Fast-Neutron Irradiation Effects on Gallium Oxide Schottky Diodes Fabricated on Sapphire Substrates
Researchers demonstrated that nickel/β-Ga₂O₃ Schottky barrier diodes grown on low-cost sapphire substrates remain operational after exposure to fast-neutron fluences up to 1×10¹⁵ n·cm⁻², a level relevant to space and nuclear environments. Neutron irradiation caused measurable changes including a doubling of turn-on voltage, a ~50% reduction in carrier concentration, and an increase in breakdown voltage from 101 to 135 V, attributed to neutron-induced donor compensation. The findings suggest that LPCVD-grown heteroepitaxial β-Ga₂O₃ on sapphire is a viable candidate for radiation-hard power electronics in demanding applications.
A study submitted to arXiv investigates how fast-neutron irradiation affects Ni/β-Ga₂O₃ Schottky barrier diodes fabricated via low-pressure chemical vapor deposition (LPCVD) on c-plane sapphire substrates. Before irradiation, devices showed a turn-on voltage of 1.20 V, specific on-resistance of 8.43 mΩ·cm², an ideality factor of 1.32, and a Schottky barrier height of 1.29 eV. After irradiation at a fluence of 1×10¹⁵ n·cm⁻², the turn-on voltage rose to 2.40 V and the barrier height increased slightly to 1.34 eV, while forward current decreased and net donor concentration fell by approximately 50%, corresponding to a carrier-removal rate of ~105 cm⁻¹. Notably, the breakdown voltage improved from 101 to 135 V, and reverse leakage current was significantly suppressed, both consistent with neutron-induced donor compensation. Temperature-dependent measurements from 25 to 250°C confirmed that thermionic emission remained the dominant transport mechanism throughout. TCAD simulations corroborated the experimental results, showing a more uniform electric-field distribution and reduced field crowding at the Schottky contact edge post-irradiation. The use of sapphire substrates rather than native β-Ga₂O₃ substrates lowers fabrication costs, making these results particularly relevant for scalable radiation-tolerant electronics.
What's missing
The study does not report long-term stability or annealing behavior after irradiation, leaving open whether radiation-induced defects and performance shifts are permanent or partially recoverable. The carrier-removal rate and breakdown improvement are characterized at a single fluence level; dose-response behavior across a broader fluence range is not established. Additionally, direct comparison with competing wide-bandgap semiconductors (e.g., SiC or GaN) under equivalent neutron conditions is absent, making relative radiation hardness difficult to assess.
What different sources said
- arXiv physicsCenter
Fast-Neutron Irradiation Effect in Heteroepitaxial $\beta$-Ga$_2$O$_3$ Schottky Diodes Fabricated on Low-Cost Sapphire Substrates
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