A Double-Layer Parallel MEMS Inductor with Enhanced Current-Carrying Capacity and Thermal Stability

Improving the mechanical property of the silicon aerogel while maintaining its excellent thermal insulation performance is still a big challenge in developing the next-generation thermal insulation materials. To solve this problem, the optically active polyurethane aerogel composite is developed via the sol-gel method to combine the advantages of the thermal insulation performance of the silicon aerogel and the mechanical property of the end-capped siloxane optically-active polyurethane. The prepared composite is characterized by the SEM, the Fourier transform infrared spectroscopy, the absorption-desorption curve, the thermal analysis, and the mechanical property. Results show that the composite has intact pores with high surface area and pore volume, leading to excellent thermal insulation and mechanical performance. Moreover, its thermal insulation performance is greatly enhanced due to the better distributed small pores and the thermal reflective effect of binaphthyl groups which collaboratively block heat loss from thermal conduction and thermal radiation. The thermal stability is similar to silicon aerogel and its heat resistance temperature is 445?. The addition of macromolecular polymers increases the contact points between particles, the contact areas between particles of the network skeletons, and the supporting effect of the skeleton material, which ensures the stability of the material structure. The compressive modulus of prepared composite is up to 2.465 MPa, which is 600 times more than that of the pure SiO2 aerogels.

Adjusting phase change temperature of microcapsules by regulating their core compositions

With the development of SiC technology, the on-resistance of discrete devices drops rapidly and can potentially replace the expensive power modules in high power converters. Unlike parallel discrete devices or a power module with built-in parallel dies, using a single device does not need to slow down the gate driver speed hence can achieve lower switching loss. However, there are still many challenges that need meticulous design considerations. This paper uses the 1200V TO-247-4 package device as an example to provide detailed guidance on device selection, loop optimization, insulation, thermal management, and mounting. A DC-DC converter design example is given with a very low loop inductance and excellent thermal performance. The air-cooled hardware demonstrates the hardware limitation is around 40kW in an 800V to 470V buck operation. Normalized to the R <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">on</inf> of the two devices used, this demonstrates an extremely high power density figure of merit of PDFOM=87kW/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> .

High quantum yields (QY) and stable performances are prerequisites for implementing carbon dots in practical applications. In this study, we demonstrate that nitrogen-doped carbon dots (N-CDs), which were prepared via the hydrothermal treatment of citric acid (CA) and tris(hydroxymethyl)methyl aminomethane (Tris), have a high QY of 75%, together with excellent thermal and photo stability. These N-CDs deliver an excellent thermal stability performance over the temperature range of 25 °C to 95 °C, and even at a heating temperature of 90 °C for 360 min. Upon exposure to UV illumination with a radiant intensity of 20 mW cm-2, 96% fluorescence intensity is retained. This florescence stability performance is probably due to the chemical composition and steric effect of the nitrogen-doping agent. Furthermore, the remarkable optical properties of these N-CDs allow them to be used as invisible ink for loading important information and advanced anti-counterfeiting.

A metal-interlayer-semiconductor (M-I-S) structure with excellent thermal stability and electrical performance for a nonalloyed contact scheme is developed, and considerations for designing thermally stable M-I-S structure are demonstrated on the basis of n-type germanium (Ge). A thermal annealing process makes M-I-S structures lose their Fermi-level unpinning and electron Schottky barrier height reduction effect in two mechanisms: (1) oxygen (O) diffusion from the interlayer to the contact metal due to high reactivity of a pure metal contact with O and (2) interdiffusion between the contact metal and semiconductor through grain boundaries of the interlayer. A pure metal contact such as titanium (Ti) provides very poor thermal stability due to its high reactivity with O. A structure with a tantalum nitride (TaN) metal contact and a titanium dioxide (TiO2) interlayer exhibits moderate thermal stability up to 400 °C because TaN has much lower reactivity with O than with Ti. However, the TiO2 interlayer cannot prevent the interdiffusion process because it is easily crystallized during thermal annealing and its grain boundaries act as diffusion path. A zinc oxide (ZnO) interlayer doped with group-III elements, such as an aluminum-doped ZnO (AZO) interlayer, acts as a good diffusion barrier due to its high crystallization temperature. A TaN/AZO/n-Ge structure provides excellent thermal stability above 500 °C as it can prevent both O diffusion and interdiffusion processes; hence, it exhibits Ohmic contact properties for all thermal annealing temperatures. This work shows that, to fabricate a thermally stable and low resistive M-I-S contact structure, the metal contact should have low reactivity with O and a low work-function, and the interlayer should have a high crystallization temperature and a low conduction band offset to Ge. Furthermore, new insights are provided for designing thermally stable M-I-S contact schemes for any semiconductor material that suffers from the Fermi-level pinning problem.

Electromechanical devices can be used to rapidly modulate light if their mechanical inertias can be made small enough. The usefulness of these devices depends upon the ability to produce them in large arrays with high yield and at low cost, to integrate them with their drive circuitry, and to achieve a high level of reliability and reproducibility. In recent years micromechanical fabrication techniques have been used to produce arrays of miniature optical modula-tors on silicon that can operate at frequencies to 1 MHz with negligible drive power. They are completely compatible with integrated circuit technology and can be fabricated on a silicon wafer along with electronic circuits. In large arrays they can transfer data at a high rate for parallel optical readout of microelectronic devices and sensor arrays. Once in optical form, the data are amenable to optical processing. The development of the micromechanical modulator, its features, performance characteristics and limitations, and its potential applications to data transfer and processing are discussed.

The essential issue in the development of integrated circuit (IC) technologies that allow the arrangement of high densities of electronic components on a single substrate (very‐large‐scale integration technology) is the capability of making a reliable product in a reliable process. To maximize product yield and reliability, modern IC technology requires the availability of a broad range of analytical techniques: on the one hand, techniques that provide fast feed‐back to the process to improve control of the parameters (process monitoring); on the other hand, techniques that allow accruate analysis of failed products (failure analysis). In this contribution the importance of diagnostic techniques for failure analysis will be demonstrated by means of some typical case studies. These include non‐destructive investigations (scanning acoustic tomography) to study the effect of poor adhesion between chip and encapsulant and to study the bonding quality. Furthermore, dendrite‐like structures on the decapsulated chip have been identified with scanning electron microscopy (SEM) and energy dispersive x‐ray analysis (EDXA). In addition, an example will be included that shows the limitations of the performance of the present‐day analytical techniques. The conclusions are: the availability of a large variety of powerful analytical techniques is essential for the development of advanced IC technologies; as a result of the reduction in physical size of the structures on an IC, the limits of performance (in particular, the product of spatial resolution and detection limits) of the present‐day analytical techniques is being approached; there is an increasing need, stimulated by high costs of analysis and required fast feedback of the results, for ‘non‐destructive’ diagnostic techniques.

Programmable circuits are commonly used class of electronic devices. In practice this term usually refers to microcontrollers with different kind of programmable memories and to programmable logic circuits (PAL, CPLD, FPGA). Most of these devices are digital circuits. Thanks to the huge progress in miniaturization of electronic circuits, the new class of devices -programmable analog circuits - was put on the market. These circuits bring new possibilities to design electronic circuit. One of the most promising fields of application is construction of analog signal conditioning circuits. This paper describes feature and parameters of sample programmable analog circuits. It depicts internal structure and theory of operation of these devices. One of commercially available programmable analog circuits was used in development of signal conditioning block for vibration measurement system. It works as programmable gain amplifier and low-pass anti-aliasing filter with programmable cut-off frequency. Amplifier transient characteristics for different gain values and frequency response of the filter were measured

Study on the photothermal conversion enhancement performance and application of the metal-polyphenol phase-change microcapsules modified by molybdenum disulfide

The practical application of phase-change materials (PCMs) is limited due to leakage and low thermal conductivity. In this study, waste poplar sawdust (PW) and its derived biochar (PWC) were used as encapsulation materials, with stearic acid (SA) as the phase-change material, to successfully prepare composite phase-change materials with no leakage and high thermal conductivity. The microstructure and pore structure of PW and PWC were studied through SEM and nitrogen adsorption–desorption curves. The analysis results of FTIR, XRD and TGA indicated SA/PW and SA/PWC had excellent chemical compatibility and thermal stability. Excitingly, compared to SA/PW, SA/PWC exhibited higher latent heat and thermal conductivity. DSC results showed that the phase-change latent heat of SA/PWC can reach 100 J/g, which was 21% higher than that of SA/PW and the thermal conductivity increased by 87% times compared to SA/PW . In addition, SA/PW and SA/PWC still exhibited good thermal energy storage capacity after 200 thermal cycles. This research not only effectively resolved the leakage and low thermal conductivity challenges associated with PCMs but also introduced a novel utilization strategy for waste poplar sawdust, thereby significantly expanding its application potential.

Thin films, ranging in thickness from a few nanometers to several micrometers, play a key role in the development of high-voltage and power electronics technologies. Using precise deposition techniques, these ultra-thin layers provide essential properties such as insulation, thermal management, and improved electrical performance. Using thin films, device miniaturization and performance have been significantly improved, allowing them to be integrated into advanced applications such as capacitors, resistors, and transistors. Their role is particularly evident in wide-bandgap semiconductor devices such as silicon carbide (SiC) and gallium nitride (GaN), which have excellent switching speed, breakdown voltage, and thermal performance. This chapter highlights the importance of advanced deposition methods, including atomic layer deposition (ALD) and chemical vapor deposition (CVD), which ensure precise control of film thickness and structure. These technologies produce application-specific, defect-free layers, which are critical for maintaining the reliability and performance of high-voltage systems. Additionally, a variety of materials used in the films, such as high-k dielectrics and nanocomposites, facilitate the development of high capacitance density capacitors and high-performance resistors. Their use in real-world scenarios such as electric vehicles and renewable energy systems has advanced power electronics technology, improving energy conversion, thermal stability, and overall efficiency. Going forward, the integration of new materials and emerging technologies is expected to further enhance the performance of the films. Research into two-dimensional materials such as graphene and transition metal dichalcogenides, as well as nanostructured films embedded with quantum dots and nanowires, offers the potential for next-generation energy storage and conversion devices. Furthermore, flexible and stretchable films open the way to wearable electronics and medical devices. By solving challenges such as thermal management and scalability, thin films have the potential to revolutionize power electronics, driving innovation in applications ranging from smart grids to advanced aerospace systems.

Bio-based sodium alginate/ammonium polyphosphate aerogel-coated rigid polyurethane foam: A sustainable approach for enhanced flame retardancy.

Design and fabrication of reversible thermochromic microencapsulated phase change materials for thermal energy storage and its antibacterial activity

Homogeneous organic–inorganic hybrid materials with excellent thermal and optical performance were successfully prepared via the mixing of (3‐methacryloxypropyl)trimethoxysilane‐capped acrylic resin with titania synthesized by sol–gel approaches. The effects of the titania content, amount of water, and pH in the sol–gel and the ratio of the solvents (butyl acetate and ethanol) on the structures and properties of the hybrid materials were studied. More titania, more water, and base catalysis in the sol–gel process and a higher ratio of butyl acetate to ethanol for the hybrids led to a larger size and a more compact structure of the titania phase. Increasing the titania content dramatically improved the glass‐transition temperature, UV‐shielding properties, and refractive index for the hybrid materials, and it did not reduce their optical transparency. In general, better thermal stability and optical properties were achieved for the hybrid materials prepared with less water, lower pH values (e.g., acidic or neutral conditions), and a lower ratio of butyl acetate to ethanol. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 637–649, 2005

Using surface-modified UiO-66 with hierarchical pores to pack polyethylene glycol for phase change thermal energy storage: Experiment and molecular dynamics simulations