Structural and electrical characteristics of atomic layer deposited high κ HfO₂ on GaN

High κ Hf O2 was deposited on n -type GaN (0001) using atomic layer deposition with Hf (NC H3 C2 H5) 4 and H2 O as the precursors. Excellent electrical properties of TiNHf O2 GaN metal-oxide-semiconductor diode with the oxide thickness of 8.8 nm were obtained, in terms of low electrical leakage current density (∼ 10-6 A cm2 at VFB +1 V), well behaved capacitance-voltage (C-V) curves having a low interfacial density of states of 2× 1011 cm-2 eV-1 at the midgap, and a high dielectric constant of 16.5. C-V curves with clear accumulation and depletion behaviors were shown, along with negligible frequency dispersion and hysteresis with sweeping biasing voltages. The structural properties studied by high-resolution transmission electron microscopy and x-ray reflectivity show an atomically smooth oxide/GaN interface, with an interfacial layer of GaON ∼1.8 nm thick, as probed using x-ray photoelectron spectroscopy.