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

Low frequency noise is studied in 4 H -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 10 12 to 6 × 10 13 cm –2 . The frequency dependence of the spectral noise density S I follows the law S I ∝ 1/ f with good accuracy. A correlation between the saturation current of the output characteristic I d ( V d ) and the low-frequency noise level is traced. At doses in the range 10 12 cm –2 ≤ Φ ≤ 6 × 10 13 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, N tv . In unirradiated structures, N tv ≈ 5 . 4 × 10 18 cm –3 eV –1 . At Φ = 6 × 10 13 cm –2 , N tv increases to ~7 . 2 × 10 19 cm –3 eV –1 .