【Domestic Papers】Theoretical Analysis of Vertical β-Ga₂O₃ Schottky Barrier Diodes With p-NiO Field Limiting Rings for High P-FOM Performance

      Researchers from the Fuzhou University have published a dissertation titled "Theoretical Analysis of Vertical β-Ga₂O₃ Schottky Barrier Diodes With p-NiO Field Limiting Rings for High P-FOM Performance" in IEEE Journal of the Electron Devices Society.

Project Support

      This work was supported by the Fund of Fujian Provincial Science and Technology Planning Project (No.2022I0006), the Fund of Young and Middle-aged Teacher Education Research Project of Fujian Provincial Department of Education (JAT220026), and the Fund of Science and Technology Major Project of Fujian Province (2022HZ027006).

Introduction

      The semiconductor material of Ga₂O₃​ has been widely studied due to its wide bandgap of 4.5-4.9 eV, estimated high critical breakdown electric field (E-field) of 8 MV/cm, and the Baliga’s figure of merit(BFOM=ɛμEC³) is yielded to be around 3000, which outperforms those of other wide bandgap materials such as GaN or SiC. Thus, β-Ga₂O₃​-based power devices have been highly sought after in the high-power community recently. However, due to the self-compensation effect of ntype background carriers in Ga₂O₃​ the lack of shallow level acceptor, and the large effective mass of holes have led to the absence of p-type β-Ga₂O₃​ so far. Therefore, most research attention is paid to unipolar devices, including field effect transistors (FET) and diodes. For diodes, it can be roughly divided into PN junction diode and SBD due to its construction mode. Compared to traditional PN junction diodes, SBD have lower Von and faster reverse recovery times, so them being commonly used as high-speed switching devices.

Abstract

      Power devices based on Ga₂O₃ have been widely studied in recent years. Due to the absence of the p-Ga₂O₃, the performance of the power devices based on Ga₂O₃ was largely limited. To get better performance, many Ga₂O₃ Schottky Barrier Diodes (SBD) with edge termination (ET) were proposed. In this work, p-NiO field limiting rings (FLRs) are implanted into Ga₂O₃ SBD to improve the power figure of merit (P-FOM) and reduce the complexity of the current high-performance edge termination structure manufacturing process. The implantation of the FLRs can weaken the peak electric field strength and extend the depletion zone in the horizontal direction. Further exploring the influence of some parameters of the device on device performance through TCAD simulation, the breakdown voltage (BV)/specific on-resistance (R_on,sp) of SBD with FLRs is up to 5340 V/3.748 mΩ·cm², and P-FOM = BV²/R_on,sp can reach 7.61 GW/cm², and turn-on voltage (V_on) of 0.9 V is achieved. The manufacturing process of the presented Ga₂O₃ SBD with p-NiO FLRs is relatively simple compared to devices with approximate P-FOM values. This kind of Ga₂O₃ SBD with FLRs has great promise for future high-power applications.

Conclusion

      This study proposes the structure of SBD with p-NiO FLRs to improve the P-FOM performance of the current SBD. It has also been found through analysis that in NiO/Ga₂O₃ SBD, the breakdown voltage strongly depends on parameters such as the doping concentration, thickness of NiO, the spacing and number of the FLRs, as well as the mode of spacing. BV/R_on,sp of 5340 V/3.748 mΩ·cm², and P-FOM of 7.61 GW/cm² were ultimately achieved. The good P-FOM performance of this device demonstrates the great potential of combining p-NiO in Ga₂O₃ power electronic devices.