Electrical performance of Sm₂O₃/ZrO₂ gate stacks on 4H-SiC via various O₂/N₂O gas concentrations

The bilayer thin film consists of sputtered Zr and Sm on 4H-SiC substrate electrical and structural characterization was evaluated. The sputtered bilayer underwent dry thermal oxidation by varying gas concentration ratio of O₂ and N₂O. The monoclinic phase of Sm₂O₃ and ZrO₂ in amorphous state was detected in XRD analysis. The revelation of amorphous bilayers revealed thickness in range of 7.95 to 8.42 nm via high-resolution transmission electron microscope (HRTEM) analysis. The band alignment modification exposed conduction band offsets (CBO) in the range of 2.24 to 2.59 eV. As the incorporation of N₂O affected the electrical properties where the 50% O₂: 50% N₂O has been revealed the highest electrical breakdown field, EBD of 9.8 MV/cm at a leakage current Jg of 10^–6 A/cm. At this concentration ratio, it also has the highest capacitance of 3.42 µF/cm² with a dielectric constant, k value of ~ 28.79. The Fowler–Nordheim (FN) tunneling conduction mechanism dominates in this work exposed barrier height, ΦB at 0.92 eV. The combination of Sm₂O₃ and ZrO₂ in a bilayer gate stack shows promising features that suitable as a high-k gate dielectrics to be used in MOS-based technologies.