Electric Field and Self-Heating Effects on the Emission Time of Iron Traps in GaN HEMTs

In this article, we separately investigate the role of electric field and device self-heating (SHE) in enhancing the charge emission process from Fe-related buffer traps (0.52 eV from E
_c
) in AlGaN/GaN high electron mobility transistors (HEMTs). The experimental analysis was performed by means of drain current transient (DCT) measurements for either: 1) different dissipated power ( P
_D,steady
) at constant drain-to-source bias ( V
_DS,steady
) or 2) constant P
_D,steady
at different V
_DS,steady
's. We found that: 1) an increase in P
_D,steady
yields an acceleration in the thermally activated emission process, consistently with the temperature rise induced by SHE and 2) on the other hand, the field-effect turned out to be negligible within the investigated voltage range, indicating the absence of the Poole-Frenkel effect (PFE). A qualitative analysis based on the electric field values obtained by numerical simulations is then presented to support the interpretation and conclusions.