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Different Isolation Processes for Free-Standing GaN p-n Power Diode with Ultra-High Current Injection
摘要： In this article, we report on the fabrication and high performance of power p-n diodes grown on free-standing (FS) GaN substrate. The key technique to enhance the high breakdown voltage and suppress the surface leakage current is the isolation process. The mesa-structure diode is generally formed by utilizing the inductively coupled plasma reactive ion etching (ICP-RIE); however, it always induces high surface damages and thus causes a high leakage current. In this study, we propose a planar structure by employing the oxygen ion implantation to frame the isolation region. By following the crucial process, the fabricated mesa- and planar-type diodes exhibit the turn-on voltages of 3.5 and 3.7 V, specific on-resistance (RONA) of 0.42 and 0.46 mΩ-cm2, and breakdown voltage (VB) of 2640 and 2880 V, respectively. The corresponding Baliga’s figures of merit (BFOM, i.e., VB2/RONA) are 16.6 and 18 GW/cm2, respectively. The BFOM of 18 GW/cm2 is the highest reported value for FS-GaN diode. From the temperature dependent measurements, the planar-type diode also shows the better leakage current and thermal stability than the mesa-type diode.
关键词： leakage current,Baliga’s figure of merit,breakdown voltage,planar diode,implantation,GaN substrate
更新于2025-09-23 15:22:29
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High-voltage regrown nonpolar m-plane vertical p-n diodes: A step toward future selective-area-doped power switches
摘要： We report high-voltage regrown nonpolar m-plane p-n diodes on freestanding GaN substrates. Secondary-ion mass spectroscopy (SIMS) measurements indicate O and Si spikes at the regrowth interfaces with maximum concentration ~ 5×1017 cm-3, which is similar to previously published c-plane studies. A high blocking voltage of 540 V at ~ 1 mA/cm2 (corresponding to an electric field of E ~ 3.35 MV/cm), turn-on voltages between 2.9-3.1 V, specific on-resistance of 1.7 mΩ.cm2 at 300 A/cm2, and a minimum ideality factor of 1.7 were obtained for the regrown diodes. Our results suggest that Si, O and C interfacial impurity levels up to 2×1017 cm-3, 8×1017 cm-3, and 1×1019 cm-3, respectively, at the metallurgical junction of m-plane p-n diodes do not result in very early breakdown in the reverse bias, although the off-state leakage current in forward bias is affected. The impact of growth interruption/regrowth on diode performance is also investigated.
关键词： Selective-area doping,GaN,Specific on-resistance,Impurity incorporation,Avalanche breakdown,Leakage currents,Ideality factor,Nonpolar,SIMS,Vertical p-n diodes
更新于2025-09-23 15:22:29
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[IEEE 2018 5th NAFOSTED Conference on Information and Computer Science (NICS) - Ho Chi Minh, Vietnam (2018.11.23-2018.11.24)] 2018 5th NAFOSTED Conference on Information and Computer Science (NICS) - Joint Image Deblurring and Binarization for License Plate Images using Deep Generative Adversarial Networks
摘要： Image deblurring is a highly ill-posed inverse problem where it aims to estimate the sharp image from blurred image with or without the knowledge about the blurring process. Despite the success of model-based image deblurring methods where the deconvolution is a major step to recover the sharp image, its usage in practice is still limited, especially when many factors such as object motion, camera motion, non-uniform sensitivity of the imaging device contribute to imaging process. In automatic license plate recognition (ALPR) of moving vehicle, the blurred image severely reduces the accuracy of recognition. Meanwhile, though the binarized image of license plate has an important role in ALPR systems, its accuracy is largely affected by the blurred image. In this paper, we use a deep architecture based on Generative Adversarial Networks to jointly perform image deblurring and image binarization for license plate images. Our model directly maps from blurred image to binary image without going through the deblurring as in conventional method. The proposed method is benefited from the fact that the ground-truth, sharp license plates are difficult to acquire for moving object, while the accurate binary images can be manually derived from blurred ones.
关键词： Inverse Problems,License Plate Deblurring,Image Deblurring,Generative Adversarial Network (GAN)
更新于2025-09-23 15:22:29
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Comparative Analysis of Defects in Mg-Implanted and Mg-Doped GaN Layers on Freestanding GaN Substrates
摘要： Inefficient Mg-induced p-type doping has been remained a major obstacle in the development of GaN-based electronic devices for solid-state lighting and power applications. This study reports comparative structural analysis of defects in GaN layers on freestanding GaN substrates where Mg incorporation is carried out via two approaches: ion implantation and epitaxial doping. Scanning transmission electron microscopy revealed the existence of pyramidal and line defects only in Mg-implanted sample whereas Mg-doped sample did not show presence of these defects which suggests that nature of defects depends upon incorporation method. From secondary ion mass spectrometry, a direct correspondence is observed between Mg concentrations and location and type of these defects. Our investigations suggest that these pyramidal and line defects are Mg-rich species and their formation may lead to reduced free hole densities which is still a major concern for p-GaN-based material and devices. As freestanding GaN substrates offer a platform for realization of p-n junction-based vertical devices, comparative structural investigation of defects originated due to different Mg incorporation processes in GaN layers on such substrates is likely to give more insight towards understanding Mg self-compensation mechanisms and then optimizing Mg doping and/or implantation process for the advancement of GaN-based device technology.
关键词： Line defects,Pyramidal defects,SIMS,GaN,STEM
更新于2025-09-23 15:22:29
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[IEEE 2018 China International SAR Symposium (CISS) - Shanghai (2018.10.10-2018.10.12)] 2018 China International SAR Symposium (CISS) - Developemet of C-Band High Integration & High Efficiency Space-Borne T/R Module
摘要： As the hardcore of phased array antennas, the development of highly reliable T/R module for satellite SAR application becomes the research sticking point. Due to satellite In SAR application, the T/R module is required for high-efficiency, low-loss, low-mass, high amplitude and phase stability and high reliability. In this paper, a C-band Dual-channels T/R Module based on GaN high power MMIC and GaAs high-integrated multifunctional MMIC with multichip module (MCM) packing technics is introduced, which realizes the integration of microwave signal amplification, T/R control, digital amplitude and phase control, high voltage modulation. Compared with GaAs technics, the power amplifier based on GaN MMIC has higher output power and higher power added efficiency, accordingly decreases the total heat loss consumedly of SAR system. The T/R module channel provides over 41.5dBm output power, 29dB receive gain and 2.8dB noise figure, over 37% power added efficiency, weight only 35g, the size is 64mm×39.6mm×7mm, with high-efficiency and low-loss, miniaturization and low-mass, high reliability.
关键词： Space-borne,GaN,Multichip module(MCM),T/R module
更新于2025-09-23 15:22:29
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Study of Proton Irradiation Effects on p- and n-Type GaN Based-on Two-Terminal Resistance Dependence on 380keV Proton Fluence
摘要： 380 keV proton irradiation effects are investigated on p-GaN and n-GaN layers in GaN-based light emitting diode (LED) by characterizing current-voltage (I–V) characteristics of p-n junction, and two-terminal resistance of p- and n-GaN on both type of layers in LED wafer. Two-terminal resistance on n-GaN kept its initial value after the 1 × 10^14 cm^?2 fluence, and was remained the same order after the 1 × 10^15 cm^?2 fluence. On the other hand, p-GaN showed sensitive increase in two-terminal resistance after the 1 × 10^14 cm^?2, and six orders of increase after the 1 × 10^15 cm^?2 fluence. Observed sensitive increase of resistivity in p-GaN is explained as a lower initial hole density in p-GaN than the initial electron density in n-GaN layer.
关键词： proton irradiation effects,LED,GaN
更新于2025-09-23 15:22:29
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Trapping Analysis of AlGaN/GaN Schottky Diodes via Current Transient Spectroscopy
摘要： Trapping effects on two AlGaN/GaN Schottky diodes with a different composition of the AlGaN barrier layer were analyzed by current transient spectroscopy. The current transients were measured at a constant bias and at six different temperatures between 25 and 150 °C. Obtained data were fitted by only three superimposed exponentials, and good agreement between the experimental and fitted data was achieved. The activation energy of dominant traps in the investigated structures was found to be within 0.77–0.83 eV. This nearly identical activation energy was obtained from current transients measured at a reverse bias of -6 V as well as at a forward bias of +1 V. It indicates that the dominant traps might be attributed to defects mainly associated with dislocations connected predominantly with the GaN buffer near the AlGaN/GaN interface.
关键词： activation energy,exponential function,Schottky diode,AlGaN/GaN,(de)trapping
更新于2025-09-23 15:22:29
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Trap and 1/f-noise effects at the surface and core of GaN nanowire gate-all-around FET structure
摘要： Using capacitance, conductance and noise measurements, we investigate the trapping behavior at the surface and in the core of triangular-shaped one-dimensional (1D) array of GaN nanowire gate-all-around field effect transistor (GAA FET), fabricated via a top-down process. The surface traps in such a low dimensional device play a crucial role in determining the device performance. The estimated surface trap density rapidly decreases with increasing frequency, ranging from 6.07 × 1012 cm?2·eV?1 at 1 kHz to 1.90 × 1011 cm?2·eV?1 at 1 MHz, respectively. The noise results reveal that the power spectral density increases with gate voltage and clearly exhibits 1/f-noise signature in the accumulation region (Vgs > Vth = 3.4 V) for all frquencies. In the surface depletion region (1.5 V < Vgs < Vth), the device is governed by 1/f at lower frequencies and 1/f 2 noise at frequencies higher than ~ 5 kHz. The 1/f 2 noise characteristics is attributed to additional generation–recombination (G–R), mostly caused by the electron trapping/detrapping process through deep traps located in the surface depletion region of the nanowire. The cutoff frequency for the 1/f 2 noise characteristics further shifts to lower frequency of 102–103 Hz when the device operates in deep-subthreshold region (Vgs < 1.5 V). In this regime, the electron trapping/detrapping process through deep traps expands into the totally depleted nanowire core and the G–R noise prevails in the entire nanowire channel.
关键词： gate-all-around field effect transistor (FET),trap,nanowire,GaN,1/f-noise
更新于2025-09-23 15:22:29
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High Channel Conductivity, Breakdown Field Strength, and Low Current Collapse in AlGaN/GaN/Si δ -Doped AlGaN/GaN:C HEMTs
摘要： This paper reports the AlGaN/GaN/Si δ-doped AlGaN/GaN:C HEMT device on silicon with high channel conductivity, high breakdown ?eld (E-?eld) strength, and low current collapse by using the Si-doped AlGaN back barriers. The Si δ-doped AlGaN back barrier was used to compensate for the reduction of channel conductivity as a result of a carbon-doped semiinsulating GaN buffer layer. The maximum drain current increases from 412 to 720 mA/mm, and peak extrinsic transconductance is improved from 103 to 210 mS/mm. Due to the reduction of electric ?eld between the gate and drain along the GaN channel by inserting the Si δ-doped AlGaN back barrier layer, it can effectively suppress the capture of electrons in channel by carbon-induced accepted traps in the GaN:C buffer. Combined with the high conductivity of Si δ-doped AlGaN back barrier and high resistance of GaN:C buffer, the device showed the high breakdown E-?eld strength and the low speci?c on-resistance. Our proposed device is observed to hold a gate–drain voltage of 769 V at 10 μA/mm (7-μm gate–drain spacing) and 0.53 mΩ · cm2 and the gate-to-drain electric ?eld corresponds to 1.1 MV/cm.
关键词： high channel conductivity,high-voltage device,Si δ-doped AlGaN back barrier,GaN,Current collapse (CC)
更新于2025-09-23 15:22:29
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Gate Conduction Mechanisms and Lifetime Modeling of p-Gate AlGaN/GaN High-Electron-Mobility Transistors
摘要： The gate conduction mechanisms in p-gallium nitride (GaN)/AlGaN/GaN enhancement mode transistors are investigated using temperature-dependent dc gate current measurements. In each of the different gate voltage regions, a physical model is proposed and compared to experiment. At negative gate bias, Poole–Frenkel emission (PFE) occurs within the passivation dielectric from gate to source. At positive gate bias, the p-GaN/AlGaN/GaN “p-i-n” diode is in forward operation mode, and the gate current is limited by hole supply at the Schottky contact. At low gate voltages, the current is governed by thermionic emission with Schottky barrier lowering in dislocation lines. Increasing the gate voltage and temperature results in thermally assisted tunneling (TAT) across the same barrier. An improved gate process reduces the gate current in the positive gate bias region and eliminates the onset of TAT. However, at high positive gate bias, a sharp increase in current is observed originating from PFE at the metal/p-GaN interface. Using the extracted conduction mechanisms for both devices, accurate lifetime models are constructed. The device fabricated with the novel gate process exhibits a maximum gate voltage of 7.2 V at t1% = 10 years.
关键词： time-dependent breakdown (TDB),p-GaN gate,high-electron-mobility transistor (HEMT),enhancement mode,gallium nitride (GaN),Conduction mechanism
更新于2025-09-23 15:21:21