High-Performance Vertical β-Ga2 O3 Schottky Barrier Diodes Featuring P-NiO JTE with Adjustable Conductivity

We demonstrate a novel conductivity-controlled junction termination extension (JTE) technique using p-type NiO – a key element for potential commercialization of Ga
2
O
3
power devices without common reliability concerns. The hole concentration of the NiO layer as JTE can be regulated by changing the gas atmosphere during sputtering growth, which can be precisely controlled to maximize the breakdown voltage $(V_{\mathrm{br}})$. The implementation of the JTE results in high-performance vertical $\beta -\mathrm{Ga}_{2} \mathrm{O}_{3}$ Schottky barrier diodes (SBDs), in which the reverse leakage is significantly suppressed, suggesting the effectiveness of p-NiO JTE in reducing fringe electric field. The $\beta -\mathrm{Ga}_{2} \mathrm{O}_{3}$ SBDs with an optimized hole concentration about $10 ^{17}\ \mathrm{cm}^{-3}$ in the JTE region exhibit a low specific on-resistance $(R_{\mathrm{on,sp}})$ of $2.9 \mathrm{m}\Omega \cdot \mathrm{cm}^{2}$ and a high $V_{\mathrm{br}}$ of 2.1 kV, yielding a high power figure-of-merit (PFOM) of 1.52 GW/cm
²
. In addition, a high forward current density of 180 A/cm
²
@2 V and a high breakdown voltage of 1.3 kV for $\beta -\mathrm{Ga}_{2} \mathrm{O}_{3}$ JTE-SBD with area of 0.78 mm
²
were achieved. These results demonstrate the great potential of p-NiO as a controllable and reliable technique for junction engineering in $\beta -\mathrm{Ga}_{2} \mathrm{O}_{3}$ power devices.