This work demonstrates the heteroepitaxial growth of single-phase β -(Al x Ga 1− x ) 2 O 3 on (010) β -Ga₂O₃ substrates via metalorganic chemical vapor deposition, achieving an aluminum composition of up to 22.6% with no phase segregation characterized by x-ray diffractometer. The surface morphology of epitaxial layer becomes rougher initially and then smoother with the increase of Al composition, suggesting that the rising Al composition leads to changes in the epitaxial growth mode. The fabricated MOSFETs based on β -(Al 0.09 Ga 0.91 ) 2 O 3 epitaxial film achieve an ultra-high breakdown voltage over 3000 V and a high average breakdown field of 2.3 MV cm −1 . This work underscores the potential of β -(Al x Ga 1− x ) 2 O 3 heteroepitaxy technique and showcases its suitability for high-voltage power device applications.

In this article, a beta-gallium oxide (beta-Ga2O3)-based enhancement-mode (E-mode) FinFET is proposed, in which the combination of the Fin channels and recessed gate enables synergistic regulation of the threshold voltage and gate breakdown voltage. The device exhibits a threshold voltage(VTH) of + 0.4 V, a gate overdrive voltage up to 14.6 V, and a current density of 243 mA/mm. By employing heavily doped source/drain regions, an ohmic contact resistance as low as 0.76 Omega & sdot; mm and a specific on-resistance (Ron,sp) of 1.73 m Omega & sdot; cm(2) are achieved. Furthermore, comprehensive small-signal RF measurements are performed, based on which an accurate equivalent circuit model is established through systematic fitting and parameter extraction. The extracted intrinsic and parasitic parameters enable quantitative analysis of the factors limiting the high-frequency performance, yielding fT/fMAX values of 1.5-3.5 GHz for the beta-Ga2O3-based E-mode FinFET.

Interfacial and internal traps are the main factors limiting the performance and reliability of Ga2O3 Schottky barrier diodes (SBDs). Herein, the trap characteristics of Ga2O3 SBDs are investigated using the current transient method, elucidating the carrier trapping and detrapping processes. Under the forward and negative voltage stress, different traps can capture electrons from various sources. The test results show that there are five different types of electronic traps in the Ga2O3 device, and each trap corresponds to a different time constant, activation energy, and location. The activation energies of these traps are 0.089, 0.2, 0.81, and 0.95 eV, respectively. In addition, there exists a temperature-independent electronic trap whose behavior may be related to the direct tunneling process. Therefore, this method can be applied to the reliability study of Ga2O3 to achieve nondestructive characterization of Ga2O3 SBD traps.

This work demonstrates a significant advancement in high-power p-NiO/ beta -Ga2O3 heterojunction diode (HJD) technology. A large-area ( 2x 2 mm(2)) HJD is fabricated, achieving a remarkable combination of a 2870-V breakdown voltage (BV) and a 20-A forward current. This performance is enabled by a novel terminal structure incorporating a double-layered p-NiO film. The device exhibits a low specific on-resistance ( R-on,R-sp)of 14.4 m Omega center dot cm(2), yielding a high Baliga's power figure of merit (P-FOM) of 572 MW/cm(2) (calculated as P-FOM = BV2/ R-on,R- sp) . Furthermore, it displays excellent fast-switching characteristics, with an ultrashort reverse recovery time of 12.80 ns and a low reverse recovery charge of 19.70 nC. The surge current capability is confirmed to be 16 A at a voltage of 11.1 V. Temperature-dependent electrical characterization from 298 to 448 K reveals key insights. The forward current and turn-on voltage decrease linearly with increasing temperature, with a zero-temperature coefficient (ZTC) bias point observed at approximately 2.3 V. The reverse leakage current follows a thermally activated mechanism, as evidenced by a linear relationship between its natural logarithm and the reciprocal of absolute temperature behavior characteristic of a conventional p-n junction. These results underscore the broad prospects of Ga2O3 HJDs for next-generation high-voltage and high-power electronic applications.

This study investigates firstly the leakage-temperature correlation degradation mechanism of highly doped epitaxial β-Ga2O3 Schottky Barrier Diode (SBD) after 5 MeV proton irradiation. Experimental results show that post-irradiation, the carrier concentration decreases by 52.1% from 1.4×1016 cm-3 to 0.68×1016 cm-3, the Schottky barrier height rises from 0.81 eV to 0.93 eV, the ideality factor increases from 1.076 to 1.601, the specific on-resistance increases by over 17 mΩ • cm2, and the reverse leakage current increases by two orders of magnitude while reducing temperature sensitivity. On the other hand, pre-irradiation reverse leakage of the device—measured at 300-350K with reverse bias from -20 V to -200 V—is dominated by Poole-Frenkel Emission (PFE) with a deep trap state ΦT = 0.49 eV. For post-irradiation device, Trap-Assisted Tunneling (TAT) becomes dominant instead of PFE. TAT related to 0.22 eV and 0.43 eV two shallow trap states prevail two regions respectively at 300-350K from -130V to -200V, and at 300-330 K from -80V to -130V. PFE with the 0.52 eV trap state merely remains in a narrowed region spanning temperatures from 330K to 350K from -60 V to -130 V. This transition of mechanism is attributed to the synergistic effect of irradiation-induced shallow trap states with ΦT values of 0.22 eV and 0.43 eV coupling with anode-edge surface electric field concentration, which differs from the PFE-dominated failure in our low-doped β-Ga2O3 SBD. Thus, irradiation-introduced shallow trap states are the primary cause of reverse characteristic degradation and reduced temperature sensitivity in highly doped epitaxial β-Ga2O3 SBDs.

This work demonstrates the heteroepitaxial growth of single-phase beta-(AlxGa1-x)2O3 on (010) beta-Ga2O3 substrates via metalorganic chemical vapor deposition, achieving an aluminum composition of up to 22.6% with no phase segregation characterized by x-ray diffractometer. The surface morphology of epitaxial layer becomes rougher initially and then smoother with the increase of Al composition, suggesting that the rising Al composition leads to changes in the epitaxial growth mode. The fabricated MOSFETs based on beta-(Al0.09Ga0.91)2O3 epitaxial film achieve an ultra-high breakdown voltage over 3000 V and a high average breakdown field of 2.3 MV cm-1. This work underscores the potential of beta-(AlxGa1-x)2O3 heteroepitaxy technique and showcases its suitability for high-voltage power device applications.

In this study, impact of 5 MeV proton irradiation with radiation fluence of 1013 cm-2 on /3-Ga2O3 power diode is investigated by a /3-Ga2O3 Schottky barrier diode (SBD). Via temperature-dependent measurements, carrier removal rate RC is determined to be 7.26 x 102 cm-1 at 300 K. Meanwhile, the threshold voltage (Von) and ideality factor (n) almost remain stable after proton irradiation. A close-to-unity n was observed for a wide temperature range indicating near-ideal Schottky characteristics. Dynamic degradation was observed at 300K, but was greatly suppressed at a low temperature of 100K. Meanwhile, two more bulk traps are discovered in proton irradiated /3-Ga2O3 SBD by deep-level transient spectroscopy (DLTS). The larger corrected trap concentration (NTa) in proton irradiated /3-Ga2O3 SBD was regarded as the reason behind slightly worsened dynamic onresistance instability at 300 K. Furthermore, lower low frequency noise is revealed for proton irradiated device at room temperature and cryogenic temperature. The study demonstrates the competitive irradiation hardness of /3-Ga2O3 power diodes and paves a solid path for the deployment of /3-Ga2O3 in space.

This study investigates single-event burnout (SEB) effects in beta-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/(mgcm(2)), 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.

This paper investigates the single-event burnout (SEB) effect of β-Ga2O3 Schottky barrier diode (SBD) under atmospheric neutron irradiation, including the degradation modes and physical mechanisms. The experimental results indicate that the reverse bias voltage (UR) is a critical factor influencing SEB failure of β-Ga2O3 SBD devices. When UR reaches 600 V, SEB failure occurs, characterized as a sudden loss of voltage-blocking capability during atmospheric neutron irradiation. The Emission Microscope and Scanning Electron Microscopy analysis reveal that SEB events occur at the edge of the Schottky junction, with the damaged area forming an approximately elliptical molten “void.” Geant 4 and TCAD simulation results show that the incidence of secondary ions, such as Cr, causes a rise in the lattice temperature inside the device, with the maximum lattice temperature increasing as UR increases. When UR is sufficiently high, the local lattice temperature reaches the melting point of the Ga2O3 material, ultimately leading to SEB failure. This study provides valuable theoretical support for Ga2O3-based power devices in aerospace applications.

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 degrees C, the Schottky barrier height (Phi(B)) decreases from 1.09 to 1.03 eV, the ideality factor (n) decreases from 1.14 to 1.07, and the forward current density (J(F)) 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.

In this letter, (3-(AlxGa1-x)2O3 MOSFET with high breakdown voltage are demonstrated. A 150-nm (3-(Al0.14Ga0.86)2O3 epitaxial layer and a 30-nm Ga2O3 buffer were grown on Fe-doped semi-insulating (3-Ga2O3 substrate by metal-organic chemical vapor deposition. The epitaxial thin film exhibits relatively high crystalline quality, with a FWHM of 54 arcsec in the XRD rocking curve and a surface roughness of 2.3 nm. A T-shaped gate and source-field-plated are fabricated to mitigate electric field crowding. The (3-(Al0.14Ga0.86)2O3 MOSFET with source-drain length of 84 mu m demonstrates breakdown voltage of 7.2 kV, combined with the specific on-resistance of 3534 mS2 cm2, corresponding to power figures of merit of 14.7 MW/cm2. The results highlight the potential of (3-(AlxGa1-x)2O3 for high-voltage power electronics.

In this work, a superior-performance beta-Ga2O3 vertical Schottky barrier diode (SBD) with high breakdown voltage, low thermal resistance, low ON-resistance, high surge current, and high Baliga's figure of merit (FOM) is achieved by a composite terminal structure of mesa and dual field plate, combined with substrate thinning process. Grinding and polishing are utilized to eliminate the subsurface damage layer, thereby achieving a low ohmic resistance. Benefitting from the thinned substrate with a thickness of 85 mu m, the ON-resistance of device with 2 x 2 mm(2) anode area decreases from 174 to 112 m Omega. As a result, the corresponding forward current increases from 6.04 to 10.1 A at a bias of 2 V, and the surge current increases from 20 to 29 A. More importantly, the thermal resistance of the packaged device significantly reduces from 6.45 to 2.21 K/W, which is comparable to those of commercial SiC SBDs. Besides, a record Baliga's FOM of 342 MW/cm(2) with a breakdown voltage of over 1200 V is reached among reported beta-Ga2O3 SBDs with large anode area (>= 1.5 x 1.5 mm(2)). The results show the broad prospects of Ga2O3 SBD in high-voltage and high-power electronic devices.

The effects of 5 MeV proton irradiation on the electrical performance of beta-Ga2O3 Schottky barrier diodes (SBDs) are studied in this article to demonstrate the degradation mechanism and behavior related to defects and energy band. After proton irradiation with a fluence of 1 x 10(13) n/cm(2), the forward current density of beta-Ga2O3 SBD decreases, the barrier height rises by 0.2 eV, and the ideality factor degenerates from 1.056 to 1.092. The carrier concentration in the epilayer (from 1.05 x 10(16) to 0.3 x 10(16) cm(-3)), obtained from C-V characteristics, notably reduces due to trap states in the drift layer, leading to a higher barrier height. On the other hand, the Poole-Frenkel emission (PFE) mechanism is found to cause the reverse leakage of beta-Ga2O3 SBD after proton irradiation, utilizing temperature-dependent current-voltage I-V measurements. The deep-level transient spectroscopy (DLTS) measurements further reveal that E-c-0.82 eV (shifted to E-c-0.81 eV) originates from preexisting defects, while E-c-0.72 eV and E-c-1.04 eV are newly introduced by the proton irradiation. The relatively shallow trap states E-c-0.72 eV with a large capture cross section (2.25 x 10(-12) cm(-2)) contribute to PFE and dominate the trap-assisted leakage. Finally, the lower trap activation energy (from 0.82 to 0.72 eV) and higher Schottky barrier height (from 0.90 to 1.18 eV) both result in the degradation of both forward conduction and reverse leakage in beta-Ga2O3 SBDs.

In this letter, by implementing thermal oxidation (TO) technology, vertical Ga2O3 Schottky barrier diodes were directly fabricated on a heavily doped single-crystal (001) β-Ga2O3 substrate without epitaxial growth. The electron concentration in near-surface region of the Ga2O3 substrate was greatly reduced by introducing high-temperature TO processing. X-ray photoelectron spectroscopy (XPS) and photoluminescence (PL) results indicated that the oxygen vacancy (VO) content in the near-surface region was significantly decreased, while a 500–700 nm acceptor-like defect energy level combining multiple gallium vacancy (VGa) generated, and compensated for, the free carriers after annealing in an oxygen-rich atmosphere at high temperature. The annealing temperature and time were analyzed and optimized. Finally, vertical β-Ga2O3 SBDs with a breakdown voltage (Vbr) of 460 V, specific on-resistance (Ron,sp) of 10.5 mΩ·cm2 and a power figure-of-merit (PFOM) of 20.2 MW/cm2, were demonstrated when the annealing temperature and time were 900 °C and 2 h. These results indicate that vertical β-Ga2O3 SBDs can be directly fabricated on a single-crystal substrate without epitaxial growth, providing a new method of reducing the cost of such devices.

This article focuses on investigating the totalionizing dose (TID) effects of beta-Ga2O3-based Schottky barrier diodes (SBDs). The TID degradation behavior and mechanisms are evaluated by varying irradiation bias conditions, conducted through dc, capacitance-voltage (C-V),and low-frequency noise (LFN) measurements. At a dose of 1 Mrad(Si), the irradiated devices demonstrate a notice-able increase in both forward and reverse currents. This increase is primarily attributed to the rise in defect con-centration caused by ionizing damage resulting from TID effects. The TID degradation of beta-Ga2O3 SBD is significantly influenced by bias conditions, with devices under high electric fields experiencing more severe degradation. Specifically, a high reverse electric field during radiation leads to a notable increase in interface defects of beta-Ga(2)O(3 )SBDs, this result was validated through TCAD simulation. The reverse bias voltage exacerbates TID effects and reduces the radiation tolerance of beta-Ga2O3 SBD devices.

This study investigates the displacement damage in beta-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 paper focuses on the impacts of 5 MeV proton irradiation on the electrical performance of beta-Ga2O3 Schottky barrier diodes (SBDs), aiming to elucidate the degradation mechanisms and behaviors associated with defects and the energy band. Several changes occur when beta-Ga2O3 SBDs are irradiated with a fluence of 1x10(13) n/cm(2). The forward current density of the beta-Ga2O3 SBDs decreases, the barrier height increases by 0.2 eV, and the ideality factor deteriorates from 1.056 to 1.092. Based on the CV characteristics, the carrier concentration in the epilayer significantly declines from 1.05x10(16) cm(-3) to 0.32x10(16) cm(-3). This reduction is attributed to the trap states in the drift layer, leading to an increase in the barrier height. Moreover, temperature-dependent IV measurements show that the Poole-Frenkel emission (PFE) mechanism is responsible for the reverse leakage of beta-Ga2O3 SBDs after proton irradiation. DLTS measurements further reveal that the trap state E-c-0.82 eV splits into E-c-0.72 eV, E-c-0.81 eV, and Ec-1.04 eV following proton irradiation. The relatively shallow trap state E-c-0.72 eV, featuring a large capture cross-section of 2.25x10(-12) cm(-2), contributes to the PFE and dominates the trap-assisted leakage. Ultimately, the decrease in trap activation energy (from 0.82 eV to 0.72 eV) and the increase in Schottky barrier height (from 0.90 eV to 1.18 eV) jointly lead to the degradation of both forward conduction and reverse leakage in beta-Ga2O3 SBDs.