Effect of Irradiation with 15-MeV Protons on Low Frequency Noise in Power SiC MOSFETs

Low frequency noise is studied in 4H-SiC power metal-oxide-semiconductor field-effect transistors (MOSFETs) irradiated with 15-MeV protons. Irradiation is carried out at room temperature in the frequency range from 1 Hz to 50 kHz upon irradiation with doses Φ of 1012 to 6 × 1013 cm–2. The frequency dependence of the spectral noise density SI follows the law SI ∝ 1/f with good accuracy. A correlation between the saturation current of the output characteristic Id(Vd) and the low-frequency noise level is traced. At doses in the range 1012 cm–2 ≤ Φ ≤ 6 × 1013 cm–2, the saturation current varies within about 20%, whereas the noise level changes by two orders of magnitude. The results of noise spectroscopy are used to estimate the trap density in the gate oxide, Ntv. In unirradiated structures, Ntv ≈ 5.4 × 1018 cm–3 eV–1. At Φ = 6 × 1013 cm–2, Ntv increases to ~7.2 × 1019 cm–3 eV–1.