【Member Papers】Real-time evolution of performance in β-Ga₂O₃ Schottky barrier diodes under on-state stress

      Researchers from the Nanjing University of Posts and Telecommunications have published a dissertation titled "Real-time evolution of performance in β-Ga₂O₃ Schottky barrier diodes under on-state stress" in Applied Physics Letters.

Project Support

      This work was supported in part by the National Natural Science Foundation of China under Grant Nos. 62304113 and 62204126 and in part by the National Key R&D Program of China under Grant No. 2022YFB3605404.

Background

      Ultra-wide bandgap semiconductor β-Ga₂O₃ possesses a bandgap of up to 4.9 eV and a breakdown field of 8 MV/cm. This, coupled with its high Baliga’s figure of merit, positions β-Ga₂O₃ as a promising candidate for next-generation power electronic devices. The availability of cost-effective, large-scale β-Ga₂O₃ single crystal substrates further strengthens its candidacy for power applications. However, β-Ga₂O₃ faces the challenge of intrinsically low thermal conductivity. Low thermal conductivity can exacerbate degradation at the metal–semiconductor interface, which is a critical concern during high-power on-state operation, thereby undermining device reliability.

Abstract

      β-Ga₂O₃ is rapidly emerging as a leading material for next-generation high-power electronic devices due to its exceptional material properties, such as a high breakdown field and a superior Baliga's figure of merit. Vertical β-Ga₂O₃ Schottky barrier diodes (SBDs) offer advantages, including high on-current density and efficient chip area utilization; however, these benefits also result in elevated power density. Due to the low thermal conductivity of β-Ga₂O₃, the junction temperature during forward operation is potentially higher than that of SiC and GaN devices, which poses a greater challenge to its long-term reliability. A comprehensive understanding of the on-state reliability for the β-Ga₂O₃ SBDs is still lacking. Here, we address this gap by employing a measure–stress–measure approach to systematically investigate the real-time degradation and recovery behavior of key performance parameters—turn-on voltage (V_on) and on-resistance (R_on)—in the β-Ga₂O₃ SBDs. We subject these devices to prolonged forward bias stress (5–9 V) and varying temperature conditions (25–125 °C) to assess their degradation characteristics and mechanisms. Notably, at an operating temperature of 125 °C, these β-Ga₂O₃ SBDs are projected to function reliably for almost a decade at an operating voltage of 1.46 V, assuming a 5% shift in V_on as the failure criterion. This exceptional robustness, attributed to both the inherent material properties of β-Ga₂O₃ and the quality of the β-Ga₂O₃ Schottky interface, highlights the potential of β-Ga₂O₃ for long-term, high-performance applications in demanding power electronics.

Conclusion

      In conclusion, this study investigates the performance degradation and recovery mechanisms of vertical β-Ga₂O₃ SBDs under on-state stress, using an MSM technique. The research explores the impact of stress voltage and temperature on key parameters, including V_on and R_on. The results show that both stress voltage and temperature strongly influence the degradation, with higher voltages and temperatures accelerating the degradation and increasing the non-recoverable degradation. Analyses of the reverse leakage current, together with the STEM results, indicate that the non-recoverable degradation originates from alterations at the interface. The lifetime prediction using the MSM technique suggests that the devices could operate reliably for nearly a decade at a standard operating voltage and room temperature, demonstrating their potential as a promising material for next-generation power devices.