Impact of oxidation conditions in SiO2 atomic layer deposition on interface state densities at β -Ga2O3 (001) MOS interfaces with 600 °C post-deposition annealing

We investigated the impact of SiO2 film deposition conditions in either thermal or plasma-enhanced atomic layer depositions (ALDs) on the interface characteristics of β-Ga2O3 metal–oxide–semiconductor (MOS) capacitors, especially focusing on oxidation reaction conditions in ALD. The formation of the interface with an interface state density as low as ∼1011 eV−1 cm−2 at 0.2 eV below the conduction band edge and a low near-interface oxide trap density was achieved by tuning the O3-dose in thermal-ALD, with a post-deposition-annealing temperature limited to a relatively low temperature of 600 °C to avoid the thermally induced damages on Ga2O3. The fixed charge density at the SiO2/β-Ga2O3 interface was also minimized by thermal-ALD with the sufficient dose of O3. These results demonstrate the significant role of the control of SiO2 deposition conditions to achieve high-quality SiO2/β-Ga2O3 MOS interfaces with low-thermal-budget processes.