Characteristics of Schottky contacts on n-type 4H–SiC using $IrO2$ and $RuO2$ Available to Purchase

Thermally stable Schottky contacts on n-type 4H–SiC with high Schottky barrier height were demonstrated by annealing the rare earth metal contacts (Ir and Ru) under $O2$ ambient. The formation of rare earth metal oxides $(IrO2$ and $RuO2)$ after $O2$ annealing led to the increase of Schottky barrier height (>1.9 eV) and a low reverse leakage current $(∼10−9 A/cm2).$ Synchrotron radiation photoemission spectroscopy showed that the work function of $IrO2$ is higher about 0.23 eV than that of Ir and the binding energies of Si $2p$ and C $1s$ shifted toward lower binding energies by 0.12 eV in both $O2$ and $N2$ annealed samples. The oxidation annealing caused predominant Si outdiffusion to the $IrO2$ $(RuO2),$ leaving Si vacancies behind, leading to the shift of surface Fermi level to the energy level of Si vacancy. Both the formation of oxide and the Fermi level movement played a role in forming the Schottky contact with high barrier height and excellent thermally stability.