Characterization of trapping and thermal dispersion in GaN HEMTs

Dispersion in a GaN HEMT, including gate and drain lag, is related to a new trapping model based on SRH theory. Measurements and SPICE simulation are used to verify the capability of this model to explain the bias-and terminal-potential dependency of the turn-on transients and their time constants. The models of both drain current and trapping need to consider temperature and power dissipation versus time. The interaction between two different trap mechanisms and two different self-heating processes is shown to adequately explain the different characteristics of the turn-on transient of the transistor under test.