Enhanced Gate Breakdown in β-Ga2O3HJFET through a NiOx/GaOxp-n Junction Gate Stack

In this work, we explore a novel structure of p-n herterojunction field-effect transistors (PN-HJFETs) to enhance gate breakdown characteristics. A sputtering n- $\text{GaO}_{\mathrm{x}}/\mathrm{p}-\text{NiO}_{\mathrm{x}}$ stack was featured as the gate of PN-HJFETs, showing improved gate breakdown capability. Schottky HJFETs (S-HJFETs) were fabricated as comparisons with PN-HJFET. Results demonstrate that PN-HJFETs exhibit ultra-low threshold voltage shifts, significantly small gate leakage, and enhanced forward gate breakdown voltage, surpassing the performance of S-HJFET. Moreover, PN-HJFETs exhibit excellent stability at high temperatures. Mechanism analysis suggests a hopping mechanism prevailing in low voltage regions and Poole Frenkel emission dominating in relatively high voltage region. Output characteristics and breakdown voltage measurements further validate the efficacy of HJFETs. Overall, the fabricated PN-HJFET structure shows promising potential for high-power and high-frequency switching applications.