【Device Papers】Enhanced breakdown voltage in β-Ga₂O₃ Schottky diodes via fast neutron irradiation and electro-thermal annealing

      Researchers from the University of Massachusetts Lowell have published a dissertation titled "Enhanced breakdown voltage in β-Ga₂O₃ Schottky diodes via fast neutron irradiation and electro-thermal annealing" in Applied Physics Letters.

Abstract

      This study demonstrates a substantial enhancement of breakdown voltage in β-Ga₂O₃ Schottky barrier diodes through an approach that combines fast neutron irradiation with controlled post-irradiation electro-thermal annealing. Devices irradiated with 1 MeV neutrons at a high fluence of 1 × 10¹⁵ n/cm² initially exhibited substantial degradation, including a drastic reduction in on-current and an increase in on-resistance. Electro-thermal testing, conducted through simultaneous current–voltage measurements while heating the devices up to 250 °C, resulted in significant recovery. After four cycles of electro-thermal testing, the devices demonstrated significant improvements in performance, with a substantial recovery of on-current and a reduction in on-resistance compared to the post-radiation condition, approaching pre-radiation levels. Most recovery occurred during the first two cycles, with diminishing improvements thereafter, indicating that thermally responsive radiation-induced traps were largely mitigated early in the process. Capacitance–voltage measurements revealed a substantial reduction in net carrier concentration, decreasing from 3.2 × 10¹⁶ cm⁻³ pre-radiation to 5.5 × 10¹⁵ cm⁻³ after the first electro-thermal testing cycle, indicating an over 82% reduction. Following the third cycle, the carrier concentration partially recovered to 9.9 × 10¹⁵ cm⁻³, reflecting a carrier removal rate of ∼22 cm⁻¹. The breakdown voltage (V_br) exhibited a remarkable enhancement, increasing from approximately 300 V to 1.28 kV (a ∼325% improvement) after the first electro-thermal testing, which can be attributed to the reduction in net carrier concentration by compensating radiation-induced traps. Subsequent testing reduced V_br slightly to 940 V due to partial recovery of carrier concentration, but it remained significantly higher than pre-radiation levels. These findings demonstrate the potential of combining neutron irradiation with electro-thermal annealing to significantly enhance the voltage-blocking capability of β-Ga₂O₃ power devices, making them strong candidates for high-power applications in radiation-intense environments.

DOI：

https://doi.org/10.1063/5.0297242