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

Abstract

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 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 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, N_tv. In unirradiated structures, N_tv ≈ 5.4 × 10¹⁸ cm^–3 eV^–1. At Φ = 6 × 10¹³ cm^–2, N_tv increases to ~7.2 × 10¹⁹ cm^–3 eV^–1.