We investigated the effect of post-metallization forming gas annealing (FG-PMA) on SiO2/β-gallium oxide β-Ga2O3(001) MOS structures. We found that FG-PMA at a relatively low temperature (200–400 °C) efficiently reduced the interface and near-interface defects, resulting in improvements to device performance and reliability. By performing FG-PMA after post-deposition annealing in O2 and N2 atmospheres, the interface state density near the conduction band edge of Ga2O3 was reduced to as low as (4–7) × 1010 eV−1 cm−2. The significant improvement in electrical properties was attributed to the passivation of electrical defects by hydrogen atoms.
Maeda et al. (2025) studied this question.