Studies of Bias Temperature Instabilities in 4H-SiC DMOSFETs

Bias Temperature Instability (BTI) measurements were performed on SiC n-channel DMOSFETs. The effects of the BTI stress on the electrical characteristics of the device were studied using slow and fast measurements. The slow Measurements show that the change in threshold voltage (Vth) can be attributed to charge carrier trapping/de-trapping at border traps, while interface trapped charge density is found to be unaffected. The fast measurements, however, shows significant Vth recovery taking place in-situ during measurement. Moreover, Vth shift is observed to decrease with increasing temperature for the same stress level suggesting that Vth recovery is temperature activated.