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This work demonstrates quasi-vertical β-Ga2O3 Schottky barrier diodes (SBDs) fabricated on c-plane sapphire substrates using an all-low-pressure chemical vapor deposition (LPCVD)-based, plasma-free process flow that integrates both epitaxial growth of a high-quality β-Ga2O3 heteroepitaxial film with in situ Ga-assisted β-Ga2O3 etching. A 6.3 μm thick (2̄01) oriented β-Ga2O3 epitaxial layer structure was grown on c-plane sapphire with 6° miscut, comprising a moderately Si-doped (2.1 × 1017 cm−3) 3.15 μm thick drift layer and a heavily doped (1 × 1019 cm−3) contact layer on an unintentionally doped buffer layer. Mesa isolation was achieved via Ga-assisted plasma-free LPCVD etching, producing ∼60° inclined mesa sidewalls with an etch depth of 3.6 μm. The fabricated SBDs exhibited excellent forward current–voltage characteristics, including a turn-on voltage of 1.22 V, an ideality factor of 1.29, and a Schottky barrier height of 0.83 eV. The minimum differential specific on-resistance was measured to be 8.6 mΩ cm2, and the devices demonstrated high current density capability (252 A/cm2 at 5 V). Capacitance–voltage analysis revealed a net carrier concentration of 2.1 × 1017 cm−3, uniformly distributed across the β-Ga2O3 drift layer. Temperature-dependent J–V–T measurements, conducted from 25 to 250 °C, revealed thermionic emission-dominated transport with strong thermal stability. The Schottky barrier height increased from 0.80 to 1.16 eV, and the ideality factor rose modestly from 1.31 to 1.42 over this temperature range. Reverse leakage current remained low, increasing from ∼5 × 10−6 A/cm2 at 25 °C to ∼1 × 10−4 A/cm2 at 250 °C, with the Ion/Ioff ratio decreasing from ∼1 × 107 to 5 × 105. The devices achieved breakdown voltages ranging from 73 to 100 V, corresponding to parallel-plate electric field strengths of 1.66–1.94 MV/cm. These results highlight the potential of LPCVD-grown and etched β-Ga2O3 devices for high-performance, thermally resilient power electronics applications. 

A systematic investigation of the electrical characteristics of β-Ga2O3 Schottky barrier diodes (SBDs) has been conducted under high-dose 60Co gamma radiation, with total cumulative doses reaching up to 5 Mrad (Si). Initial exposure of the diodes to 1 Mrad resulted in a significant decrease in on-current and an increase in on-resistance compared to the pre-radiation condition, likely due to the generation of radiation-induced deep-level acceptor traps. However, upon exposure to higher gamma radiation doses of 3 and 5 Mrad, a partial recovery of the device performance occurred, attributed to a radiation annealing effect. Capacitance–voltage (C–V) measurements showed a decrease in net carrier concentration in the β-Ga2O3 drift layer, from ∼3.20 × 1016 to ∼3.05 × 1016 cm−3, after 5 Mrad irradiation. Temperature-dependent I–V characteristics showed that 5 Mrad irradiation leads to a reduction in both forward and reverse currents across all investigated temperatures ranging from 25 to 250 °C, accompanied by slight increases in on-resistance, ideality factors, and Schottky barrier heights. Additionally, a slight increase in reverse breakdown voltage was observed post-radiation. Overall, β-Ga2O3 SBDs exhibit high resilience to gamma irradiation, with performance degradation mitigated by radiation-induced self-recovery, highlighting its potential for radiation-hardened electronic applications in extreme environment.