Semiconducting p-GaN gate HEMT with avalanche-like non-destructive breakdown capability

Abstract

Non-destructive avalanche breakdown is crucial for enhancing the robustness of power devices against overvoltage stresses and surge energy, whereas state-of-the-art GaN HEMTs present no avalanche capability. In this work, we demonstrate a semiconducting p-GaN gate HEMT (SG-HEMT) that achieves avalanche-like non-destructive breakdown capability. A thin p-GaN layer covering the AlGaN layer serves as the intrinsic gate, with a control electrode formed outside the active region. This thin p-GaN layer (i.e., the SG) depletes the 2DEG in the channel and creates an energy barrier for electrons. During the blocking state, the depletion region gradually expands within the SG under high drain stress. Once the SG is fully depleted, the electron barrier in the channel is eliminated, allowing electron current to flow and consequent avalanche-like non-destructive breakdown. While this non-destructive breakdown exhibits similar electrical characteristics as the avalanche process, the SG-HEMT operates on a distinct physical mechanism. Instead of impact ionization and carrier multiplication, breakdown of the SG-HEMT is triggered by the full depletion of the SG, facilitating unipolar channel electron conduction. Thus, the well-designed SG-HEMT with an SG length of 9 μm exhibits a non-destructive breakdown voltage of ∼483 V, targeting 400 V applications. Moreover, the SG-HEMT shows no current degradation after ten cycles of repetitive breakdown tests. Meanwhile, owing to the suppression of trapping effects by the SG, an ultra-low dynamic RON/static RON ratio of 1.09 is achieved after 400 V stress. These results indicate that the SG-HEMT offers a promising pathway to construct highly robust GaN power systems.