Experimental and numerical investigation of Poole-Frenkel effect on dynamic RON transients in C-doped p-GaN HEMTs

In this paper, we investigate the influence of Poole-Frenkel Effect (PFE) on the dynamic RON transients in C-doped p-GaN HEMTs. To this aim, we perform a characterization of the dynamic RON transients acquired during OFF-state stress (i.e., VGS,STR = 0 V < VT, VDS,STR = 25–125 V) and we interpret the results with the aid of numerical simulations. We find that dynamic RON transients at room temperature accelerate with VDS,STR1/2, which is signature of PFE, as further confirmed by the simultaneous decrease of the activation energy (EA) extracted from the Arrhenius plot of the dynamic RON transients at VDS,STR = 50 V and T = 30–110 °C. Results obtained by means of calibrated numerical simulations reproduce the exponential dependence of transients time constants (τ) on VDS,STR1/2 and consequent EA reduction only when including PFE enhancement of hole emission from dominant acceptor traps in the buffer related to C doping. This result is consistent with the model that considers hole emission from acceptor traps (rather than electron capture) as the mechanism underlying dynamic RON increase during OFF-state stress.