Abstract
In this paper, the degradation behavior of the electrical characteristics was investigated, and trap analysis based on low-frequency noise (LFN) was carried out for the commercial 1.2-kV /30-A silicon carbide (SiC) power MOSFETs under repetitive short-circuit (SC) stress. The experiment results show that the on-state resistance ( ${R} _{\mathrm{ dson}}$ ) and threshold voltage ( ${V} _{\mathrm{ th}}$ ) increase significantly. Meanwhile, the drain-source current ( ${I} _{\mathrm{ ds}}$ ) decreases obviously with the increase of the SC cycles. Furthermore, the gate-source leakage current ( ${I} _{\mathrm{ gss}}$ ) of the SiC power MOSFETs increase greatly and the blocking characteristics deteriorated after 1000 SC cycles. The positive shift was observed on the gate-capacitance versus gate-voltage ( ${C} _{\mathrm{ g}}$ - ${V} _{\mathrm{ g}}$ ) curve, which shows that the damage region could be in channel along the SiC/SiO2 interface after repetitive SC stress. In order to obtain the trap information, trap characterization was performed by using LFN method, and the LFN results show that the trap density increases with the SC cycles. The physical mechanism could be attributed to electrically active traps generated at SiC/SiO2 interface and oxide layer due to the peak ionization rate, the perpendicular electrical field and high temperature during SC stress. The study may be useful to provide reference for converters design and fault protection of SiC power MOSFETs.
Highlights
Silicon carbide (SiC) material has been recognized as a prime option for increasing the power density, system switching frequency and system efficiency of power electronics due to its superior properties [1]–[3]
The repetitive SC stress leads to the degradation of the devices, such as the significantly increase of the Ron and Vth
The Igss increase greatly and blocking characteristics of the silicon carbide (SiC) power MOSFET were deteriorated after 1000 cycles of SC stress
Summary
Silicon carbide (SiC) material has been recognized as a prime option for increasing the power density, system switching frequency and system efficiency of power electronics due to its superior properties [1]–[3]. The degradation behavior of the electrical characteristics was investigated, and trap analysis based on LFN was carried out for the commercial 1.2-kV/30-A SiC power MOSFETs under repetitive SC stress. At the beginning of the gate pulse, Ids rise rapidly to a peak value of 294 A It keeps decreasing during the stress time due to the increase of junction temperature, and it is in agreement with previous result [24]. Under the conditions of Vgs = 20 V and Ids = 20 A, the typical Rdson value increase from 91.34 m to 113.55 m after 1000 SC cycles It indicates that the effect of SC stress on the device is notable, and the results are in agreement with previous results [8].
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