Polarization-Charge Inversion at Al2O3/GaN Interfaces through Post-Deposition Annealing

Abstract

The effects of post-deposition annealing (PDA) on the formation of polarization-charge inversion at ultrathin Al2O3/Ga-polar GaN interfaces are assessed by the analysis of energy band bending and measurement of electrical conduction. The PDA-induced positive interface charges form downward energy band bending at the Al2O3/GaN interfaces with polarization-charge inversion, which is analyzed using X-ray photoelectron spectroscopy. Net charge and interface charge densities at the Al2O3/GaN interfaces are estimated after PDA at 500 °C, 700 °C, and 900 °C. The PDA temperatures affect the formation of charge densities. That is, the charge density increases up to 700 °C and then decreases at 900 °C. Electrical characteristics of GaN Schottky diodes with ultrathin Al2O3 layers exhibit the passivation ability of the Al2O3 surface layer and the effects of polarization-charge inversion through PDA. This result can be applied to improvement in GaN-based electronic devices where surface states and process temperature work important role in device performance.

Applications of Thin Films in Microelectronics

“…Additionally, Al 2 O 3 /GaN interfaces were assessed for power switching components with a high breakdown field, direct wide bandgap, radiation hardness, high electron mobility, and high saturation velocity [14]. In this research, the authors showed that the electrical conduction in GaN Schottky diodes improved with the application of postdeposition annealing, mainly due to the formation of positive surface polarity at both gate and surface areas in addition to the passivation ability of Al 2 O 3 on the surface area.…”