curves. A sharp oxide/semiconductor interface was shown by high-resolution transmission electron microscopy (HR-TEM).