Zhangang Zhang

Hydrogen-terminated diamond field-effect transistors (H-diamond FETs) are promising for space electronics because of their high breakdown field, thermal stability, and radiation tolerance. However, their response to proton irradiation and the associated degradation mechanisms remain insufficiently understood. Here, depletion-mode H-diamond FETs are irradiated with 5 MeV protons at fluences of 1 × 1011, 1 × 1012, and 1 × 1013 p/cm2. At the highest fluence, the on-state current evaluated at a fixed gate overdrive decreases by approximately 43%, the peak transconductance decreases from 7.74 to 2.77 mS/mm, the subthreshold swing increases from 300 to 960 mV/dec, the gate leakage current increases by approximately four orders of magnitude, and the 99% current-stabilization time increases from 0.84 to 4.56 ms. Capacitance–voltage measurements reveal a positive flatband voltage shift consistent with radiation-induced negative trapped charge. Gate-controlled deep-level transient spectroscopy identifies three hole trap states at ET − EV = 0.354, 0.462, and 0.662 eV, including two states that emerge after irradiation and one preexisting state enhanced by irradiation. These results support two coupled degradation pathways: gate-stack ionization damage primarily affects threshold voltage, leakage, subthreshold behavior, and carrier stabilization, whereas displacement-related defects in diamond are associated with mobility and transconductance degradation.

Hydrogen-terminated diamond field-effect transistors (H-diamond FETs) are promising for radiation-tolerant electronics, but the response of the Al2O3/H-diamond gate stack to swift heavy ions remains insufficiently understood. Here, H-diamond FETs were irradiated with 1260 MeV Kr+ ions at fluences ranging from 1 × 106 to 1 × 108 ions/cm2 under different gate-bias conditions. DC, gate leakage, C–V, transient, and deep-level transient spectroscopy (DLTS) measurements were performed to evaluate device degradation. As the fluence increased, the threshold-voltage shift (ΔVth) increased from 2.50 ± 0.17 to 11.50 ± 0.51 V, while the relative transconductance reduction increased from 19.51% ± 1.12% to 65.16% ± 0.60%. At 1 × 108 ions/cm2, the subthreshold swing increased from approximately 0.240 to 0.400 ± 0.014 V/dec, and the 90% rise time increased from 0.24 to 0.44 ms. Degradation was more pronounced under positive gate bias during irradiation, suggesting field-assisted charge trapping. The increased gate leakage, C–V distortion, and 3.7-fold enhancement of the DLTS signal are consistent with irradiation-induced trapped charge and electrically active defects in the gate stack. These results identify gate-dielectric charge stability and Al2O3/H-diamond interface quality as key targets for radiation hardening.

We report a two-regime degradation behavior in NiO/β-Ga2O3 heterojunction diodes subjected to 1864 MeV Ta swift heavy ions (linear energy transfer in Si ≈ 75 MeV cm2/mg) over a fluence range from 1 × 108 to 1 × 1011 ions/cm2. At low fluences (≤1 × 109 ions/cm2), the devices retain rectification while exhibiting reduced forward current density (JF), increased specific on-resistance (Ron,sp), and enhanced reverse leakage current (JR), consistent with donor compensation in the β-Ga2O3 drift layer. Capacitance–voltage (C–V) analysis reveals a monotonic reduction in the net carrier concentration (Nnet) with carrier-removal rates (Rc) on the order of 107 cm−1, indicating a quasi-linear compensation regime. When the fluence approaches 1 × 1010 ions/cm2, rectification collapses and normal turn-on behavior is lost. The capacitance becomes weakly voltage dependent, suggesting deviation from linear compensation. Cross-sectional scanning transmission electron microscopy reveals densely distributed nanoscale latent tracks in the drift layer, while cross-sectional scanning electron microscopy shows pronounced ∼2 μm interfacial warping near the NiO/β-Ga2O3 junction. These results indicate a transition from a low-fluence quasi-linear carrier-compensation regime to a high-fluence failure regime associated with structural instability, where severe carrier compensation and failure-associated structural perturbations are both observed.

This study investigates the mechanism of single-event burnout (SEB) in NiO/β-Ga2O3 heterojunction diode (HJD) induced by atmospheric neutron. The degradation mode and physical mechanism are evaluated through current–voltage (I–V) measurement, emission microscopy, technology computer-aided design (TCAD), focused ion beam (FIB), and scanning electron microscopy (SEM) analysis. The experimental results indicate that the reverse bias voltage is a critical factor influencing SEB failure of NiO/β-Ga2O3 HJD. SEB occurs when the reverse bias reaches 750 V, characterized by a sharp increase in cathode current and catastrophic failure. Electrical characterization after SEB shows complete loss of rectifying behavior and reverse voltage withstand capability. TCAD simulations indicate that secondary particles generated by neutron interactions produce electron–hole pairs along their trajectory, which accelerate under the strong electric field in the drift layer, triggering impact ionization and current surge. Intense impact ionization leads to lattice temperature exceeding the melting point of β-Ga2O3, causing thermal runaway and burnout. FIB and SEM analysis confirms melt voids spanning the entire drift layer and part of the substrate, consistent with simulation results. These findings clarify the SEB mode and mechanism in NiO/β-Ga2O3 HJD and provide insights for evaluating their performance in harsh radiation environments.

This study investigates the impact of hydrogen treatment on the electrical performance and interface states of Ni/Au (001) $\beta $ -Ga₂O₃ Schottky barrier diode (SBD). Experimental results show that after 168 h of hydrogen treatment at $100~^{\circ }$ C, the Schottky barrier height ( $\Phi _{{B}}\text {)}$ decreases from 1.09 to 1.03 eV, the ideality factor ( ${n}\text {)}$ decreases from 1.14 to 1.07, and the forward current density ( ${J}_{{F}}\text {)}$ increases by 20.2%. These performance improvements are attributed to hydrogen-induced passivation of interface traps, as demonstrated by low-frequency noise (LFN) and frequency-dependent conductance analysis. In addition, secondary ion mass spectrometry (SIMS) results reveal a significant increase in hydrogen concentration at the Ni/Ga₂O₃ interface after hydrogen treatment. Hydrogen atoms react with unsaturated chemical bonds, forming stable covalent bond structures through electron pair sharing, thereby reducing the trap state density and trap activation energy. These findings provide valuable insights into hydrogen treatment as an effective method for optimizing the electrical performance of $\beta $ -Ga₂O₃ SBD.

This study investigates the displacement damage in β-Ga₂O₃ Schottky barrier diodes (SBDs) under different neutron fluences using a 14-MeV neutron irradiation source. The electrical performance of the devices before and after irradiation was evaluated through direct current–voltage (I–V) and capacitance–voltage (C–V) measurements. The results show that as the irradiation fluence increases, the forward current density of the device decreases, while the reverse current density and leakage current density increase, indicating that the degradation of the device intensifies with higher irradiation fluence. By employing frequency-dependent conductance techniques and deep-level transient spectroscopy (DLTS), changes in the bulk defect concentrations before and after irradiation were analyzed. It was found that the primary cause of device performance degradation is the increase in bulk defect concentrations related to oxygen vacancies induced by neutron irradiation. These findings were further validated through 2-D numerical simulations using technology computer-aided design (TCAD) tools, providing significant theoretical insights and experimental data to enhance the reliability and optimize the design of such devices.

This study investigates single-event burnout (SEB) effects in β-Ga2O3 Schottky barrier diodes under heavy ion irradiation. Bi, Ta, and Kr ions with linear energy transfer (LET) values of 99.7, 75, and 37 MeV/(mg·cm2), respectively, were used in the experiments. The results show that the SEB threshold voltage decreases with increasing LET, indicating a strong dependence on energy deposition. In addition, reverse bias is identified as a critical triggering condition for SEB, which occurs only when the applied voltage is high enough to initiate thermal runaway and cause irreversible damage. To further elucidate the failure mechanism, Kr ions were selected for detailed investigation. technology computer-aided design simulations combined with scanning electron microscopy-based failure analysis revealed that transient current surges can rapidly elevate the local temperature. Once the temperature reaches the melting point of Ga2O3 material, SEB is triggered by irreversible thermal failure. Moreover, the failure sites were primarily located at the edge of the Schottky junction, indicating structural vulnerability in this region. These findings clarify the LET and reverse bias dependence of SEB in ultra-wide bandgap devices and provide insights into radiation-hardened design.