High Power Electronic Devices Research Articles

Spherical Fe3O4 morphology modulation for enhancing infrared emissivity and radiant heat dissipation

Radiant heat dissipation has emerged as a critical technique for effective thermal management, offering energy efficiency, cost-effectiveness, and adaptability to various shapes while promoting environmental sustainability. However, the intricate relationship between material structures and emissivity remains inadequately understood. This study primarily utilizes a straightforward and economical solvothermal method to regulate the synthesis of Fe3O4 ferrite, exploring its structural relationship with infrared radiation performance. By adjusting the solvent ratio of ethylene glycol and diethylene glycol in the solvothermal system, we successfully synthesized uniformly dispersed Fe3O4 nanospheres ranging from 10 to 800 nm. Notably, our research revealed a positive correlation between infrared emissivity and the particle size. Submicron hollow spheres with a size of 800 nm exhibit an exceptionally high emissivity of 0.992 within the 8∼13 μm wavelength range. Morphological and size variations induced alterations in lattice strain, oxygen vacancies, and phonon lifetimes, which consequently influencing the lattice vibration absorption and infrared emissivity. Moreover, the device surface with a composite coating formed by combining 15wt% Fe3O4 particles with organic matter, achieves a temperature difference of 17.6 °C under a 4 W input power condition compared to blank device. This finding contributes to further revealing the process of material radiative heat dissipation, driving the application of high-emissivity materials for heat dissipation in high-power electronic devices.

Random Vibration Fatigue Life Prediction of Nano-Silver Solder Joint

Nano-silver is a very potential electronic interconnection material. It’s excellent physical and chemical properties, high thermal conductivity and good electrical conductivity make it very suitable for high power electronic devices. In practical engineering, 20% of the failure of electronic products is caused by vibration load, so it is necessary to study the vibration reliability of interconnected materials. In this paper, the modal and random vibration finite element analysis of nano-silver solder joints were analyzed with workbench software. Predicting random vibration fatigue life of nano-silver solder joint by Coffin-Manson high cycle fatigue empirical formula, Miner’s linear cumulative damage theory and Steinberg model. The random vibration fatigue life of the nanosilver solder joint is 8342 h. It is found that the vibration reliability of nano-silver is inferior to Sn3.0Ag0.5Cu and Sn63Pb37 and the diameter of solder joints and PCB thickness are proportional to the vibration fatigue life, and the PCB thickness has a greater effect on the vibration life than the solder joint diameter. Solder joint height and pad thickness are inversely proportional to vibration fatigue life, and pad thickness has little effect on vibration fatigue life.

Interfacial Optimization for AlN/Diamond Heterostructures via Machine Learning Potential Molecular Dynamics Investigation of the Mechanical Properties.

AlN/diamond heterostructures hold tremendous promise for the development of next-generation high-power electronic devices due to their ultrawide band gaps and other exceptional properties. However, the poor adhesion at the AlN/diamond interface is a significant challenge that will lead to film delamination and device performance degradation. In this study, the uniaxial tensile failure of the AlN/diamond heterogeneous interfaces was investigated by molecular dynamics simulations based on a neuroevolutionary machine learning potential (NEP) model. The interatomic interactions can be successfully described by trained NEP, the reliability of which has been demonstrated by the prediction of the cleavage planes of AlN and diamond. It can be revealed that the annealing treatment can reduce the total potential energy by enhancing the binding of the C and N atoms at interfaces. The strain engineering of AlN also has an important impact on the mechanical properties of the interface. Furthermore, the influence of the surface roughness and interfacial nanostructures on the AlN/diamond heterostructures has been considered. It can be indicated that the combination of surface roughness reduction, AlN strain engineering, and annealing treatment can effectively result in superior and more stable interfacial mechanical properties, which can provide a promising solution to the optimization of mechanical properties, of ultrawide band gap semiconductor heterostructures.

Numerical investigation of jet impingement on flat/concave cooling of CO2 with different phase states under high heat flux

The thermal load and high temperature brought by the increase in power of electronic devices or the increase in speed of supersonic aircraft limit the respective development. In this paper, a numerical model of CO2 jet impingement cooling of a constant heat flux plate/concave surface in different phase states was established. Secondly, the non-equilibrium phase transition and the real-thermophysical properties of CO2 was considered. The effects of different wall heat flux (0.7 MW/m2 ∼ 6.5 MW/m2) and initial phase states on the impact cooling performance of CO2 jet were studied.It is found that for SCO2 jet impingement, when the inlet temperature is lower than the pseudo-critical temperature, the heat transfer coefficient increases with the increase of inlet pressure, and the maximum increase is 24.7 %. For near-critical liquid CO2 (LCO2) jet impingement, low latent heat prevents temperature overshoot in the heat flux range studied. With the increase of the proportion of dry ice in the inlet, the heat transfer coefficient also increases. When q > 3 MW/m2, the heat transfer coefficient of dry ice jet impact is 2.5 ∼ 3 times and 1 ∼ 1.4 times of that of SCO2 and near-critical LCO2 jet impingement for the flat plate model, respectively. For concave surface with high heat flux, near-critical LCO2 jet impingement cooling effect is relatively good. In addition, concave surface will aggravate the uneven cooling surface temperature.The results can provide more references for the CO2 jet impingement technology in the design of stagnation cooling system of supersonic aircraft and thermal management of high-power electronic devices.

Advancements and challenges in BaTiO3-Based materials for enhanced energy storage

Numerous researchers worldwide have been motivated to develop highly effective, environmentally acceptable green energy sources as a result of the recent sharp increase in energy use and the need for low emission levels. The energy generated from various renewable sources can be stored efficiently with a system that has a high energy density and high energy efficiency. Due to their enhanced dielectric, ferroelectric, and breakdown strength characteristics, BaTiO3 based dielectric/ferroelectric ceramic materials have received a lot of interest for energy storage applications in the past tw decades. In the present work, a thorough analysis of recent advancements in composites and single-phase BaTiO3 materials with enhanced energy storage performance. This review's main focus is on the crucial tactics and theoretical frameworks for improving the energy efficiency and recovered energy storage density of various BaTiO3-based materials. A thorough summary has been provided with the most recent developments in BaTiO3 based materials for multi-layered ceramic capacitors (MLCCs), pulse power capacitors, piezoelectric transducers, energy harvesting, electric vehicle batteries, and high-power electronic devices in order to confirm the commercial applications of BaTiO3 based single phase as well as multi-phase layered structures and composites.

Construction of 3D BN network with high-density thermal conductive paths

Efficient heat dissipation is essential to further improve the integration of high-power electronic packaging devices. Three-dimensional BN networks with high-density thermal conductive paths were designed as the heat transfer skeleton of thermal interface materials. 3D networks with high-density thermal conductive paths inlaid between oriented BN paths were constructed using precursor self-assembly and freeze-drying to improve the thermal conductivity of polymeric materials. The results show that high-density thermally conductive paths have stronger polymer-enhanced thermal conductivity than directional thermal paths and compared with pure TPU, the thermal conductivity of TPU/BN-2 under low BN filling content (10%wt) is increased by 250 % and 286.5 % in the through surface and flat surface respectively. This work provides new ideas for the preparation of polymer composites for thermal interface materials in electronic packaging and integrated circuits with excellent thermal management properties.

The internal modified layer structure of silicon carbide induced by ultrafast laser and its application in stealth dicing

Silicon carbide (SiC) is widely applied in high-power electronic devices due to its excellent properties. Stealth dicing (SD) as one of the dicing methods, exhibits the advantages of few thermal surface damage and low edge-chipping. In this study, we use an ultrafast laser to induce the modified layer structure inside the SiC wafers. The effects of laser processing parameters on the modified layers are studied. The formation mechanism of the modified layer and its influence on SD are analyzed. The result shows that the number of modified layer structures is mainly determined by the moving velocity. The different modified layer structures will affect the surface roughness of the SD cross-section and critical fracture load of the 4H-SiC wafers. Finally, we achieved the high-quality SD of SiC wafers, and a cross-section with the minimum surface roughness is approximately 381 nm.

Dynamic Response of Phase Change Heat Exchange Unit with Layered Porous Media for Pulsed Electronic Equipment

Effective heat dissipation challenges transient high-power electronic devices in hypersonic vehicle cabins. This study introduces a Phase Change Heat Exchange Unit with Layered Porous Media (PCHEU–LPM) employing pulsed heat flow at the top and forced convection at the bottom. The primary aim was a comparative parametric study analyzing the thermal response of the heating surface under pulsed heat flow conditions. The geometric model was generated using electron microscopy images of manufactured objects and the numerical model was established based on the enthalpy–porosity method. Numerical simulations explored amplitude and frequency effects on pulsed thermal excitation, evaluating temperature and phase fields. A comprehensive time-frequency transformation assessed the temperature response. The results indicated an initial decrease and subsequent increase in interface temperature fluctuation with pulse heat flux amplitude growth. Temperature field uniformity correlated with natural convection strength in two-phase and liquid-phase regions. At mid and low frequencies, the phase change process increasingly suppressed interface temperature fluctuations. Optimal pulse thermal excitation selection was crucial for minimizing temperature fluctuations while maintaining the interface temperature within the expected phase transition range. In conclusion, a novel design concept is posited herein, aiming to enhance surface temperature uniformity and broaden the applicability of electronic devices through the manipulation of porosity rates.

Prediction of phonon properties of cubic boron nitride with vacancy defects and isotopic disorders by using a neural network potential

Cubic boron nitride (c-BN) is a promising ultra-wide bandgap semiconductor for high-power electronic devices. Its thermal conductivity can be substantially modified by controlling the isotope abundance and by the quality of a single crystal. Consequently, an understanding of the phonon transport in c-BN crystals, with both vacancy defects and isotopic disorders at near-ambient temperatures, is of practical importance. In the present study, a neural network potential (NNP) for c-BN has been developed, which has facilitated the investigation of phonon properties under these circumstances. As a result, the phonon dispersion and the three- and four-phonon scattering rates that were predicted with this NNP were in close agreement with those obtained from density-functional theory (DFT) calculations. The thermal conductivities of the c-BN crystals were also investigated, with boron (B) vacancies ranging from 0.0% to 0.6%, by using equilibrium molecular dynamics simulations based on the Green-Kubo formula. These simulations accurately capture vacancy-induced phonon softening, localized vibration modes, and phonon localization effects. As has previously been experimentally prepared, four isotope-modified c-BN samples were selected for analyses in the evaluation of the impact of isotopic disorders. The calculated thermal conductivities aligned well with the DFT benchmarks. In addition, the present study was extended to include a c-BN crystal with a natural abundance of B atoms, which also contained B vacancies. Reasonable thermal conductivities and vibrational characteristics, within the temperature range of 250–500 K, were then obtained.

Experimental investigation of two-phase immersion cooling with single and multi-fluid systems

ABSTRACT Two-phase immersion cooling has emerged as a promising solution for efficient and effective thermal management in high-performance computing applications. This study presents the results of detailed experimental investigations on two-phase immersion cooling via pool boiling employing single-fluid and multi fluids in the system. In the proposed multi-fluid system, two immiscible fluids are stacked in series without a solid interface separating them. NOVEC 7100 is used as the boiling fluid where the heater is fully immersed, and deionized water serves as the condensing fluid. The results show that both single and multi-fluid immersion cooling systems are able to effectively cool high-power electronic devices. However, the multi-fluid system demonstrates superior cooling performance compared to the single-fluid system, owing to its enhanced heat transfer capabilities. The multi-fluid system has a superior overall heat transfer coefficient with an average increase of 33.3% compared to the single-fluid system. The findings of this study contribute to the understanding and optimization of future multi-fluid two-phase immersion cooling systems.

Design and experimental analysis of a cooling system with erythritol/xylitol PCM thermal energy storage

The erythritol/xylitol eutectic phase-change material has strong potential applications in the field of thermal management. In this study, we propose a cooling system for high-power electronic devices that combined a closed water loop and Latent Heat Thermal Energy Storage (LHTES). The LHTES features double helical coil heat exchange tubes, using erythritol/xylitol as the PCM. A test platform was constructed to evaluate heat transfer performance. During the charging phase, the high-power, high-heat flux heater was cooled using a microchannel cold plate. The heat generated by the heater was transferred to the LHTES. In the discharging phase, the heater was turned off, and the heat stored in LHTES was released, achieving the regeneration of the PCM. Based on our previous work, a method involving gas and seeding injection was employed during the discharging process to trigger secondary nucleation. The helical heat exchange coil not only exhibited good heat exchange performance but also provideed sufficient gas pathways, allowing injected bubbles to create ample disturbance. This ensured thorough mixing of seeding particles with supercooled liquid. The total heat storage capacity of the heat storage unit was 10 MJ, achieving a maximum cooling power of 310 W. The impact of different operational parameters was examined, including water flow rate and heating power during the charging process, and the effects of gas and seed crystal injection, cooling fan speed, and water flow rate during the discharging process. An automated control system was established to optimize the cooling system's operation. This study facilitates the practical engineering application of erythritol/xylitol eutectic PCM.

One-dimensional diamond nanostructures: Fabrication, properties and applications

Diamonds exhibit a unique combination of numerous excellent physical and chemical properties, such as the highest hardness, high Young's modulus, wide bandgap, high carrier mobility, negative electron affinity, and high thermal conductivity. Especially, diamond has attracted significant attention in recent years for its outstanding performance in high-frequency and high-power electronic devices and thermal management. Inheriting the intrinsic physical and chemical properties of diamonds, one-dimensional (1D) diamond nanostructures exhibit many additional properties that are unavailable for bulk diamond or thin films, e.g., large specific surface area, ultrahigh elasticity, and some plasticity, tip effect as well as direct transport for photon or photo-induced carriers. These properties make 1D diamond nanostructures an ideal candidate for applications ranging from micro/nano-electromechanical systems (MEMS/NEMS) to field electron emission, optical, electrochemical, and biological areas. This review will first introduce the development of controlled synthesis methods of 1D diamond nanostructure, including bottom-up chemical vapor deposition growth and top-down selective etching of bulk diamond. Subsequently, we will summarize recent advances in the mechanical, electron field emission, optical, and biological properties of 1D diamond nanostructures and their applications in electron and photon emitter, MEMS, sensing, intracellular delivery, etc.

An efficient aluminum gradient mesh wick for enhancing boiling heat transfer performance

With the rapid development of high-power electronic devices, phase change heat transfer has attracted much attention for efficient and lightweight thermal management. However, the mesh structure design for aluminum-based pool boiling enhancement still lacks experimental investigation and theoretical analysis. Herein, an aluminum gradient mesh wick is developed for efficient heat transfer performance. The optimized gradient mesh wick is comprised of a large-hole rhombus flat punching structure on the top and a small-hole 2D screen woven mesh on the bottom, providing sufficient active nucleation density sites, timely liquid supply, and rapid bubble departure. The gradient mesh design for pool boiling enables to achieve a high critical heat flux (CHF) of 1095.46 kW/m2 and a high heat transfer coefficient (HTC) of 46.20 kW/m2·K at a wall superheat of 23.70 °C, which is 167.06% and 240% that of Al plate, respectively. The visualization of bubble behaviors and theoretical analysis reveals that the CHF of the gradient mesh wick mainly depends on the bubble departure and liquid supply, and the bubble departure accounts for a greater proportion. Such aluminum gradient mesh wick provides a strategy for efficient thermal management of lightweight and high-power electronic devices.

A novel Cu@Ag nano paste with low porosity for rapidly sintering in air condition

The emergence of Cu@Ag core-shell nanoparticles presents a promising solution to address issues such as copper oxidation, the high cost of silver, and electro-chemical migration in high-power electronic devices, showcasing their potential for practical applications. In this study, Cu@Ag nanoparticles were synthesized via a liquid-phase reduction method, resulting in an average size of 30 nm. A low-boiling-point mixed organic solvent was meticulously prepared following Raoult's law, enabling the creation of a nano paste utilizing Cu@Ag nanoparticles. This innovation facilitated the sintering of fully dense joints under ambient air conditions, effectively mitigating the oxidation issue caused by silver dewetting behavior in Cu@Ag core-shell nanoparticles. Subsequently, the shear strength and microstructure of the joints were comprehensively studied under various sintering temperatures and durations. Notably, the joint exhibited a shear strength of 17.3 MPa when sintered at 250 °C for 30 min, while achieving full density at a sintering temperature of 300 °C for 30 min. These findings underscore the capacity of Cu@Ag core-shell nano paste to enable the production of high-performance joints under air conditions, utilizing thoughtfully selected organic components.

Comparative Analysis of Sic and Gan: Third-Generation Semiconductor Materials

This article delves into a comprehensive comparative analysis of two prominent third-generation semiconductor materials, silicon carbide (SiC) and gallium nitride (GaN). It explores their foundational theories, practical applications, future prospects, and the hurdles they face in the realm of materials science. SiC is characterized by its impressive thermal conductivity and a wide bandgap, while GaN showcases remarkable electron mobility and high electron saturation velocity. Both materials have demonstrated outstanding capabilities in high-temperature, high-frequency, and high-power electronic devices, finding utility in power conversion, automotive systems, and optoelectronics. Looking forward, SiC and GaN hold tremendous potential in emerging fields such as new energy sources, advanced optoelectronic devices, and semiconductor packaging. Nevertheless, they encounter challenges, including manufacturing costs and the control of crystal defects. In conclusion, these third-generation semiconductors offer extensive possibilities across various domains, although overcoming significant challenges is essential for their widespread integration.

From Wide to Ultrawide-Bandgap Semiconductors for High Power and High Frequency Electronic Devices

Abstract Wide and ultrawide-bandgap (U/WBG) materials have garnered significant attention within the semiconductor device community due to their potential to enhance device performance through their substantial bandgap properties. These exceptional material characteristics can enable more robust and efficient devices, particularly in scenarios involving high power, high frequency, and extreme environmental conditions. Despite the promising outlook, the physics of UWBG materials remains inadequately understood, leading to a notable gap between theoretical predictions and experimental device behavior. To address this knowledge gap and pinpoint areas where further research can have the most significant impact, this review provides an overview of the progress and limitations in U/WBG materials. The review commences by discussing Gallium Nitride, a more mature WBG material that serves as a foundation for establishing fundamental concepts and addressing associated challenges. Subsequently, the focus shifts to the examination of various UWBG materials, including AlGaN/AlN, Diamond, and Ga2O3. For each of these materials, the review delves into their unique properties, growth methods, and current state-of-the-art devices, with a primary emphasis on their applications in power and radio-frequency electronics.

Experimental study on femtosecond laser ablation of 4H–SiC substrate

Silicon carbide (SiC) is an ideal substrate for manufacturing high-power electronic devices and microwave devices and has broad application prospects. The surface treatment of SiC wafers plays a critical role and faces challenges in the semiconductor industry. Among the multiple treatment methods, the laser-based method has gradually attracted the attention of scholars. Therefore, this research uses a femtosecond laser to ablate 4H–SiC sliced wafers and analyzes the influence of key parameters, such as laser pulse energy, defocus amount, repetition frequency, and scanning intervals, on the laser ablation depth, width, and surface morphology. Scanning electron microscopy and laser coherence-focused microscopy were used to characterize the laser ablation surface. When the defocus amount was 6 mm, the microgroove profile formed by the laser was U-shaped. The scanning interval parameters had to be optimized to obtain the optimized surface roughness. The results show that the optimized surface roughness (Sa ) was 0.267 μm, and brittle fracture areas such as microcracks and pits on the original surface were removed. Effective removal facilitates further material surface processing, which provides valuable insights for similar researchers and benefits for the semiconductor industry.

Molecular dynamics study of thermal transport across diamond/cubic boron nitride interfaces

The thermal transport properties at the interface of diamond and cubic boron nitride (c-BN) heterostructures significantly influence heat dissipation in high-power electronic and optoelectronic devices. However, a fundamental understanding of the various parameters modulating the interfacial thermal conductance is still lacking. In this work, we employ non-equilibrium molecular dynamics (NEMD) simulations to systematically investigate the effects of system size, temperature, and defect density on the interfacial thermal conductance across diamond/c-BN interfaces. The results indicate a positive correlation between system length and interface thermal conductance when below the phonon mean free path threshold, attributable to ballistic phonon transport regimes in smaller domains. Additionally, we observe an incremental enhancement in interface thermal conductance with increasing temperature, stemmed from intensified phonon-phonon interactions and reduced boundary scattering of thermal energy carriers. The introduction of vacancy and twinning defects is found to hinder interfacial thermal transport due to heightened phonon scattering processes that impede phononic transmission. The interatomic interactions and lattice dynamics are analyzed to provide insights into the underlying thermal transport physics at the atomistic scale. By tuning the system length from 4 to 16 nm, temperature from 300 to 500 K, and defect density from 0 to 0.4%, we achieve tunable control of the interfacial thermal conductance. Our study elucidates the multiscale mechanisms governing thermal transport across diamond/c-BN and provides potential pathways to actively tailor interfacial thermal properties through structural and temperature engineering. The fundamental understandings are valuable for optimizing heat dissipation and enabling thermal management solutions in next-generation power electronics leveraging these materials.

Diamond deposition on AlN using Q-carbon interlayer through overcoming the substrate limitations

Q-carbon, a quenched form of carbon, is a recently discovered carbon structure that has tremendous properties, compatibility, and potential for use in device fabrication and other electronic and mechanical applications. However, the non-equilibrium nature of the synthesis process and a very small window of growth parameters have limited the formation of Q-carbon to only low thermal conductive substrates. This study aims to overcome these limitations through extensive tuning of the parameters of diamond-like-carbon (DLC), the base structure required for the formation of Q-carbon. The as-deposited DLC films demonstrate ID/IG ratios ranging from 0.12 to 1.67, which are obtained through the optimization of laser energy density, rep rate, and deposition temperature during pulsed laser deposition. Utilizing Simulation of Laser Interaction with Materials, pulsed laser annealing (PLA) was used to directly transform the DLC films into Q-carbon while varying the PLA energy density from 0.3 J/cm2 to 1.2 J/cm2. Findings of Q-carbon formation on sapphire using different DLC films assisted in the preparation of a roadmap for overcoming the substrate limitations for Q-carbon formation. Further, Q-carbon is formed on AlN substrates for the direct deposition of diamond films without the requirement of a non-carbon interfacial layer or nanodiamond seeding layer. The large-area and uniform diamond growth on Q-carbon shows well-faceted and five-fold twinned growth with a 70 % improvement in the residual compressive stress of diamond on AlN. Such a method of diamond deposition on AlN provides the opportunity to address the thermal management issues in wide- and ultra-wide bandgap high-power electronic devices.

Improved flow boiling performance and temperature uniformity in counter-flow interconnected microchannel heat sink

Microchannel flow boiling is one of the most effective solutions to the problem of heat dissipation caused by high power electronic devices. However, inherent drawbacks such as low critical heat flux due to dry-out of the liquid film near the channel exit, relatively high two-phase flow pressure drop, severe temperature nonuniformity and boiling instability at high heat flux still prevent widespread commercial application. In this study, based on the idea of uniform vapor quality along the flow direction, a copper Counter-Flow Interconnected Microchannel (CFIM) was proposed to address the main issues currently faced by two-phase microchannel heat sink. A comprehensive comparative study of CFIM, Co-Current Microchannel (CCM) and Counter-Flow Microchannel (CFM) was carried out from the aspects of boiling stability, boiling heat transfer characteristics and temperature uniformity. Three slots of 0.2 mm, 0.5 mm and 0.8 mm in width, denoted as IM0.2, IM0.5 and IM0.8, respectively, are considered. Experiments are conducted at mass fluxes of 291–618 kg/m2·s, saturation temperature of 40 °C and effective heat fluxes of 3–293 W/cm2, using the dielectric fluid R1233zd(E) as the working fluid. The results show that the CHF and average two-phase heat transfer coefficient (HTC) of CFIM are increased by 40.6 ∼ 100.5 % and 70.4–83.6 %, respectively, while the two-phase pressure drop is decreased by 17–32.6 % compared to CCM. The design of the counter-flow interconnected structure can manipulate the void fraction and two-phase flow pattern, resulting in a near uniform void fraction and flow pattern. The structure of these connecting slots promotes nucleate boiling and fluid mixing of neighboring channels. More importantly, the flow boiling instability and temperature non-uniformity in CFIM are well suppressed. In addition, IM0.2 has higher heat dissipation than IM0.5 and IM0.8 due to enhanced bubble nucleation, reducing superheat requirements and periodic rewetting to the center of the channel. The results of this research reveal that utilizing a microchannel heat sink with a counter-flow interconnected configuration can effectively improve heat transfer performance during flow boiling. Furthermore, it helps to mitigate issues such as flow boiling instability and temperature non-uniformity.