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In this paper, the p-GaN gate AlGaN/GaN high electron mobility transistors (HEMTs) with varying combinations of gate metal work function and gate geometry are fabricated and investigate the influence of gate leakage current (IGS) on the threshold voltage (VTH) and subthreshold swing (SS). The unique dependence of VTH and SS on gate geometry for different metals is observed, which is different from traditional field-effect transistors. A novel hybrid physics model, consisting of the traditional capacitance divider model and hole injection model, is proposed to explain this phenomenon, and the results exhibit an excellent agreement with the experimental data. The holes traverse the gate/p-GaN Schottky barrier by thermal emission or tunneling and inject into the p-GaN layer, generating the IGS. Expanding upon the traditional capacitance divider model, a portion of the injected holes accumulate at the p-GaN/AlGaN interface and induce the corresponding electrons at the AlGaN/GaN heterojunction, which promotes channel conduction. Hence, the transfer curves display the correlation between IGS and VTH as well as SS. The results show that high IGS can alleviate the instability of VTH caused by the lithographic overlay error, and simultaneously optimize SS. This work offers a novel perspective for examining the turn-on mechanism of p-GaN HEMTs, thereby contributing to device design. [ABSTRACT FROM AUTHOR]

The impact of Fröhlich scattering on β‐Ga2O3 Schottky barrier diodes (SBDs) electron mobility, particularly at high temperatures, is investigated. This scattering is crucial due to electron–polar optical phonon interactions. Temperature‐dependent I–V characteristics of a β‐Ga2O3 SBD from 300 to 473 K showed significant current reduction due to electron–polar optical phonon scattering, supported by correlation with mobility profiles. Additionally, in situ temperature‐dependent XPS analysis revealed a notable positive shift in core‐level binding energy, attributed to heightened electron–phonon interactions. This study provides crucial insights into carrier transport mechanisms, essential for power device design and operation. [ABSTRACT FROM AUTHOR]

The impact of heavy ion irradiation on the β-Ga2O3 p-n diode and its physical mechanism have been studied in this Letter. After the irradiation fluence of 1 × 108 cm−2, it is observed that the electrical performance of the device is significantly degraded. The forward current density (JF) is reduced by 49.4%, the reverse current density (JR) is increased by more than two orders of magnitude, and the breakdown voltage (VBR) is decreased by 30%. Based on the results of the deep-level transient spectroscopy measurement, it is concluded that acceptor-like traps generated with an energy level of EC-0.75 eV in the β-Ga2O3 drift layer dominate the JF degradation of the device, which are most likely related to Ga vacancies. These acceptor-like traps result in the reduction of change carrier concentration, which in turn leads to a decrease in JF. In addition, according to the conductive atomic force microscope measurements and theoretical calculation, it is clearly observed that the latent tracks induced by heavy ion irradiation can act as leakage paths, leading to a significant degradation of JR and VBR. [ABSTRACT FROM AUTHOR]

A 47–52‐GHz power amplifier (PA) Microwave Monolithic Integrated Circuit (MMIC) with silicon carbon (SiC)‐based gallium nitride (GaN) was reported in this work. The circuit solution gives particular consideration to the loss of matching the output matching network. In pulse conditions, the PA can reach a maximum saturated output power of 43 dBm (20 W) with typical gain values of 18 dB and power‐added efficiency of 21%. The output power at −1 dB gain compression (P1dB ${P}_{1dB}$) is 40.2 dBm, and the power density is up to 3.36 W/mm in the active periphery under the drain voltage of 24 V. The chip is compact with an area of 5.6 × 3.7 mm2. This PA achieves higher output power in comparison to the reported PA MMIC. [ABSTRACT FROM AUTHOR]

GaN HEMT devices are sensitive to the single event effect (SEE) caused by heavy ions, and their reliability affects the safe use of space equipment. In this work, a Ge ion (LET = 37 MeV·cm2/mg) and Bi ion (LET = 98 MeV·cm2/mg) were used to irradiate Cascode GaN power devices by heavy ion accelerator experimental device. The differences of SEE under three conditions: pre-applied electrical stress, different LET values, and gate voltages are studied, and the related damage mechanism is discussed. The experimental results show that the pre-application of electrical stress before radiation leads to an electron de-trapping effect, generating defects within the GaN device. These defects will assist in charge collection so that the drain leakage current of the device will be enhanced. The higher the LET value, the more electron–hole pairs are ionized. Therefore, the charge collected by the drain increases, and the burn-out voltage advances. In the off state, the more negative the gate voltage, the higher the drain voltage of the GaN HEMT device, and the more serious the back-channel effect. This study provides an important theoretical basis for the reliability of GaN power devices in radiation environments. [ABSTRACT FROM AUTHOR]

Herein, a high‐quality In0.1Al0.5Ga0.4N/GaN three‐channel (TC) heterostructure and the high‐electron‐mobility transistor (HEMT) based on it are proposed and investigated. The quaternary nitrides offer additional flexibility in adjusting the lattice constant and bandgap, enabling the achievement of a nearly strain‐free high‐Al‐content barrier. By stacking three In0.1Al0.5Ga0.4N/GaN heterostructures, a high 2D electron gas density of 2.59 × 1013 cm−2 and a high electron mobility of 1707 cm2 V−1 s−1 are achieved. As compared with the AlGaN/GaN TC heterostructure, the In0.1Al0.5Ga0.4N/GaN TC heterostructure reduces the sheet resistance by 39%, resulting in a 40 % reduction in the on‐resistance of the TC HEMT. Additionally, the inverse piezoelectric effect of the In0.1Al0.5Ga0.4N/GaN TC‐HEMT is investigated by negative‐gate voltage bias step‐stress experiments. During the stress experiments, no irreversible degradation is observed in the In0.1Al0.5Ga0.4N/GaN TC‐HEMT, while the AlGaN/GaN TC‐HEMT exhibits a significant deterioration beyond the critical voltage. The reliability related to the inverse piezoelectric effect of the devices can be further improved due to the lower stress in the lattice‐matched quaternary barrier. [ABSTRACT FROM AUTHOR]

In this paper, a beta-phase gallium oxide (β -Ga2O3) vertical FinFET with diamond-gate has been studied by Silvaco-ATLAS simulation. The diamond-gate structure achieves adjustable pin (p-insulator-n) junction owing to the diamond-SiO2-Ga2O3 heterostructure. This design also enhances heat dissipation by virtue of the high thermal conductivity of the diamond. Compared to conventional FinFETs, the diamond-gate FinFET (DG-FinFET) reduces the static operating temperature rise by around 17.30%. Additionally, due to its greater heat dissipation capacity, DG-FinFETs provide a 5.84% increase in current density at 1 kA cm−2 current density level. The structural changes in the diamond-gate also result in a significant reduction in the gate-source capacitance (C GS). At 1 MHz operating frequency and the same gate voltage, DG-FinFETs have 69.29% less gate-source charge (Q GS), 70.80% less charge/discharge delay time, 73.70% less switching loss, and 57.15% less conduction loss. Overall, the simulation and analysis presented in this work indicate a promising advancement of the DG-FinFET structure in high-power and rapid switching applications. [ABSTRACT FROM AUTHOR]

Herein, a metal/insulator/p‐GaN gate HEMT (MIP‐HEMT) with Si3N4 gate dielectric layer is fabricated. Compared to the conventional p‐GaN HEMT, the MIP‐HEMT has a higher threshold voltage (Vth) of 4.8 V and better gate leakage suppression. The mechanism of threshold voltage increase in MIP‐HEMT is elucidated through an analysis of the electric field distribution in the gate region and the proposed gate capacitance model. Furthermore, MIP‐HEMTs with gate dielectric layers of varying dielectric constants and thicknesses are designed and simulated. The obtained results lead to the derivation of an empirical formula for the threshold voltage of the MIP‐HEMT under ideal dielectric/p‐GaN interface conditions, in relation to the dielectric constant and thickness of the gate dielectric layer. Additionally, simulations are conducted on the MIP‐HEMT incorporating fixed charges at the dielectric/p‐GaN interface, and the impact of interface charges is investigated. This refinement enables a more accurate prediction of the MIP‐HEMT's threshold voltage. Conclusively, MIP‐HEMTs can effectively modulate the threshold voltage by manipulating the parameters of the gate dielectric layer, thereby extending the threshold voltage range of conventional enhancement‐mode devices. [ABSTRACT FROM AUTHOR]

P‐type NiOx is employed for the fabrication of NiO/Ga2O3 p–n diode. Addressing the challenge of low hole mobility in NiOx, an extensive investigation into the impact of oxygen stoichiometry engineering in NiOx is conducted. The meticulous optimization of the O2/Ar ratio to 30% during the sputtering process results in significant improvements, notably achieving enhanced hole mobility of 1.61 cm2 V−1 s. It leads to a low specific on‐resistance of 2.79 mΩ cm2 and a high rectification ratio of ≈1011, underscoring the efficacy of recombination transport mechanism driven by enhanced hole mobility. Detailed band alignment analysis between NiOx and Ga2O3 reveals a small band offset, with a valence band offset of 2.47 eV and a conduction band offset of 1.70 eV. It suggests a tailored modification of band alignment through the engineering the oxygen stoichiometry in NiOx, facilitating enhanced recombination conduction. The device exhibits a superior breakdown voltage (Vb) of 2780 V and a notable Baliga's figure of merit (BFOM) of 2.77 GW cm−2, surpassing the SiC unipolar figure of merit. The insights gained from this work are expected to inform future designs and optimizations of high‐performance Ga2O3 electronic devices. [ABSTRACT FROM AUTHOR]

Degradation and trap evolution in NiO/β-Ga2O3 heterojunction pn diodes under on-state electrical stress were investigated in this work using deep-level transient spectroscopy measurements and density functional theory (DFT) calculations. The decrease in turn-on voltage and forward current appears to correlate with an increase in the concentration of the compensating acceptor-like traps. From the energy level of EV + 1.3 eV, the corresponding acceptor-like traps can be attributed to the Ga vacancy complex with hydrogen (VGa-H). Interestingly, accompanied by the increase in VGa-H concentration, the self-trapped holes (STH) originally passivated by H may gradually recover. DFT calculations show a monotonous decrease in energy, suggesting the spontaneous diffusion of hydrogen from STH passivated sites to the adjacent VGa, which are generated under stress. This phenomenon leads to the recovery of STH and the generation of VGa-H. This investigation offers new insights into the degradation mechanisms of β-Ga2O3-based devices under electrical stress. [ABSTRACT FROM AUTHOR]