【Member Papers】A Novel Electric field Modulation Ga₂O₃ Schottky Barrier Diode with Nitrogen-Ion Implantation combine with Trench Field Limit Rings and Floating Metal Rings Termination

      Researchers from University of Electronic Science and Technology of China, Suzhou Institute of Nano-Tech and NanoBionics, Chinese Academy of Sciences have published a dissertation titled "A Novel Electric field Modulation Ga₂O₃ Schottky Barrier Diode with Nitrogen-Ion Implantation combine with Trench Field Limit Rings and Floating Metal Rings Termination" in 2026 IEEE 38th International Symposium on Power Semiconductor Devices and ICs (ISPSD).

Background

      β-Ga₂O₃ is an ultra-wide bandgap semiconductor with a bandgap of about 4.8 eV and a critical breakdown electric field up to 8 MV/cm. Its Baliga's figure-of-merit is much higher than Si, GaN and SiC, making it highly promising for high-voltage and high-power electronic devices. Large-size and high-quality β-Ga₂O₃ single crystals can be grown by melt growth methods for low-cost mass production. Due to self-compensation and deep acceptor levels, effective p-type doping of β-Ga₂O₃ is difficult, so unipolar vertical Schottky barrier diodes are the main commercial solution. Various edge termination technologies have been developed to improve device performance. Ion implantation and trench field limit rings can effectively suppress edge electric field and leakage current. However, single termination structure has limitations in electric field modulation. It is urgent to develop composite termination structures to further improve the performance of Ga₂O₃ power diodes.

Abstract

      A novel electric field modulation Ga₂O₃ Schottky barrier diode (SBD), which integrates nitrogen-ion implantation (NI) guard rings, trench field limiting rings (TFLR), and floating metal rings (FMR), is reported in this work. The proposed design effectively modulates the electric field distribution by employing NI guard rings to suppress leakage current and reduce surface electric field. Furthermore, the integration of TFLR and FMR within the termination region provides additional electric field modulation, substantially enhancing the device's voltage-blocking capability. Compared with the conventional vertical Ga₂O₃ SBD, the proposed NI-TFMR SBD increases the breakdown voltage (BV) from 91V to 1768 V, while maintaining an ultra-low turn on voltage of ~ 0.7 V,a specific on-resistance of 5.72 mΩ・cm² and a high power figure-of-merit (PFOM) of 0.55 GW/cm² ,which is highest among all the previous ion-implantation termination vertical Ga₂O₃ SBDs. This work provides a new viable approach to the design and fabrication of vertical Ga₂O₃ SBDs.

Highlights

      A composite termination structure combining nitrogen-ion implantation guard rings, trench field limiting rings and floating metal rings is proposed for Ga₂O₃ SBD.

      The composite structure achieves excellent electric field modulation effect and greatly improves the breakdown voltage of the device.

      The device maintains low turn-on voltage and low specific on-resistance while realizing high breakdown voltage.

      The power figure-of-merit of the device reaches the highest level among similar ion-implantation terminated Ga₂O₃ SBDs.

Conclusion

      This work fabricated and compared three types of vertical SBDs with distinct termination structures: a reference device without termination, a device with only nitrogen-ion implantation (NI) termination, and the proposed device featuring the composite NI-trench-floating metal ring (NI-TFMR) termination. The introduced termination structures effectively modulate the electric field distribution, leading to a dramatic enhancement in blocking capability. The nitrogen implantation alone raises the breakdown voltage (BV) from 91 V to 1019 V (an 11 times increase). In contrast, the NI-TFMR SBD further pushes the BV to 1768 V, representing a 19.4 times improvement over the reference and a 73% increase over the NI SBD, while simultaneously achieving a low Rₒₙ.ₛₚ of 5.72 mΩ·cm². This yields a high PFOM of 0.55 GW/cm². The results validate the superior electric field modulation capability of the proposed NI-TFMR structure and demonstrate its strong potential for developing high-performance vertical Ga₂O₃ power devices.

Project Support

      This work was supported in part by the Central Guiding Local Science and Technology Development Special Project of Sichuan (2024ZYD0310).