Experimental and numerical investigation of Poole-Frenkel effect on dynamic R (ON) transients in C-doped p-GaN HEMTs

In this paper, we investigate the influence of Poole-Frenkel effect (PFE) on the dynamic R (ON) transients in C-doped p-GaN HEMTs. To this aim, we perform a characterization of the dynamic R (ON) transients acquired during OFF-state stress (i.e. V (GS,STR) = 0 V < V (T), V (DS,STR) = 25-125 V) and we interpret the results with the aid of numerical simulations. We find that dynamic R (ON) transients at room temperature accelerate with V (DS,STR) (1/2), which is signature of PFE, as further confirmed by the simultaneous decrease of the activation energy (E (A)) extracted from the Arrhenius plot of the dynamic R (ON) transients at V (DS,STR) = 50 V and T = 30 degrees C-110 degrees C. Results obtained by means of calibrated numerical simulations reproduce the exponential dependence of transients time constants (tau) on V (DS,STR) (1/2) and consequent E (A) reduction only when including the PFE-enhancement model of hole emission from dominant acceptor traps in the buffer related to C doping. This result is consistent with the 'hole-redistribution' model that considers hole emission from acceptor traps (rather than electron capture) as the mechanism underlying dynamic R (ON) increase during OFF-state stress.