To improve the blocking performance of Ga2O3 Schottky barrier diode (SBD), based on the field strength distribution at the bottom of the trench and edge effect, the impacts of structure parameter on breakdown voltage and the figure of merit (FOM) were investigated by TCAD simulation and optimization. The results indicated that the breakdown voltage raised as the corner radius of trench R and the trench length K increased in a certain range, in which K was employed to optimize the structure with a minor mesa width W. In addition, Al2O3 was confirmed as an appropriate dielectric layer material in Ga2O3 SBD. When the structure parameters were W = 1 μm, R = 0.6 μm, K = 0.8 μm–0.9 μm and Al2O3 was selected as dielectric layer materials, a Ga2O3 trench SBD with breakdown voltage of 3.4 kV and the FOM of over 1.7 GW·cm−2 was proposed.
This study proposes a NiO/β-Ga2O3 etched heterojunction extension termination design for NiO/β-Ga2O3 PN diode to fulfill the application of 6 kV high-voltage with a considerably outstanding power figure of merit 10 GW/cm2, validated and optimized by sentaurus TCAD software. The results indicated the optimum termination parameters L=20mm and DJET=2.3×1013cm-2 for the single junction termination extension structure with 4000V breakdown voltage, and L1=L2=20mm, DJET1=4×1013cm-2 and DJET2=2.3×1013cm-2 for the double junction termination extension structure with 6000V. Moreover, to evaluate the power figure of merit of the optimized devices, the specific resistances were extracted from the forward characterizations with setting appropriate electron and hole mobility from experiment results, which exhibited a power figure of merit of 4.7 GW/cm2 for the single junction termination extension and 10 GW/cm2 for double junction termination extension. Meanwhile, utilizing the Poisson equation calculated the ideal one-dimension electric field at NiO/Ga2O3 interface in Ga2O3 for the optimized devices, the single junction termination extension with 5.3MV/cm at reverse 4000V, and 7.3MV/cm of the double junction termination extension incredibly approached Ga2O3 critical breakdown electric field of 8MV/cm at reverse 6000V, demonstrating our designed device structures possess immense potential for high-voltage power application.
A p-NiO/n-Ga2O3 heterojunction diode with positive bevel angle termination based on a complete wafer is proposed, verified, and optimized by TCAD. The results indicated the optimal angle of 78° for the positive bevel angle terminal, which reduces the peak surface electric field to 6 MV/cm and effectively avoids the premature breakdown of the terminal of the Ga2O3 layer. Further, the effect of each dielectric passivation on the terminal electric field was investigated, where SiO2 was determined to be the optimal passivation material to minimize the peak electric field on the side of the terminal. Ultimately, considering the effect of drift layer thickness on breakdown voltage (BV) and specific on-resistance (Ron·sp), the diode achieves BV up to 10 kV and optimal power figure of merit (PFOM) over 16.5 GW/cm2 when the drift layer thickness is 20 μm, which fully demonstrates the great potential of positively beveled terminal-optimized p-NiO/n-Ga2O3 heterojunction diodes for next-generation high-voltage and high-power applications.
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