GaN Components Research Articles

Integration of Generative-Adversarial-Network-Based Data Compaction and Spatial Attention Transductive Long Short-Term Memory for Improved Rainfall–Runoff Modeling

This work presents a novel approach to rainfall–runoff modeling. We incorporate GAN-based data compaction into a spatial-attention-enhanced transductive long short-term memory (TLSTM) network. The GAN component reduces data dimensions while retaining essential features. This compaction enables the TLSTM to capture complex temporal dependencies in rainfall–runoff patterns more effectively. When tested on the CAMELS dataset, the model significantly outperforms benchmark LSTM-based models. For 8-day runoff forecasts, our model achieves an NSE of 0.536, compared to 0.326 from the closest competitor. The integration of GAN-based feature extraction with spatial attention mechanisms improves predictive accuracy, particularly for peak-flow events. This method offers a powerful solution for addressing current challenges in water resource management and disaster planning under extreme climate conditions.

Temper wolf hunt optimization enabled GAN for robust image encryption

In today’s digital era, the security of sensitive data, particularly in the realm of multimedia, is of paramount importance. Image encryption serves as a vital shield against unauthorized access and ensures the confidentiality and integrity of visual information. As such, the continuous pursuit of robust and efficient encryption techniques remains a pressing concern. This research introduces a Temper Wolf Hunt Optimization enabled Generative Adversarial Network Encryption model (TWHO-GAN), designed to address the challenges of image encryption in the modern digital landscape. TWHO, inspired by the collective hunting behavior of wolf and coyote packs, is employed to generate highly secure encryption keys. This algorithm excels in exploring complex solution spaces, creating robust, attack-resistant keys. In TWHO-GAN model, GANs are employed to create encrypted images that are virtually indistinguishable from their original counterparts, adding a layer of security by generating complex encryption keys and ensuring robust protection against attacks. The GAN component reconstructs the encrypted images to their original form when decrypted with the correct keys, ensuring data integrity while maintaining confidentiality. Further, the significance of the proposed model relies on the TWHO algorithm formulated by the integration of the adaptability and coordinated hunting strategies to optimize the chaotic map generation in image encryption protecting the sensitive visual information from unauthorized access as well as potential threats. Through extensive experimentation and comparative analysis, TWHO-GAN demonstrates superior performance in image encryption, surpassing former methods in terms of Cs, 𝐻𝑖𝑠C, MSE, PSNR, RMSE, and SSIM attaining values of 0.93, 94.19, 3.274, 59.70 dB, 1.8095, and 0.940 respectively for 5 numbers of images. Moreover, the TWHO-GAN approach attained the values of 0.91,92.22, 2.03, 49.74 dB, 1.42, and 0.88 for Cs, HisC, MSE, PSNR, RMSE, and SSIM respectively utilizing the Airplanes dataset. The model exhibits robust resistance to various attacks, making it a compelling choice for secure image transmission and storage.

Enhanced solar-driven photoelectrochemical water splitting using nanoflower Au/CuO/GaN hybrid photoanodes.

Harnessing solar energy for large-scale hydrogen fuel (H2) production shows promise in addressing the energy crisis and ecological degradation. This study focuses on the development of GaN-based photoelectrodes for efficient photoelectrochemical (PEC) water splitting, enabling environmentally friendly H2 production. Herein, a novel nanoflower Au/CuO/GaN hybrid structure was successfully synthesized using a combination of methods including successive ionic layer adsorption and reaction (SILAR), RF/DC sputtering, and metal-organic chemical vapour deposition (MOCVD) techniques. Structural, morphological, and optical characteristics and elemental composition of the prepared samples were analyzed using X-ray diffraction (XRD), scanning electron microscopy (SEM), UV-Vis spectroscopy, and energy-dispersive X-ray (EDX) spectroscopy, respectively. PEC and electrochemical impedance measurements were performed for all samples. The nanoflower Au/CuO/GaN hybrid structure exhibited the highest photocurrent density of ∼4 mA cm-2 at 1.5 V vs. RHE in a Na2SO4 electrolyte with recorded moles of H2 of about 3246 μmol h-1 cm-2. By combining these three materials in a unique structure, we achieved improved performance in the conversion of solar energy into chemical energy. The nanoflower structure provides a large surface area and promotes light absorption while the Au, CuO, and GaN components contribute to efficient charge separation and transfer. This study presents a promising strategy for advancing sustainable H2 production via efficient solar-driven water splitting.

Interface engineering of a GaN/In2O3 heterostructure for highly efficient electrocatalytic CO2 reduction to formate

Electrocatalytic CO2 reduction reaction (eCO2RR) to obtain formate is a promising method to consume CO2 and alleviate the energy crisis. Indium-based electrocatalysts have demonstrated considerable potential to produce formate. However, their unsatisfactory long-term stability and selectivity restrict their widespread application. In this study, a heterostructure of GaN- and In2O3-encapsulated porous carbon nanofibers was constructed via electrospinning and the phase transition of eutectic gallium-indium during calcination. The GaN and In2O3 nanoparticle-encapsulated porous carbon nanofibers, when used as electrocatalysts for eCO2RR, displayed high formate selectivity with a faradaic efficiency of 87% and maximum partial current density of 29.7 mA cm−2 in a 0.5 mol L−1 KHCO3 aqueous solution. The existence of the interface can cause a positive shift in the In 3d binding energy, leading to electronic redistribution. Moreover, the GaN component induced a higher proportion of O-vacancy sites in the In2O3 phase, resulting in improved selectivity for CO2-to-formate. In-situ Raman experiments and density functional theory calculations revealed that the interface between GaN and In2O3 could lower the adsorption energy of the key intermediates for formate production, thus providing superior eCO2RR performance. In addition, the framework of the porous carbon nanofibers exhibited a large electrochemically active surface area, which enabled the full exposure of the active sites. This study highlights the cooperation between GaN and In2O3 components and provides new insights into the rational design of catalysts with high CO2-to-formate conversion efficiencies.

Pre-sizing of a modular high power density DC/DC converter with GaN components

Finding the most appropriate architecture to achieve a function is a major engineering challenge. In the power conversion context, the question that arises is: what is the best trade-off between an architecture based on a single high-power converter and another based on the combination of multiple low-power converters? This article aims to answer this question in the specific case of the isolated interface between the low voltage (28VDC) and high voltage (±270VDC) buses of an aircraft. Towards this goal, the targeted power electronics converter is carefully modeled in order to obtain an accurate and fast computing model. A technological database of the different usable components is then used to feed an optimization algorithm. The execution of the latter achieves an attractive and robust result showing an excellent performance in terms of power-to-weight ratio, which is the key index of this study. The precision and speed of this computer-aided design is based on analytical models that are quick to run and therefore enable exploring almost exhaustively the search space. More specifically, the high-frequency transformer has a large relative mass and generates significant losses that are difficult to assess. A major modeling effort has been undertaken and has been enabled to define a simplified but convincing and accurate model (successfully assessed on a wide bandwidth using an experimental setup). It was used for the first time in this optimization process. According to the targeted aeronautical specifications, the two best solutions would make it possible to achieve a mass power density of 4.5kW/kg, i.e. twice as high as traditional solutions. This result very clearly shows that the appropriate use of the new GaN transistors makes it possible to make a technological breakthrough. Considering the voltage and current ratings of these components, this shows that the combination of multiple partial converters is very promising and will make it possible in the future to achieve a significant increase in the compactness of electrical power conversion functions. This sizing study therefore clearly shows the potential of the standardized design of power electronics converters and the search for the best combinations (series, parallel) to meet any specific specifications. Additionally, the developed approach, based on a modeling effort, especially as far as the high-frequency transformer is concerned, and collection of manufacturer data, also makes it possible to limit the implementations and associated tests.Hence, the main contributions of this article are (i) the assembly of the analytical models of the various components constituting an isolated DC–DC power supply, (ii) the simplification of an analytical model of the planar HF transformer, its experimental validation and its first use in a loop of optimization, (iii) the fact of showing supporting figures that GaN technology enables technological breakthroughs to achieve high power density, which opens the way to modular architectures based on partial converters of electrical power, (iv) the comprehensive description of a powerful pre-study design tool enabling to greatly reduce power converters’ time to market.

Comparison of GaN Enhancement Mode Transistor Performance With Integrated and External Driver

GaN components allow to reduce power losses as the lower specific on-resistance and higher switching speeds reduce both the conduction and switching loss. However, parasitics in the gate loop cause ringing which endangers the component. To counteract these problems the switching speed is lowered renouncing part of the components superior performance. A possible way to avoid gate loop parasitics and make circuit design less challenging is integrating the driver in the same package with the GaN transistor. In this paper the performance of an integrated driver with enhancement mode GaN half-bridge that is monolithically integrated using IMEC GaN-on-SOI will be tested in a synchronous boost converter setup. Converter efficiency and switching waveforms will be reported together with a comparison to a GaN half-bridge with external drivers. The converter is tested at input voltages up to 50 V and powers up to 100 W. Package temperature measurements are included to estimate the influence of the temperature dependent on-resistance on the results. At the end of the paper, a sensitivity analysis is conducted to quantify the behaviour of the losses in function of different input parameters including a measurement at switching frequencies up to 1MHz.

Toward efficient long-wavelength III-nitride emitters using a hybrid nucleation layer.

The realization of efficient III-nitride emitters in the green-to-amber region is fundamental to the monolithic integration of multicolor emitters and the development of III-nitride-based full-color high-resolution displays. A hybrid nucleation layer, which includes sputtered AlN and mid-temperature GaN components, was proposed for the development of efficient III-nitride emitters in the green-to-amber region. The mid-temperature GaN component in the hybrid nucleation layer induced the formation of a stacking fault band structure, which effectively relaxed the misfit stress at the GaN/sapphire interface. A reduced dislocation density and in-plane compressive stress in InGaN/GaN multiple quantum wells were obtained on the hybrid nucleation layer in comparison with the conventional sputtered AlN nucleation layer. Consequently, a significantly enhanced internal quantum efficiency and improved light output power were achieved for the LEDs grown on the hybrid nucleation layer. This gain is attributed to the increased localization depth and spatial overlapping of the electron and hole wave functions. In the present study, the hybrid nucleation layer provides a promising approach for the pursuit of efficient III-nitride emitters in the green-to-amber region.

A Very High Frequency Self-Oscillating Inverter Based on a Novel Free-Running Oscillator

This letter introduces a self-oscillating very high-frequency (VHF) class $\phi$ 2 inverter based on a free-running oscillator. The class $\phi$ 2 is a low-voltage semiconductor stress, fast-transient, single-transistor inverter topology suitable for VHF applications. With new advancements in GaN technology, the tendency to increase the switching frequency in power converters is on the rise. Switching at VHF (VHF: 30–300 MHz) allows for smaller passive components and more compact power converters. However, although GaN components are able to switch at 100 MHz and beyond, gate drivers available in the market struggle to provide the adequate switching signal at VHF. Hence, there is a need for an alternative to VHF converters using those gate drivers—self-oscillating topologies. To that end, a self-oscillating class $\phi$ 2 inverter switching at 30 MHz is presented and a design methodology is provided. A 30 MHz prototype with 30 V input voltage using a GaN Systems GS61004B is also built and tested, showing good matching between the simulation and experimental results.

Immiscibility behind the metalorganic vapor phase epitaxy of InGaN

The vapor–solid phase equilibrium and the solid composition versus input group-III ratio relationship for the metalorganic vapor phase epitaxy of InGaN are analyzed on the basis of standard thermodynamics. Immiscibility is inherent in the activities of the InN and GaN components. A miscibility gap (MG) definitely appears in the vapor–solid phase equilibrium below the critical temperature. At a given temperature, the equilibrium partial pressures are fixed at those for the binodal compositions across the MG. In the solid composition versus input group-III ratio diagram, the MG at a given temperature is represented by a straight line which gives a weighted average of the binodal compositions for a given input group-III ratio. The apparently uniform compositions observed in low-temperature growth may be attributed to the non-equilibrium “freeze-out” effect of the growth species due to the slow surface kinetics.

DC-DC converter with GaN transistor and coupled with monolithic ICT sintered by PECS/SPS

ABSTRACTThis paper presents an implementation of the voltage regulator module (VRM) DC-DC converter operating at 2 MHz using three interleaved switching cells whose outputs are magnetically coupled by monolithic intercell transformers (ICT). The innovation comes from the manufacturing of the ICTs. Spinel ferrite is sintered around two copper windings by pulsed electric current sintering (PECS), also called spark plasma sintering (SPS). The manufacturing processes are detailed in this paper, and the ICTs magnetic properties are measured. The high-frequency operation of the converter has been possible thanks to the implementation of GaN components. The power density of the converter is 15 kW/dm3.

Broadband push-pull power amplifier design methodology based on the GaN component base for high-performance nonlinear junction detectors

The paper presents a description of design methodology for wide-band push-pull large-signal power amplifier based on GaN transistor with an output power of more than 10 W for high-performance Nonlinear Junction Detectors, which allows achieving optimal convergence of the theoretical model in practice, as well as increasing the efficiency of the power amplifier while maintaining a linear gain characteristic.

Evaluation of novel carrier substrates for high reliability and integrated GaN devices in a 200 mm complementary metal-oxide semiconductor compatible process

Abstract

Structural defects of GaN deposited on (111) Si with Gd2O3-related buffer layers

The structural defects of GaN deposited on (111) Si with Gd2O3-related rare earth oxide buffer layers were investigated using a double-crystal x-ray rocking curve (DCXRC), high resolution transmission electron microscopy (HRTEM). By comparing the DCXRC signals of (11¯02)GaN and (12¯12)GaN asymmetric planes and (0002)GaN symmetric plane, respectively, it was found that most of the threading dislocations (TDs) in GaN of the GaN on (111) Si using Gd2O3 or Er2O3/Gd2O3 buffer layer are type a TDs in nature. Based on the results of DCXRC studies, it is believed that the full-width at half maxima of the DCXRC signals of (11¯02)GaN and (12¯12)GaN asymmetric planes are primarily due to the contributions of the 1/3⟨12¯10⟩GaN components of the Burgers vectors of type a and type c + a TDs on the interplanar spacing distortions of (11¯02)GaN and (12¯12)GaN planes in GaN of the GaN/Er2O3/Gd2O3/(111) Si samples. HRTEM observations also revealed the presence of extrinsic stacking faults and Frankel partial dislocations in GaN of the GaN on the (111) Si sample with Gd2O3 or Er2O3/Gd2O3 buffer layer.

One-pot simple synthesis and characterisation of Mn2+-doped GaN nanorods by RAPET method

In this work, we display one-step reactions under autogenic pressure at elevated temperature (RAPET) method-based synthesis of Mn-doped GaN nanorods by varying the atomic ratio of Mn:Ga as 0, 0.02, 0.04, 0.06 and 0.08, respectively. The synthesised nanorods are characterised by X-ray diffraction, high-resolution transmission electron microscopy (HRTEM) and Raman spectral methods. It is observed that there is a decrease in the lattice constant with an increase in the concentration of Mn (from 0.02 to 0.08 wt%). Moreover, the smaller covalent radius of Mn is the key for the doping process. The Mn-doped GaN nanocrystals show rod-like morphology with a length of 40–50 nm and width of 8–12 nm. This size factor mainly depends on the doping of Mn [from transmission electron microscopy (TEM) analysis] into GaN components. Well-defined lattice fringes are elucidated for the growth of crystalline hexagonal GaN (wurtzite type) nanocrystals.

A computer study of the Raman spectra of the (GaN)129, (SiO2)86, and (GaN)54(SiO2)50 nanoparticles

The Raman spectra of the (GaN)129, (SiO2)86, and (GaN)54(SiO2)50 nanoparticles were calculated using the molecular dynamics method. The spectrum of (SiO2)86 had three broad bands only, whereas the Raman spectrum of (GaN)129 contained a large number of overlapping bands. The form of the Raman spectrum of (GaN)54(SiO2)50 was determined by the arrangement of the GaN and SiO2 components in it. The nanoparticle with a GaN nucleus had a continuous fairly smooth spectrum over the frequency range 0 ≤ ω ≤ 600 cm−1, whereas the spectrum of the nanoparticle with a SiO2 nucleus contained well-defined bands caused by vibrations of groups of atoms of different kinds and atoms of the same kind.

Photoluminescence Spectroscopic and Computational Investigation of the Origin of the Visible Light Response of (Ga1−xZnx)(N1−xOx) Photocatalyst for Overall Water Splitting

The electronic structure of a solid solution between GaN and ZnO, GaN-rich (Ga1−xZnx)(N1−xOx), was investigated by photoluminescence spectroscopy and a plane wave based density functional method. Photoluminescence excitation spectra (PLE) of (Ga1−xZnx)(N1−xOx) photocatalysts (x = 0.05−0.11) at 20 K had PLE edges in the UV region in addition to those of undoped GaN and Zn-doped GaN. However, the absorption edges appeared in the visible region, indicating that the intrinsic band gap of GaN-rich (Ga1−xZnx)(N1−xOx) solid solutions is derived from that of the GaN component. Photoluminescence (PL) bands of (Ga1−xZnx)(N1−xOx) photocatalysts were observed at 480 and 650 nm, suggesting that the luminescence originated from electron transitions from the conduction band to Ga vacancies as native defects, or to Zn acceptor levels as impurity levels. GaN-rich (Ga1−xZnx)(N1−xOx) material containing a large amount of oxygen is likely to produce an O donor level slightly below the conduction band minimum (CBM). The Zn ac...

Thermodynamic modeling of the Ni–Al–Ga–N system

Isothermal sections in the Ni–Al–Ga–N quaternary phase diagram were calculated to provide a greater understanding of interfacial reactions between Ni contacts and AlxGa1−xN. The calculations were performed employing a thermodynamic database of the Ni–Al–Ga–N system that was constructed by combining the six binary systems of the four component system. The model of the Ga–N binary system was created in this work. The models of the Ni–Ga and Ni–Al systems, both of which were taken from the literature, were modified to be compatible with one another. Thermodynamic data and phase boundaries for other binary systems were taken from the literature, as was information on portions of the Al–Ga–N and Ni–Al–Ga phase diagrams. The calculated sections reveal that during reaction between Ni and AlxGa1−xN, Ni is favored to react with the GaN component of the semiconductor alloy, leaving an Al-enriched AlxGa1−xN. These predictions are consistent with a recent analysis of the Ni, Al, and Ga elemental distributions across the interface between a Ni thin film and an Al0.47Ga0.53N epitaxial layer following annealing at 850 °C. Consideration of the thermodynamic driving forces suggests that this may be a general phenomenon existing in other metal–Al–Ga–N systems.

Vapor-phase epitaxy of InxGa1−xN using chloride sources

The growth kinetics of InxGa1−xN epitaxial layer on GaN-buffer/sapphire (0001) substrate and the vapor–solid distribution relationship of the chloride source system are investigated. The growth rate decreases with increasing growth temperature. The solid composition of epitaxial layers becomes more GaN-rich with the increasing growth temperature and is very sensitive to the H2 mole reaction in the carrier gas. In the vapor–solid distribution relationship, the preferential incorporation of the GaN component is observed. The indium droplets are not observed on the surface of InxGa1−xN films in the entire composition range. Without In droplets formation, the In-rich InxGa1−xN alloys as high as 0.8 of In content are obtained.