Effect of sweeping direction on the capacitance−voltage behavior of sputtered SiO₂/4H-SiC metal-oxide semiconductors after nitric oxide post-deposition annealing

The effect of sweeping direction on the capacitance–voltage (C–V) behavior of sputtered SiO₂/4H-silicon carbide (SiC) metal-oxide semiconductor capacitors was investigated. Nitric oxide post-deposition annealing was conducted for the sputtered SiO₂ on 4H-SiC. The sweeping direction of the measurement changed the C–V behavior and effective oxide charge density (Q _eff) because of trapped electrons at the accumulation and detrapped electrons at the depletion. The nitrogen atoms near interface between SiO₂ and 4H-SiC as a result of nitric oxide post-deposition annealing shifted the flat-band voltage in the negative direction. When the C–V was measured from depletion to accumulation, the absolute value of the Q _eff after 60 min long annealing, 3.465 × 10¹⁰ cm⁻² was less than that of the Q _eff after 30 min long annealing, −2.912 × 10¹¹ cm⁻². The mechanisms of the nitric oxide post-deposition annealing on sputtered SiO₂ on 4H-SiC are film densification and nitrogen passivation of the defects. (paper)