Observation of Kink effect in Carbon-doped GaN-on-Si HEMTs for Power Applications

For the first time, kink effect is observed in output characteristics of carbon-doped GaN-on-Si HEMT with gate length of 2.5$\mu \mathbf{m}$. This kink arises from the hot electron-assisted de-trapping mechanism and is affected by substrate bias. Experiments suggest that a negative potential is induced in the C-doped GaN buffer due to charge trapping, leading to increased probability of hot electron-assisted de-trapping due to the peak electric field in the channel. The effect of temperature on the kink reveals a non-monotonic behavior for both$\mathbf{V}_{DS,kink}$and kink amplitude.