Review on thermal energy storage with phase change: materials, heat transfer analysis and applications

Light-Emitting Diodes. (Monographs in Electrical and Electronic Engineering.) By A. A. Bergh and P. J. Dean. Pp. viii+591. (Clarendon: Oxford; Oxford University: London, 1976.) £22.

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Light-emitting diodes

Gallium oxide (Ga2O3) is emerging as a viable candidate for certain classes of power electronics, solar blind UV photodetectors, solar cells, and sensors with capabilities beyond existing technologies due to its large bandgap. It is usually reported that there are five different polymorphs of Ga2O3, namely, the monoclinic (β-Ga2O3), rhombohedral (α), defective spinel (γ), cubic (δ), or orthorhombic (e) structures. Of these, the β-polymorph is the stable form under normal conditions and has been the most widely studied and utilized. Since melt growth techniques can be used to grow bulk crystals of β-GaO3, the cost of producing larger area, uniform substrates is potentially lower compared to the vapor growth techniques used to manufacture bulk crystals of GaN and SiC. The performance of technologically important high voltage rectifiers and enhancement-mode Metal-Oxide Field Effect Transistors benefit from the larger critical electric field of β-Ga2O3 relative to either SiC or GaN. However, the absence of clear demonstrations of p-type doping in Ga2O3, which may be a fundamental issue resulting from the band structure, makes it very difficult to simultaneously achieve low turn-on voltages and ultra-high breakdown. The purpose of this review is to summarize recent advances in the growth, processing, and device performance of the most widely studied polymorph, β-Ga2O3. The role of defects and impurities on the transport and optical properties of bulk, epitaxial, and nanostructures material, the difficulty in p-type doping, and the development of processing techniques like etching, contact formation, dielectrics for gate formation, and passivation are discussed. Areas where continued development is needed to fully exploit the properties of Ga2O3 are identified.

A review of Ga2O3 materials, processing, and devices

International Technology Roadmap for Semiconductors 2003の要求清浄度について － シリコンウエハ表面と雰囲気環境に要求される清浄度, 分析方法の現状について －

Small, light weight and multifunctional electronic components are attracting much attention because of the rapid growth of the wireless communication systems and microwave products in the consumer electronic market. The component manufacturers are thus forced to search for new advanced integration, packaging and interconnection technologies. One solution is the low temperature cofired ceramic (LTCC) technology enabling fabrication of three-dimensional ceramic modules with low dielectric loss and embedded silver electrodes. During the past 15 years, a large number of new dielectric LTCCs for high frequency applications have been developed. About 1000 papers were published and ∼500 patents were filed in the area of LTCC and related technologies. However, the data of these several very useful materials are scattered. The main purpose of this review is to bring the data and science of these materials together, which will be of immense help to researchers and technologists all over the world. The comme...

Low loss dielectric materials for LTCC applications: a review

The present work considers the compact modeling of unshrouded parallel plate heat sinks in laminar forced convection. The computational domain includes three heat sinks in series, cooled by an intake fan. The two upstream heat sinks are represented as “porous blocks”, each with an effective thermal conductivity and a pressure loss coefficient, while the downstream heat sink, assumed to be the component requiring the most accurate characterization, is modeled in detail. A large parametric space covering three typical heat sink geometries, as well as a range of common inlet velocities, separation distances between the heat sinks, and bypass clearances is considered in the development and evaluation of the compact models. The current study uses a boundary layer-based methodology, accounting for both the viscous dissipation and form drag losses, to determine the pressure drop characteristics, and an effective conductivity methodology, using a flow bypass model and Nusselt number correlation, to determine the effective thermal conductivity, for the porous block representation of the heat sink. The results indicate that the introduction of compact heat sinks has little influence on the pressure drop of the critical heat sink. Good agreement in pressure drops, typically in the range of 5%, is also obtained between “detailed” heat sink models and their corresponding porous block representation. The introduction of the compact models is found to have little influence (typically less than 1°C) on the base temperature of the critical heat sinks. For the compact heat sinks, the agreement is again within a typical difference of 5% in thermal resistance. Dramatic improvements were observed in the mesh count (factor > 10X) and solution time (factor >20X) required to achieve a high-fidelity simulation of the velocity, pressure, and temperature fields.Copyright © 2003 by ASME

Compact Modeling of Unshrouded Plate Fin Heat Sinks

IR Thermography of Two-Phase Microgap Cooler

Thermal Performance Mapping of Direct Liquid Cooled 3d Chip Stacks

Thermofluid/electrical co-design of emerging electronic components − challenges and opportunities

A finite element analysis (FEA) approach is developed and used to efficiently evaluate and optimize the boiling performance of longitudinal rectangular plate fin heat sinks, including the explicit dependence of fin spacing on boiling heat transfer coefficients and CHF. Polished silicon heat sinks are shown to dissipate nearly five times the CHF limit of the unfinned base area and outperform comparable aluminum heat sinks by a factor of two. For optimum heat sink geometries, over the parameter ranges explored, fin thickness is found to be approximately equal to the fin spacing, and the relationship between optimum thickness and spacing is demonstrated to be relatively insensitive to fin thermal conductivity. Results suggest that even greater performance enhancements may be gained with appropriately-selected advanced materials.Copyright © 2007 by ASME

Avram Bar-Cohen

Papers

Compact Modeling of Unshrouded Plate Fin Heat Sinks

IR Thermography of Two-Phase Microgap Cooler

Thermal Performance Mapping of Direct Liquid Cooled 3d Chip Stacks

Thermofluid/electrical co-design of emerging electronic components − challenges and opportunities

Optimization of Pool Boiling Heat Sinks Including the Effects of Confinement in the Interfin Spaces