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[IEEE 2018 IEEE 7th Global Conference on Consumer Electronics (GCCE) - Nara, Japan (2018.10.9-2018.10.12)] 2018 IEEE 7th Global Conference on Consumer Electronics (GCCE) - Eye Gaze Correction Using Generative Adversarial Networks
摘要： Eye gaze correction is an important topic in video teleconference and video chart in order to keep the eye contact. In this paper, we propose to use a generative adversarial networks for eye gaze correction. We use pairs of front facial image (idea camera setting) and real facial image (real camera setting) to training the network. By using the trained network, we can generate a gaze corrected facial image (front facial image) for any real facial image. Experiments demonstrated the effectiveness of our proposed method.
关键词： Generative Adversarial Net(GAN),image-to-image translation,deep learning,gaze correction,Conditional GAN
更新于2025-09-04 15:30:14
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[Advances in Imaging and Electron Physics] || AlN/GaN and InAlN/GaN DBRs
摘要： This chapter presents the high resolution monochromated STEM-EELS characterization of two distributed Bragg re?ector (DBR) multilayer heterostructures, composed of a periodic staking of III-nitride layers. These heterostructures were grown by the group of E. Calleja at the Instituto de Sistemas Optoelectrónicos y Microtecnología (ISOM), from Universidad Politéc- nica de Madrid. One of these DBR is composed of an alternate staking of AlN and GaN layers, and the other one, of InAlN lattice matched to GaN. EELS at sub-nanometric spatial resolution and < 200 meV energy resolution was used to assess the electronic properties of the structures. The EELS signal was treated using ZLP subtraction and deconvolution methods, and non-linear ?tting tools complemented with theoretical modeling of the electron scattering distribution. In this sense, the log-ratio formula was used to calculate the relative thickness, related to the electron inelastic mean free path. Moreover, ?tting of the bulk plasmon peak was performed using Lorentzian and Drude free-electron models. As we have seen, in group-III nitride alloys, the energy position of this peak can be related to the chemical composition variation through Vegard’s law. Also, within the context of the Drude plasmon model, information regarding the structural properties of the material can be obtained from the lifetime of the oscillation. This structural and chemical characterization of the layers was complemented with experimental and simulated high angle annular dark ?eld (HAADF) images. Finally, information related to the dielectric response of the mate- rials was extracted using Kramers–Kronig analysis. Our results signi?cantly improve the understanding of previous macroscopic characterizations of the electro-optical properties of these structures.
关键词： AlN/GaN,InAlN/GaN,Kramers–Kronig analysis,STEM-EELS,Vegard’s law,plasmon peak,DBRs
更新于2025-09-04 15:30:14
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[IEEE 2018 IEEE Energy Conversion Congress and Exposition (ECCE) - Portland, OR, USA (2018.9.23-2018.9.27)] 2018 IEEE Energy Conversion Congress and Exposition (ECCE) - Stretching in Time of GaN Active Gate Driving Profiles to Adapt to Changing Load Current
摘要： Active gate driving, where the gate signal is actively profiled, has been shown to reduce EMI, overshoot, and switching loss, in silicon power converters. Recently, much faster gate drivers with the ability to profile at a 100 ps resolution have been reported, which has opened up the possibility of actively driving emerging wide-bandgap devices. This could allow Gallium Nitride (GaN) and Silicon Carbide (SiC) FETs to be switched faster than is currently possible, as unwanted switching features such as current ringing at turn-on could be eliminated. However, these drivers have previously only been demonstrated with pre-programmed gate profiles that have been optimized at certain operating conditions, whereas converters typically operate in a range of conditions. In this paper, some limitations of using fixed gate profiles on GaN FETs are reported for the first time, and a new method of profile adaptation is demonstrated. First, the gate profiles in a 400 V GaN bridge-leg are optimized to minimize current ringing at turn-on for a given load current. Then, the load current is varied, showing that the gate signal profile remains close to optimal for ±20% changes in current. Also, over a larger range of at least ±35%, the profiled waveform performs better than a non-profiled gate waveform. It is then demonstrated that by slightly reducing the driver’s internal clock frequency with increasing load current, the profile is re-optimized for new load currents. It is concluded that driver clock frequency adaptation may be a means of adapting gate profiles to load current variation and possibly also to temperature variation.
关键词： Active Gate Driving,Arbitrary Waveform Gate Driver,GaN Gate Driver,Dynamic Output Resistance Gate Driver,GaN FET
更新于2025-09-04 15:30:14
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X-Band GaN High Electron Mobility Transistor Power Amplifier on 6H-SiC with 110 W Output Power
摘要： High quality AlGaN/AlN/GaN high electron mobility transistors (HEMTs) were grown on 3-inch diameter semi-insulating 6H-SiC substrates by metal organic chemical vapor deposition. The GaN HEMT wafer exhibited an average sheet resistance of 342.2 Ω/□ with a uniformity of 1.5% by introducing both the high mobility GaN channel layer and AlN interlayer. At room temperature a Hall mobility of 2412.06 cm2/Vs and a two-dimensional electron gas density of 7.654 × 1012 cm?2 are achieved. Atomic force microscopy showed a smooth surface and a root-mean-square roughness of 0.227 nm for 10 × 10 μm2 scan area. Direct current measurements revealed a maximum drain current density of 1.31 A/mm and an extrinsic transconductance of 450 mS/mm. The current gain cutoff frequency and maximum frequency of oscillation of the device were measured to be 31 GHz and 60 GHz, respectively. Eight-cell internally-matched GaN HEMT device exhibited a maximum continuous-wave output power of 110.9 W at 8 GHz, with a power-added efficiency of 33.7% and a power gain of 6.35 dB.
关键词： X-Band,Power Amplifier,GaN HEMT
更新于2025-09-04 15:30:14
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Thermal management and characterization of high-power wide-bandgap semiconductor electronic and photonic devices in automotive applications
摘要： GaN-based high-power wide-bandgap semiconductor electronics and photonics have been considered as promising candidates to replace conventional devices for automotive applications due to high energy conversion efficiency, ruggedness, and superior transient performance. However, performance and reliability are detrimentally impacted by significant heat generation in the device active area. Therefore, thermal management plays a critical role in the development of GaN-based high-power electronic and photonic devices. This paper presents a comprehensive review of the thermal management strategies for GaN-based lateral power/RF transistors and light-emitting diodes (LEDs) reported by researchers in both industry and academia. The review is divided into three parts: (1) a survey of thermal metrology techniques, including infrared thermography, Raman thermometry, and thermoreflectance thermal imaging, that have been applied to study GaN electronics and photonics, (2) practical thermal management solutions for GaN power electronics, and (3) packaging techniques and cooling systems for GaN LEDs used in automotive lighting applications.
关键词： semiconductor,Raman thermometry,infrared thermography,high-power,automotive applications,LEDs,thermoreflectance thermal imaging,GaN,thermal management,wide-bandgap
更新于2025-09-04 15:30:14
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Fabrication of GaOx Confinement Structure for InGaN Light Emitter Applications
摘要： An indium gallium nitride (InGaN) light-emitting diode (LED) with an embedded porous GaN reflector and a current confined aperture is presented in this study. Eight pairs of n+-GaN:Si/GaN in stacked structure are transformed into a conductive, porous GaN/GaN reflector through an electrochemical wet-etching process. Porous GaN layers surrounding the mesa region were transformed into insulating GaOx layers in a reflector structure through a lateral photoelectrochemical (PEC) oxidation process. The electroluminescence emission intensity was localized at the central mesa region by forming the insulating GaOx layers in a reflector structure as a current confinement aperture structure. The PEC-LED structure with a porous GaN reflector and a current-confined aperture surrounded by insulating GaOx layers has the potential for nitride-based resonance cavity light source applications.
关键词： insulating GaOx,current confinement aperture structure,porous GaN,InGaN
更新于2025-09-04 15:30:14
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Impact of Al Pre-Deposition Layer on Crystalline Quality of GaN Grown on Si(111) Substrates
摘要： The effects of Al metal pre-deposition under different conditions on GaN grown on Si(111) substrates by metal-organic chemical vapor deposition (MOCVD) have been investigated. Al pre-deposition improves surface morphology and crystal quality of GaN grown on Si. The surface morphology of Al pre-deposition layer, AlN, and GaN vary depending on Al pre-deposition temperature. With the increase of Al pre-deposition temperature, Al cluster size is observed to increase in the Al pre-deposition layer due to increased lateral mobility of Al atoms. The Al pre-deposition carried out at about 750 °C enables to grow pit-free GaN layer on Si(111) substrate.
关键词： GaN,Al Pre-Deposition,MOCVD,Silicon
更新于2025-09-04 15:30:14
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First-principles study of polar, nonpolar, and semipolar GaN surfaces during oxide vapor phase epitaxy growth
摘要： Stable structures of polar, nonpolar, and semipolar GaN surfaces undergoing oxide vapor phase epitaxy (OVPE) growth were examined with first-principles calculations. The relationships between temperature and pressure growth conditions and stable surface structures are described in surface phase diagrams. The results revealed that an O atom was stably incorporated into the N vacancy site in the N-polar and nonpolar surfaces. The desorption energy of the O atom from the GaN surfaces was estimated to be about 7 eV or higher. This indicates that the O atom did not readily desorb from the GaN surfaces under OVPE growth conditions at 1500 K. The desorption energy from the e000 (cid:2)1T surface was the highest and that from the e10 (cid:2)1 (cid:2)1T surface was the smallest among the calculated values. There was no significant difference in desorption energy among other surfaces.
关键词： first-principles calculations,desorption energy,OVPE,surface phase diagrams,GaN
更新于2025-09-04 15:30:14
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Sulfur Incorporation at Interface Between Atomic-Layer-Deposited Al2O3 Thin Film and AlGaN/GaN Heterostructure
摘要： Surface incorporation at the interface between atomic-layer-deposited Al2O3 thin film and AlGaN/GaN heterostructure was studied based on the understanding of charge configuration and electronic band structure through fabrication and numerical simulation. The annealing in H2S ambient at various temperatures prior to deposition of Al2O3 gate insulator incorporated the sulfur. The Al2O3 was formed on the sulfur treated GaN cap/AlGaN barrier/GaN by trimethylaluminum and water-based atomic layer deposition. Thereafter, TiN electrode was sputtered on the Al2O3, which was followed by forming gas annealing. The time-of-flight secondary ion mass spectroscopy disclosed that the sulfur located at the interface of Al2O3/GaN cap, of which concentration increased with annealing temperature. Positive charges at the interface of Al2O3/GaN cap induced by sulfur increased the two-dimensional electron gas density and shifted the pinch-off voltage in the negative direction. The diffusion of sulfur in the GaN cap and AlGaN barrier can hamper the electron accumulation under positive gate voltage and shifts the accumulation voltage of the spillover region in the positive direction. Furthermore, the incorporated sulfur suppressed the gate leakage current.
关键词： H2S,Dielectrics,GaN,Sulfur annealing,Interface,AlGaN
更新于2025-09-04 15:30:14
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High-efficiency electron-beam-pumped sub-240-nm ultraviolet emitters based on ultra-thin GaN/AlN multiple quantum wells grown by plasma-assisted molecular-beam epitaxy on <i>c</i> -Al <sub/>2</sub> O <sub/>3</sub>
摘要： We report the internal structures and emission properties of GaN/AlN single- and multiple-quantum-well (QW) heterostructures with well widths of dw = 1–4 monolayers (MLs), grown by plasma-assisted molecular-beam epitaxy on c-sapphire at metal-rich conditions and low temperatures (>700 °C). The formation of plane QWs with abrupt symmetrical interfaces is con?rmed by both scanning transmission electron microscopy and X-ray di?raction analysis. Pulse-scanning and continuous-wave output powers of 150 and 28 mW, respectively, at a peak emission wavelength of 235 nm were achieved at 300 K in an electron-beam-pumped deep-ultraviolet (1.5 ML-GaN/5.5 nm-AlN)360 multiple-QW emitter with a maximum e?ciency of 0.75%.
关键词： plasma-assisted molecular-beam epitaxy,electron-beam-pumped,deep-ultraviolet emitters,GaN/AlN,quantum wells
更新于2025-09-04 15:30:14