Pulsed-IV and drain current transient study of AlGaN/GaN HEMTs

Abstract

A study of pulsed-IV and drain current transients for unpassivated and SiN passivated AlGaN/GaN high electron mobility transistors (HEMTs) have been carried out in this report to observe the impact of traps in these devices. Pulsed-IV (PIV) characteristics for gate turn-on and gate turn-off to semi-on state for different pulsewidths (PW) reveal the effect of passivation. The unpassivated HEMT shows degraded characteristics suffering from significant current collapse due to surface states in the gate-drain access regions. Both devices observe kink in the drain current with passivated HEMT exhibiting kink for $\text{PW}\ > \ 30\ \ \mu s$. Drain current transient study from emission characteristics reveal traps with activation energies from 0.43-0.68 eV in the devices. The trapping phenomenon in unpassivated HEMT is governed by surface traps through virtual gate formation. The passivated HEMT checks the surface trapping but is vulnerable due to energetically deep bulk traps.