High- V TH E-Mode GaN HEMTs With Robust Gate-Bias-Dependent V TH Stability Enabled by Mg-Doped p-GaN Engineering

This is the authors' abstract. We don't add key points for this paper.

Highly stable threshold voltage(VTH)characteristics are an essential reliability requirement for p -GaN/AlGaN/GaN high-electron-mobility transistors (p-GaN HEMTs) to withstand various gate bias stresses for power applications. In this work, we demonstrate high-VTH(3.0 V) p-GaN HEMTs with robustVTHstability by p -GaN gate engineering via Mg doping and activation. TheVTHdegradation rates of the resulting device under both pulsed-I/Vand bias temperature instability (BTI) stress conditions are less than 10% at high temperatures up to 150°, which is much lower than that of conventional Schottky-type p -GaN HEMTs (20%–30%). Such notableVTHcharacteristics are due to the impact ionization (I.I.)-dependent hole compensation under certain gate stress, which effectively alleviates the electron trapping effect and reduces positiveVTHshift. The I.I. occurring in the fully depleted p -GaN layer has been confirmed by both positive temperature-dependent gate breakdown characteristics and numerical simulations. Furthermore, shallow- and deep-level hole traps are identified in the gate-stack of high-VTHdevices by performing the deep-level transient spectroscopy (DLTS) technique. Consequently, the trapping effect associated with hole traps may also alleviate the undesired electron-trapping-inducedVTHshift. These results provide a critical understanding of theVTHstability of the high-VTHp -GaN HEMTs (HVT-HEMTs) and important design guidance for commercial device development.