Investigation of Performance Degradation in Power MOSFET under OFF-State Avalanche Breakdown Test

Avalanche ruggedness is an essential feature to assure robust power converter operations. In this paper, the performance degradation of the power MOSFET under the OFF-state avalanche test is investigated in detail. For this purpose, a high resolution and cost-effective nano-second Current Pulse Generator (CPG) is designed for device avalanche capability test. Using high resolution PWM function of a digital signal processor (DSP), a high resolution current pulse can be generated in the order of 100 picoseconds. Using the same setup, the magnitude and duration of the current pulse width can be adjusted precisely. From the experimental results, a significant drop in the threshold voltage is observed after these tests, which leads to a noticeable shift of transfer and output characteristics. In addition, a large increase in drain leakage current and a gradual increase in on-state resistance were observed over the aging cycles. The electrical parameter shifts indicate a possible gate degradation after the device aging.