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.