Shaozhong Yue

In this Letter, the performance degradation mechanisms of β-Ga2O3 heterojunction diodes (HJDs) under 10 MeV proton irradiation have been investigated. After proton irradiation with a fluence of 1 × 1013 p/cm2, the forward current density (JF) decreased by 9.9%, the specific on-resistance (Ron, sp) increased from 16.2 to 18.0 mΩ cm2, and the breakdown voltage (Vbr) increased by approximately 310 V. The results of the electrical stress test indicate that the JF of HJDs gradually decreases as the duration of the applied electrical stress increases. Low-frequency noise measurements were carried out in order to characterize the defects introduced into the HJDs after proton irradiation. Meanwhile, to further elucidate the underlying damage mechanism of HJDs, the effect of proton irradiation on the trap states was also studied using frequency-dependent conductivity (Gp/ω) techniques. The results indicate that the density of trap states at NiO/β-Ga2O3 increases from 2.08–9.78 × 1011 cm−2 eV−1 to 1.25–2.87 × 1012 cm−2 eV−1, accompanied by a slight increase in trap activation energy from 0.0042–0.061 to 0.0265–0.075 eV after 10 MeV proton irradiation. The research outcomes provide an important theoretical reference for evaluating the space radiation tolerance of Ga2O3-based power diodes.

Electron-irradiated lateral double-diffused metal oxide semiconductor (LDMOS) devices are found to suffer from severe additional degradation when subjected to a current-limited overvoltage stress, whose level is considered safe for fresh power devices. With a fluence of 1 × 1016 cm−2 10 MeV electrons, the linear-region saturation current (Idsat) drops by 82.6% after irradiation. A subsequent overvoltage stress with 1 μA current limit causes a 6.0 μA decrease in Idsat for the irradiated device, while the same stress on a fresh device reduces Idsat by only 2.8 μA. The synergistic degradation is accompanied by increased subthreshold swing, reduced transconductance, and a positive threshold voltage shift. In contrast, the saturation-region current shows much weaker synergy. Technology Computer-Aided Design (TCAD) simulations suggest the synergistic effect of irradiation-induced bulk defects and interface states, these enhance trap-assisted carrier injection under high electric fields, contributing to the generation of interface states near the gate oxide and channel region. These results reveal that conventional overcurrent protection may not guarantee the reliability of irradiated LDMOS devices, calling for coupled irradiation-overvoltage qualification tests.

In this work, the synergistic effect of 5 MeV proton irradiation and different biases on the electrical performance of a β-Ga2O3 Schottky barrier diode was studied. Experimental results demonstrate that proton irradiation leads to significant degradation in electrical performance with increasing proton fluence, manifested as decreased forward current density, reduced reverse current density, and increased breakdown voltage. Based on deep-level transient spectroscopy and capacitance–voltage measurements, the degradation is attributed to the introduction of an electron trap at the energy level of EC-0.75 eV (gallium vacancy-related defect) within the drift layer during irradiation. Furthermore, the introduction of an off-state bias during proton irradiation results in more severe degradation of the electrical performance of the device relative to the case of proton irradiation without bias. Molecular dynamics simulations and theoretical analysis reveal that this enhancement in degradation is attributed to the applied electric field that suppresses the recombination of gallium vacancies–interstitial atoms and elevates the energy of low-energy secondary particles, thereby promoting the formation of gallium vacancy-related defects.

This study investigates the impact of 60Co γ-ray irradiation on the gate leakage mechanism of Schottky-type p-GaN gate AlGaN/GaN HEMTs. Devices with breakdown voltage of 650 V were irradiated with 60Co γ-ray at a gate bias of VG_stress = 7 V. A significant increase in the forward gate current was observed with increasing irradiation dose. To analyze the gate leakage mechanisms before and after irradiation, temperature-dependent current–voltage (IG–VG) measurements and capacitance deep-level transient spectroscopy were performed. The results indicate that under reverse gate bias, the leakage mechanism consistently remains trap-assisted tunneling (TAT) both before and after irradiation. However, under forward gate bias, the dominant conduction mechanism shifts from Poole–Frenkel emission to TAT as a result of the introduction of hole traps with an energy level of EV + 0.93 eV.

In this work, we study the electrical performance of AlGaN/GaN high-electron-mobility transistors following irradiation with 14 MeV neutrons at fluences of 3 × 1012, 7.4 × 1012, 1.2 × 1013, and 1.0 × 1014 n/cm2. The results reveal that at a neutron fluence of 7.4 × 1012 n/cm2, there is a notable increase in the saturation drain current, a negative shift in threshold voltage, and an enhancement in peak transconductance. As the fluence continues to increase, the electrical characteristics of the device begin to deteriorate. However, at a fluence of 1.0 × 1014 n/cm2, the electrical performance is still better than that before irradiation. The defect evolution induced by neutron irradiation is studied by utilizing low-frequency noise (LFN) and deep-level transient spectroscopy (DLTS) techniques. LFN analysis shows only slight changes in interface state density, while DLTS results reveal a significant reduction in deep-level defects after irradiation. We speculate that bulk defects in the GaN or AlGaN layers predominantly influence device performance variations. Neutron irradiation facilitates the recombination of original defects, thereby decreasing the concentration of deep-level defects in the device. This decrease in deep-level defects alleviates carrier trapping by defects, resulting in an increased carrier concentration and improved electrical performance of the device.

In view of the lower thermal conductivity of β-Ga₂O₃, effective heat dissipation is crucial for maintaining its high output power and reliability. This study presents an active thermal management model for β-Ga₂O₃ Schottky barrier diodes (SBDs) using thermoelectric coolers (TECs), employing both experimental and numerical methods. The heat generated by the SBD can be effectively dissipated to the surroundings through the Peltier effect in thermoelectric (TE) materials. Experimental results show that, with a TEC input current of 6 A, the case temperature remains below 25 ^∘C even at an SBD output power of 25 W, achieving a maximum junction temperature reduction of 74.5 ^∘C compared to when the TEC is off. At a TEC input current of 3 A, the net output power of the SBD reaches 11.8 W, corresponding to an improvement ratio of 36.9%. In simulation, TEC parameters are analyzed to optimize the junction temperature. For every 0.1-mm reduction in the height of TE legs, the junction temperature decreases by 5.3 ^∘C. The Seebeck coefficient significantly impacts the junction temperature through co-optimization of material parameters. This work provides guidance for designing and optimizing the thermal management of β-Ga₂O₃ SBDs with TECs.

This study explores the impact of constant forward electrical stress on beta-gallium oxide (β-Ga2O3) Schottky barrier diodes (SBDs) from the prospective of defect evolution. Prolonged stress significantly increased the reverse leakage current density (JR) and forward current density (JF) under small bias and decreased the turn-on voltage (Von). Temperature-dependent current-voltage (I-V-T) analysis revealed that the reverse leakage current is dominated by Poole-Frenkel (PF) emission in both fresh and stressed SBDs, while the forward current transport mechanism transforms from thermionic emission (TE) to trap-assisted tunneling (TAT) after stress. Deep-level transient spectroscopy (DLTS) results identified an intrinsic trap E2* (EC - 0.75 eV) within the β-Ga2O3 drift layer, which is likely a Ga vacancy-related trap. The consistency of this energy level with the PF barrier proves that the increase in this trap is the main reason for the increase in JR. The spatial distribution features that the increase in trap concentration near the metal-semiconductor interface is much larger than that inside the bulk, which establishes the association between this trap and JF under small bias and Von. These findings highlight the critical role of trap evolution in SBD performance degradation under electrical stress.

The single event burnout (SEB) of beta-phase gallium oxide ( $\beta $ -Ga $_{\text{2}}$ O $_{\text{3}}$ ) Schottky barrier diode (SBD) under 205 MeV germanium (Ge) ions irradiation has been studied systematically in this work. A typical SEB phenomenon was observed when the bias voltage reached 190 V. Technology computer-aided design (TCAD) simulation was used to explore the possible burnout mechanism. The local high lattice temperature peak induced by the impact ionization under a high electric field was proposed to explain the permanent damage. The incident-heavy ions will generate the electron-hole pairs along the incidence tracks, which gain enough energy with the aid of the high longitudinal electric field. The high-energy carriers will trigger severe impact ionization, resulting in large current density and noticeable heat accumulation along the ion track. When the local lattice temperature exceeds the melting-point temperature of $\beta$ -Ga $_{\text{2}}$ O $_{\text{3}}$ material, it will gradually lead to thermal damage and SEB will be triggered. Utilizing the scanning electron microscope (SEM), it is evidently observed that the burnout area crosses through the entire $\beta $ -Ga $_{\text{2}}$ O $_{\text{3}}$ drift layer, which verifies the SEB mechanism. This research offers significant theoretical and experimental insights for evaluating the reliability of Ga $_{\text{2}}$ O $_{\text{3}}$ -based power devices against SEB in aerospace applications.

This work thoroughly investigates the effects of proton irradiation on the electrical performances of the AlGaN/GaN high-electron-mobility-transistors (HEMTs), especially on RF, OFF-state drain–source breakdown, and thermal characteristics. RF output power ( $\textit{P}_{\text{out}}$ ) and gain decrease after proton irradiation at higher input power. Degraded $\textit{P}_{\text{out}}$ further leads to a reduced power added efficiency (PAE). Moreover, irradiated devices exhibit an increased thermal resistance ( $\textit{R}_{\text{TH}}$ ). Contrary to the degraded dc, RF, and thermal characteristics, an improvement in OFF-state drain–source breakdown voltage (BV $_{\text{DS}}$ ) is observed after proton irradiation. Combined with the trap characterization results, it can be concluded that the degradation in dc and RF characteristics and the improvement in BV $_{\text{DS}}$ are related to the proton-induced generation of the acceptor traps with energy levels of $\textit{E}_{\text{C}}$ -0.56 eV and $\textit{E}_{\text{C}}$ -0.94 eV in and near the channel in the GaN layer and with an energy level of $\textit{E}_{\text{C}}$ -0.97 eV in the AlGaN layer. Further discussions indicate that the traps generated in the GaN layer and SiC substrate after proton irradiation can contribute to the increase in $\textit{R}_{\text{TH}}$ .