In this work, a δ-doped p-GaN/u-GaN/AlGaN multi-channel heterostructure is proposed and fabricated by metal-organic chemical vapor deposition (MOCVD). Hall measurement results indicate that the optimized multi-channel structure achieves a record-low sheet resistance of 7529 Ω/□ by MOCVD. The AlGaN/GaN/AlGaN sandwich structure strengthens the quantum confinement for holes and leads to a high polarization-induced hole density of 8.80 × 1013 cm−2. By spatially segregating charge carriers across multiple channels, the multi-channel architecture mitigates inter-carrier scattering and achieves a carrier mobility of 9.42 cm2/V·s. Besides, employing an InGaN layer as the ohmic contact layer significantly reduces the sheet resistance. This achievement provides an important material foundation for the development of high-performance GaN-based p-channel field-effect transistors.

In this work, a novel Schottky-gated p-channel GaN field-effect transistor (PFET) with a tunable n-GaN sub-gate layer is investigated. Terminal-current analysis under the actual drain-bias condition shows that the gate-current contribution remains limited within the defined effective operating range of VGS ≥ −3.2 V, whereas gate-related current becomes significant at more negative gate biases. Carrier-resolved and spatial current analyses further confirm that, within this operating range, the drain current is predominantly carried by holes through an interfacial hole channel near the p-GaN/AlGaN heterointerface. Benefiting from the intentionally introduced p–n junction beneath the groove gate, the built-in electric field effectively depletes the p-GaN channel, enabling a robust transition from depletion-mode to enhancement-mode (E-mode) operation. By precisely scaling the n-GaN layer thickness (0–5 nm) and donor concentration (3.0 × 1017 cm−3 to 3.0 × 1019 cm−3), the buried p-n junction modulates the depletion condition and hole distribution beneath the gate. The optimized device exhibits a significantly improved subthreshold swing (SS) of 348 mV/dec, while maintaining a stable ION/IOFF ratio on the order of 102. This tunable sub-gate architecture provides a highly flexible platform for optimizing E-mode GaN PFETs, showing great promise for high-performance complementary logic applications.

In this work, a temperature sensor based on multiheterostructure GaN p-i-n diode with a turn-on voltage (V (on) ) of 4.25 V and a high I (on) /I (off )ratio over 1 & times;10(7) is demonstrated. The fabricated GaN p-i-n diode shows a high-temperature sensitivity of 3.63 mV/K at a low forward current of 1 & times;10(-6) A. The wave functions of electrons and holes are modulated by the inserted InGaN quantum well, and a peak recombination rate of 1.93 & times;10(24) cm( -3)& sdot;s(-1 )with a forward current of 1 & times;10(-6) A is obtained by TCAD. The zero-temperature coefficient (ZTC) point is 5.1 V measured at various temperatures. Meanwhile, the reverse I - V characteristics also present a temperature-dependent behavior with a temperature sensitivity of 8.61 mA/K at a reverse biased voltage of -5 V.

Low-dislocation GaN epitaxy on flat sapphire remains challenging when sputtered AlN is used as the nucleation layer because the near-surface state of sputtered AlN can limit subsequent GaN nucleation and coalescence. Here, we introduce Al-ion pretreatment as a pre-growth interface-engineering strategy for sputtered AlN on flat sapphire. With an optimized implantation dose, the GaN mosaic structure is markedly improved. The total threading dislocation density is reduced by 50.5% relative to the conventional substrate. X-ray photoelectron spectroscopy indicates implantation-induced reorganization of the oxygen-related near-surface bonding environment, resulting in a more uniform AlN-like surface for subsequent GaN. Ultraviolet light-emitting diodes grown on the optimized templates also exhibit improved electrical and optical performance. These results demonstrate Al-ion pretreatment as a practical route for low-dislocation GaN epitaxy on sputtered-AlN/flat-sapphire templates.

In this work, N-ion implantation pretreatment was introduced into sapphire substrates with sputtered AlN to improve the crystal quality and conductivity of GaN p-channel heterostructures. The effects of different N-ion implantation doses on the material quality and electrical properties of GaN p-channel heterostructures were investigated. Compared with the conventional substrate, the ion-implanted substrates reduced the threading dislocation density and improved the surface morphology. At an implantation dose of 1 × 1012 cm-2, the p-channel heterostructure shows a 26.7% reduction in dislocation density. The sheet hole density increases by 20.0%, while the sheet resistance decreases by 10.9%. These results indicate that N-ion implantation pretreatment is an effective route to improve the conductivity of GaN p-channel heterostructures for future p-FET applications.

In this work, AlGaN/GaN reverse conduction HEMTs (RC-HEMTs) integrated with anti-parallel Schottky barrier diodes (SBDs) are demonstrated. Benefiting from the idealized Schottky interface of AlGaN/GaN SBDs with recessed anode, which enables direct contact between GaN channel and anode metal, low reverse turn-on voltage (VR-T) of -0.75 V and high I-ON/I-OFF ratio of 8.5 & times; 10(7) are obtained. Based on the randomly measured 100 RC-HEMTs with L-GD of 15 mu m, ultra-high VR-T uniformity with standard deviation of 18 mV and forward on-resistance (R-ON) uniformity with standard deviation of 0.3 Omega mm are calculated, respectively. Furthermore, the breakdown voltage of the fabricated AlGaN/GaN RC-HEMT with a 30-mu m L-GD can reach 2.7 kV, which shows great promise for medium-voltage power applications.

In this letter,we demonstrate the effect of γ irradiation on the lateral AlGaN/GaN Schottky barrier diodes(SBDs)with self-terminated recessed anode structure and low work-function metal tungsten(W)as anode.For a comprehensive evaluation of the radiation-resistance performance of the device,the total dose of γ irradiation is up to 100 kGy with irradiation time of 20 h.Attributed to the barrier lowering effect of the W/GaN interface induced by γ irradiation observed in the experiment,the extracted turn-on voltage(VON)defined at anode forward current of 1 mA decreases from 0.47 to 0.43 V.Meanwhile,benefit-ing from the reinforced Schottky interface treated by post-anode-annealing,a high breakdown voltage(BV)of 1.75 kV is obtained for the γ-irradiated AlGaN/GaN SBD,which shows the promising application for the deep-space radiation environ-ment and promotes the development of radiation-resistance research for GaN SBDs.

In this work, current-collapse suppressed highperformance AlGaN/GaN Schottky barrier diodes (SBDs) with excellent reverse blocking characteristics are demonstrated. Benefiting from the modulated electric field via an optimized $6-\mu \mathrm{m}$ PN junction termination and the in-situ NH3 plasma treated GaN passivation layer at the active region, the fabricated AlGaN/GaN SBD with $100-\mu \mathrm{m}$ anode-to-cathode distance ($L_{\text{AC}}$) achieves a high breakdown voltage over -10 kV and a high Baliga's figure-of-merit (FOM) over 2.1 $\text{GW} / \text{cm}^{2}$. Meanwhile, compared to the static characteristics, the degradation of dynamic differential on-resistance (Ron, dyn) and dynamic turn-on voltage ($V_{O N, d y n}$) are extracted to be 19.1 % and 3.7 %, respectively, after a 1000 -s-long bias test at -3 kV. The impressively high breakdown and dynamic performance show great potential for next-generation medium-and-high voltage powerelectronic applications.

In this work, a high-performance AlGaN-channel Schottky barrier diode with high breakdown voltage of 2.23 kV defined at anode leakage current of 1 μA and high power figure-of-merit of 614 MW/cm2 is demonstrated. Anode voltage (VA) with a clear linear relationship as a function of temperature from 300 to 525 K shows great potential for temperature sensors, and maximum temperature sensitivity of 2.0 mV/K at anode current density (IA) of 6.28 × 10−8 A is obtained, satisfying the low power consumption requirement. Meanwhile, the corresponding temperature sensitivity of ln(–I) vs temperature at a fixed VA of –15 V is 5.0 mA/K, and the suppressed temperature sensitivity at reverse bias is attributed to the energy-band modulated Schottky barrier height of AlGaN-channel M/S interface, which is vital for high-temperature and high-power applications.

In this work, the electrical properties of the Ga2O3 Schottky barrier diodes (SBDs) using W/Au as the Schottky metal were investigated. Due to the 450 °C post-anode annealing (PAA), the reduced oxygen vacancy defects on the β-Ga2O3 surface resulted in the improvement in the forward characteristics of the W/Au Ga2O3 Schottky diode, and the breakdown voltage was significantly enhanced, increasing by 56.25% from 400 V to 625 V after PAA treatment. Additionally, the temperature dependence of barrier heights and ideality factors was analyzed using the thermionic emission (TE) model combined with a Gaussian distribution of barrier heights. Post-annealing reduced the apparent barrier height standard deviation from 112 meV to 92 meV, indicating a decrease in barrier height fluctuations. And the modified Richardson constants calculated for the as-deposited and annealed samples were in close agreement with the theoretical value, demonstrating that the barrier inhomogeneity of the W/Au Ga2O3 SBDs can be accurately explained using the TE model with a Gaussian distribution of barrier heights.

In this work, current-collapse suppressed high-performance AlGaN/GaN Schottky barrier diodes (SBDs) with excellent reverse blocking characteristics are demonstrated. Benefiting from the modulated electric field via an optimized 6-pm PN junction termination and the in-situ NH3 plasma treated GaN passivation layer at the active region, the fabricated A1GaN/GaN SBD with 100-pm anode-to-cathode distance (L-Ac) achieves a high breakdown voltage over 10 kV and a high Baliga's figure-of-merit (FOM) over 2.1 GW/cm(2). Meanwhile, compared to the static characteristics, the degradation of dynamic differential on-resistance (R-ON,R-dyn) and dynamic turn-on voltage (V-ON,V-dyn) are extracted to be 19.1% and 3.7%, respectively, after a 1000-s-long bias test at 3 kV. The impressively high breakdown and dynamic performance show great potential for next-generation medium-and-high voltage powerelectronic applications.

In this work, electric field-modulated AlGaN/GaN Schottky barrier diodes (SBDs) with an AlN back barrier layer and a thin GaN channel layer are demonstrated. Benefiting from the built-in electric field (E-B) induced via the positively polarized charge at the AlGaN/GaN interface and the negatively polarized charge at the GaN/AlN interface, the composite electric field in the GaN channel is effectively suppressed, when the diodes are reverse-biased. Compared to traditional GaN buffer SBDs, the breakdown voltage of AlGaN/GaN SBDs with AlN back barrier layer increases from -585 to -1122 V while the power figure-of-merit increases from 215 to 777 MW/cm(2).

In this work, we report a p-GaN/u-GaN/AlGaN multi-channel structure using δ-doping. The multi-channel structure exhibits a low sheet resistance of 12.9 kΩ/sq. The AlGaN/GaN/AlGaN sandwich structure results in a significant reduction in channel width and a substantial increase in restricted ability for holes. The multi-channel structure has markedly enhanced sheet hole density in comparison to the conventional single-channel structure. Meanwhile, the carriers are distributed in different channels, thereby diminishing the inter-carrier scattering effect. The hole mobility of the multi-channel structure remains largely unaffected by the increased sheet hole density. Due to the excellent conductivity, the ohmic contact resistance of the multi-channel structure is as low as 15.9 Ω mm. Moreover, a p-channel FinFET device was fabricated based on the multi-channel structure. The device exhibits a remarkable high saturation current density of 112 mA/mm, which indicates that the multi-channel structure has potential for high-performance GaN p-channel field effect transistors.

In this letter, a Schottky-gated p-GaN/u-GaN/AlGaN p-channel metal-semiconductor field-effect transistor on a SiC substrate with high irradiation tolerance is demonstrated, and the irradiation-induced degradation mechanism is also revealed. The devices exhibit a slight degradation in the saturation drain current and a negative shift of threshold voltage. Meanwhile, the fabricated devices exhibit outstanding stability, even after ten-consecutive dual-sweep, dual-sweep with various scan ranges, and long-time stress measurements. However, an increase in hysteresis and the occurrence of a knee point in dual-sweep transfer characteristics have been observed. The trap distributions under the gate after irradiation, extracted using the frequency-dependent conductance method, show that the trap state density increases from 5.68-9.05 x 10(12) to 0.72-2.35 x 10(13) cm(-2) eV(-1), accompanied by a shift in trap energy from 0.32-0.35 to 0.33-0.43 eV. The introduction of deep-level and high-density traps captures a large number of holes, leading to current degradation, increased hysteresis, and knee point.

In this study, a high-performance p-channel InGaN metal-semiconductor field-effect transistor (MES-FET) is demonstrated, featuring an energy-band modulated p-GaN/InGaN/AlN composite-channel and a nano-scaled tungsten (W) Schottky gate. Taking advantage of the quantum well-like InGaN channel for enhanced hole confinement, combined with a nano-scaled gate design and an ideal Schottky gate interface, the device achieves a remarkably low off-state leakage current of 0.97 pA/mm, a record I-ON/I-OFF ratio of 1.5x10(9), and a steep subthreshold swing of 77 mV/dec. The fabricated p-channel InGaN MESFET, featuring a reduced gate-to-drain distance of 0.83 mu m, demonstrates a high breakdown voltage of-105 V and a negative threshold voltage of-0.85 V. Meanwhile, owing to the idealized W Schottky gate contacting to p-GaN, an ultra-low hysteresis voltage of 0.03 V is obtained, when subjected to multiple dual sweeps across diverse gate voltage ranges and prolonged stress time.

In this work, high-performance double-channel AlGaN/GaN Schottky barrier diodes with AlN super back barrier are demonstrated, and the corresponding current transport mechanisms at various anode bias voltages are studied. Benefiting from the electric field-modulated GaN double channel via polarized charge, high output current of 339 mA/mm and high breakdown voltage of 2.18 kV are obtained. The initial leakage current is dominated by thermionic emission, when the anode is biased at a small voltage. With the increase in anode voltage, electrons in the GaN channel are partly depleted, and two-dimensional variable-range hopping, through high-density trap states in the GaN-based material, dominates the total leakage current. When the anode reverse bias is large enough to fully deplete electrons in channel, the temperature-dependent leakage current shows little dependence on the applied anode voltage, and the trap-assisted tunneling model satisfies.

In this letter, a normally-off p-channel GaN metal-semiconductor field-effect transistor (MESFET) on SiC substrate with high I-ON/I-OFF ratio and barrier-freed ohmic contact was first demonstrated. Compared to the polarization-enhanced p-GaN/AlN/AlGaN on Si substrate, the same designed epitaxial wafer on SiC substrate showed a decreased surface potential from 11 to -368 mV as well as 1.9 times lower contact resistance (R-C), modulated by dislocation-related potential. Meanwhile, high I-ON/I-OFF ratio of 3.3 x 10(7), ultralow hysteresis voltage of 0.05 V, and subthreshold swing (SS) of 83 mV/dec were obtained. The well-behaved characteristics of p-channel GaN MESFET on SiC substrate with negligible turn-on voltage and high I-ON/I-OFF ratio show great potential for low-voltage complementary metal-oxide-semiconductor (CMOS) applications.

GaN based Schottky barrier diode (SBD) possesses advantages including high power density, high conversion efficiency, and excellent switching characteristics. During heteroepitaxial growth of GaN, a high density of threading dislocations is inevitably introduced, which can degrade device reliability. This paper reports a low dislocation density N+/N- GaN quasi-vertical SBD fabricated on a freestanding GaN substrate. The characterization results of high-resolution X-ray diffraction and atomic force microscopy demonstrate that the high-quality epitaxial layer with a total dislocation density of 1.01 x 10(8) cm(-2) and a root mean square surface roughness of 0.149 nm is achieved on a freestanding GaN substrate. The device prepared based on a high-quality epitaxial layer exhibits an ultra-low leakage current density of 10(-5) A/cm(2) at a reverse voltage of -5 V, without employing any edge termination structures or field plates or plasma treatment. Compared with the devices prepared on sapphire substrates using identical processes, the device prepared in this work reduces the reverse leakage current by four orders of magnitude. The experimental results show that the quasi-vertical GaN based SBD fabricated on a freestanding GaN substrate significantly reduces reverse leakage current and substantially enhances the overall electrical performance of the device. By employing emission-microscope (EMMI), leakage current in quasi-vertical SBD is identified to be primarily localized at the anode edge, and the underlying leakage mechanism is elucidated. Finally, temperature-dependent measurements demonstrate that the device maintains a leakage current below 10(-3) A/cm(2) at 100 degrees C, confirming the potential of quasi-vertical SBD on freestanding GaN substrate for practical applications.

In this study, a high-performance p-channel InGaN metal-semiconductor field-effect transistor (MES-FET) is demonstrated, featuring an energy-band modulated p-GaN/InGaN/AlN composite-channel and a nano-scaled tungsten (W) Schottky gate. Taking advantage of the quantum well-like InGaN channel for enhanced hole confinement, combined with a nano-scaled gate design and an ideal Schottky gate interface, the device achieves a remarkably low off-state leakage current of 0.97 pA/mm, a record $I_{\text{ON}}/I_{\text{OFF}}$ ratio of $1.5\times 10^{9}$, and a steep subthreshold swing of 77 mV/dec. The fabricated p-channel InGaN MESFET, featuring a reduced gate-to-drain distance of $0.83\ \mu \mathrm{m}$, demonstrates a high breakdown voltage of −105 V and a negative threshold voltage of −0.85 V. Meanwhile, owing to the idealized W Schottky gate contacting to p-GaN, an ultra-low hysteresis voltage of 0.03 V is obtained, when subjected to multiple dual sweeps across diverse gate voltage ranges and prolonged stress time.