【Member Papers】3.23 GW/cm² power figure of merit and 0.69 V turn-on voltage β-Ga₂O₃ heterojunction barrier Schottky diodes with p-i-n junction termination

      Researchers from the Xidian University have published a dissertation titled "3.23 GW/cm² power figure of merit and 0.69 V turn-on voltage β-Ga₂O₃ heterojunction barrier Schottky diodes with p-i-n junction termination " in Science China-Information Sciences.

Background

      Owing to its ultrawide bandgap and high critical breakdown electric field, β-Ga₂O₃ holds great potential for high-voltage power electronic devices. However, the lack of reliable p-type β-Ga₂O₃ restricts the development of high-performance homojunction bipolar devices. Accordingly, fabricating heterojunctions between p-type oxides (especially NiOₓ) and n-type β-Ga₂O₃ has become a feasible approach to boost device performance. For β-Ga₂O₃ heterojunction barrier Schottky (HJBS) diodes, an inherent trade-off exists between breakdown voltage (BV) and turn-on voltage (Vₒₙ): improving voltage blocking capability generally requires a higher effective barrier height, which inevitably increases forward conduction loss. To address this dilemma, acceptor doping is proposed to modulate the Fermi level for enhanced blocking capability without a substantial rise in Vₒₙ. Nitrogen (N) doping has been proven to form a current-blocking layer in β-Ga₂O₃ devices. Moreover, theoretical calculations reveal that co-doping with two impurities enables more efficient electronic-structure modulation than single-impurity doping. Inspired by these findings, this work incorporates a p-i-n junction termination structure realized via N/P co-doping in NiOₓ/β-Ga₂O₃ HJBS diodes. Together with a p-NiOₓ termination ring, this design creates an internal junction with charge-compensation effects at the anode edge. Such a structure tailors the local electric field distribution and mitigates edge electric field crowding. As a result, the breakdown voltage is improved while low forward Vₒₙ and on-resistance (Rₒₙ) are maintained, achieving synergistic enhancement of voltage blocking capability and conduction efficiency.

Abstract

      β-Ga₂O₃ has attracted extensive interest for high-voltage power electronics owing to its ultra-wide bandgap and high critical electric field. However, the lack of reliable p-type β-Ga₂O₃ fundamentally restricts the realization of high-performance bipolar devices. Heterojunction structures employing p-type oxides,particularly NiO_x, provide a feasible pathway, yet they often suffer from a trade-off between breakdown voltage（BV） and turnon voltage(V_on). 

Conclusion

      In summary, NiO/β-Ga₂O₃ HJBS diodes incorporating an N/P co-doped p-i-n termination were demonstrated. The compensated implantation region effectively enhances voltage blocking capability while preserving low forward conduction loss. The devices achieve a BV of 3.9 kV and an R_on,sp of 4.75 mΩ·cm², corresponding to a P-FOM of 3.23 GW/cm². Additionally, stable electrical characteristics up to 150°C indicate robust thermal performance. These results provide an effective strategy for simultaneously improving breakdown capability and conduction efficiency in β-Ga₂O₃ power devices.

Project Support

      This work was supported by National Natural Science Foundation of China (Grant Nos. 62222407, 62421005) and Guangdong Basic and Applied Basic Research Foundation (Grant No. 2023B1515040024).