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 (Qeff) 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 Qeff after 60 min long annealing, 3.465 × 1010 cm−2 was less than that of the Qeff 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.