Controlled Growth Temperatures of High Dielectric Constant Gallium Cerium Oxide Layer on 4H-Silicon Carbide Substrate

Abstract

The potential of using gallium cerium oxide (Ga_xCe_yO_z) as a passivation layer (PL) on 4H-silicon carbide (SiC) substrates were thoroughly assessed after annealing in nitrogen–oxygen–nitrogen (N₂–O₂–N₂) ambient at varying temperatures of 600, 700, 800, and 900°C. It was observed that nitrogen ions introduced during the annealing process were predominantly attached to oxygen vacancies (V_o) within the oxide layer at lower temperatures (600 and 700°C), whereas at elevated temperatures (800 and 900°C), there was a substantial increase in the migration of nitrogen ions toward the interface of Ga_xCe_yO_z/4H-SiC. Analysis employing X-ray photoelectron spectroscopy (XPS) corroborated the transformation of Ce³⁺ to Ce⁴⁺ at 900°C due to enhanced reoxidation. As a result, the passivation of V_o at 800 and 900°C led to a significantly higher dielectric constant, improved breakdown field, and favorable values for slow trap density (STD), interface trap density, interface state density, as well as effective oxide charge, highlighting the potential of Ga_xCe_yO_z PL on 4H-SiC for use in metal–oxide–semiconductor (MOS) applications.