Fast-neutron irradiation response of β-Ga2O3 Schottky barrier diodes on sapphire substrate

In this work, we investigate the electrical response of Ni/β-Ga2O3 Schottky barrier diodes (SBDs) fabricated on c-plane sapphire substrates under fast-neutron irradiation at a fluence of 1 × 1015 n cm−2. The β-Ga2O3 heteroepitaxial device stack is grown by low-pressure chemical vapor deposition (LPCVD) and comprises a 1.05 μm unintentionally doped buffer, a 2.10 μm n+ layer (ND,n+ ≈ 1 × 1019 cm−3), and a 3.15 μm drift layer (ND,drift ≈ 2.07 × 1017 cm−3), with plasma-free mesa definition achieved by Ga-assisted LPCVD-based etching. Prior to irradiation, the devices exhibit a turn-on voltage of 1.20 V, minimum differential specific on-resistance Ron,sp = 8.43 mΩ cm2, ideality factor η = 1.32, and a Schottky barrier height of 1.29 eV. Even after exposure to a high 1 MeV equivalent fast-neutron fluence of 1 × 1015 n cm−2, the devices remain operational, although the forward current decreases, the turn-on voltage increases to 2.40 V, and minimum Ron,sp rises to 8.85 mΩ cm2. Simultaneously, the barrier height increases to 1.34 eV and the net donor concentration in the drift layer decreases by ∼46% to 1.12 × 1017 cm−3, corresponding to a carrier-removal rate of ∼95 cm−1. Temperature-dependent measurements from 25 to 250 °C confirm that thermionic emission remains the dominant transport mechanism and show a systematic suppression of reverse leakage. The breakdown voltage increases from 101 to 135 V, accompanied by a reduction in the estimated peak electric field from 2.75 to 2.34 MV cm−1, consistent with neutron-induced drift-layer compensation. Silvaco two-dimensional technology computer-aided design simulations reveal that the electric field becomes more uniformly distributed over a wider depletion region, reducing field crowding at the Schottky edge. The measured behavior offers critical insight into neutron-induced donor compensation in β-Ga2O3 films grown on non-native substrates and demonstrates the potential of heteroepitaxial β-Ga2O3 SBDs to maintain stable operation under high-fluence neutron environments relevant to space and nuclear electronics.