Excess carrier mapping technique — A new parameter extraction method for 4H-SiC ambipolar power devices

This paper proposes for the first time a novel characterization technique that can directly profile the spatial excess carrier in the voltage supporting drift region of a power device based on inductive switching waveforms. The theory this method is based on is to translate the dv/dt during inductive switching to the local excess carrier (from V(t)-t to 6p(x)-x). The information of the extracted profile can be used to obtain (i) ambipolar lifetime and (ii) Stored excess charge at given current in the device and (iii) estimate the carrier density near the side where majority carrier is injected. This model is used to extract carrier distribution of a high voltage SiC IGBT and GTO but the model can also be applied to other bipolar devices such as Si IGBT.