DC to RF drain current collapse in GaN-based High Electron Mobility Transistors (HEMTs) has been shown to strongly limit the output power density at microwave frequencies. The surface passivation can reduce these detrimental effects [1] but recently low current dispersion has been demonstrated even on unpassivated devices [2-3]. We report on unpassivated GaN/AlGaN/GaN HEMTs grown on SiC substrate both with intentionally undoped and doped carrier layer: extremely low drain current collapse in the order of few percent even for 50ns pulses was obtained by means of turn-on gate-lag measurements. The presence of relatively shallow electron traps within the GaN cap layer could explain the observed behaviour
Experimental and Simulated Gate Lag Transients in Unpassivated GaN/AlGaN/GaN HEMTs
PIEROBON, ROBERTO;RAMPAZZO, FABIANA;MENEGHESSO, GAUDENZIO;ZANONI, ENRICO;
2004
Abstract
DC to RF drain current collapse in GaN-based High Electron Mobility Transistors (HEMTs) has been shown to strongly limit the output power density at microwave frequencies. The surface passivation can reduce these detrimental effects [1] but recently low current dispersion has been demonstrated even on unpassivated devices [2-3]. We report on unpassivated GaN/AlGaN/GaN HEMTs grown on SiC substrate both with intentionally undoped and doped carrier layer: extremely low drain current collapse in the order of few percent even for 50ns pulses was obtained by means of turn-on gate-lag measurements. The presence of relatively shallow electron traps within the GaN cap layer could explain the observed behaviour
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