Characterization of a dielectric/GaN system using atom probe tomography

Characterization of Al₂O₃ gate dielectric on GaN using pulsed laser Atom Probe Tomography is reported. Atomic layer deposition was used to grow 5 nm of aluminum oxide on Ga-polar GaN. No oxidation of the surface of the semiconductor was observed and the interface was found to be non-abrupt. A significant amount of carbon impurities (10¹⁹/cm ³) were detected in the dielectric film that matches well with the estimated bulk trap density from C-V measurements. Our experiments suggest possible correlation between trap-related electrical hysteresis and the observed impurity concentration in these films.