Balancing Threshold Voltage and On-Resistance of p-GaN Gate HEMTs via Mg Doping Engineering

Mg out-diffusion during epitaxial growth in MOCVD chambers poses significant challenges in simultaneously achieving a decent threshold voltage ${V}_{\text {TH}}$ and on-resistance ${R}_{\text {ON}}$ . In this work, by inserting a GaN layer with thickness ${t}_{\text {GaN}}$ of 0/5/10 nm between the p-GaN cap and the AlGaN barrier to tune the Mg profile, we found that: 1) the forward gate leakage current of p-GaN gate high-electron-mobility transistors (HEMTs) was independent of ${t}_{\text {GaN}}$ ; 2) excessive Mg diffusion into the barrier and channel layer of the HEMTs without this GaN insertion layer severely jeopardized stability; 3) HEMTs with ${t}_{\text {GaN}}$ of 5-nm achieved balanced ${V}_{\text {TH}}$ of 2.25 V, ${R}_{\text {ON}}$ of $9.04~\Omega \cdot $ mm, and off-state leakage current as low as $10^{-{8}}$ A/mm at 650 V; and 4) Mg doping engineering successfully kept the dynamic ${R}_{\text {ON}}$ degradation within $1.2\times $ under high-voltage off-state stress and ${V}_{\text {TH}}$ shift by 0.1 V under bias-temperature instability (BTI) stress. These results indicate that dedicated tailoring of the Mg doping profile in the p-GaN layer can achieve high ${V}_{\text {TH}}$ and low ${R}_{\text {ON}}$ simultaneously, offering a practical approach to enhance the performance and reliability of p-GaN gate HEMTs.