Characteristics of Al$_2$O$_3$ film by introducing additional oxygen and oxygen vacancy using Pt catalytic

Al$_2$O$_3$ is an attractive gate insulator for gallium nitride power device. It remains a big issue of mobility degradation because of oxygen vacancy (Vo) of Al$_2$O$_3$ film. Furthermore, little is known about influence of the Vo of Al$_2$O$_3$ on transistor property. In this paper, we study characteristics of Al$_2$O$_3$ insulator by introducing additional oxygen and Vo. We prepared p-Si(100)/SiO$_2$/Al$_2$O$_3$/Pt capacitors. These capacitors were annealed at 300 - 600 °C in N$_2$, O$_2$ and 3\% H$_2$ ambient to introduce additional oxygen and Vo into Al$_2$O$_3$ using Pt catalytic effect. The fixed charge density in Al$_2$O$_3$ film was negligible small from linear relationship between Vfb and Al$_2$O$_3$ thickness. The Vfb shift of capacitors which annealed at 300 - 600 °C in N$_2$ ambient exhibited about +0.6 V compared to the ideal Vfb. This is dominantly due to the dipole at Al$_2$O$_3$/SiO$_2$ interface. In contrast, the Vfb shift increased from +0.6 to +1.9 V with increasing the annealing temperature in O$_2$ ambient. The strength of the dipole increase because additional oxygen introduced by Pt catalytic effect piled up at Al$_2$O$_3$/SiO$_2$ interface. This suggests that the oxygen concentration at Al$_2$O$_3$/SiO$_2$ interface plays an important role of Vfb shift.