Experimental/numerical investigation on current collapse in AlGaN/GaN HEMT's

Rf current collapse is investigated in AlGaN/GaN HEMT's by means of pulsed, transient, and small-signal measurements. Numerical device simulations are presented, showing that the concomitant presence, at the ungated device surface, of polarization-induced charges and hole traps can explain, without invoking any other hypothesis, all dispersion effects observed experimentally.