Journal articles: 'Conductive thermal diode'

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Kasali, Suraju Olawale, Jose Ordonez-Miranda, Kamal Alaili, and Karl Joulain. "Spherical and cylindrical conductive thermal diodes based on two phase-change materials." Zeitschrift für Naturforschung A 77, no. 2 (October 22, 2021): 181–90. http://dx.doi.org/10.1515/zna-2021-0170.

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Abstract We theoretically studied and optimized the thermal rectification of spherical and cylindrical conductive thermal diodes operating with two phase-change materials (PCMs), whose thermal conductivities significantly changes in a narrow interval of temperatures. This is done by deriving simple analytical expressions for the heat flows, temperature profiles and rectification factors of both diodes. It is shown that diode geometry has a significant impact on the heat flows and temperature profiles, but not so much on the thermal diode rectification factor. Optimal rectification factors of 63.5 and 63.2% are obtained for the spherical and cylindrical thermal diodes operating between the terminals of VO2 and polyethylene with a temperature difference of 150 K spanning the metal–insulator transition of both PCMs. These similar rectification factors could be enhanced even more with a phase-change material exhibiting higher contrast thermal conductivity than the ones in the present study. The obtained results can thus be useful to guide the development of PCMs capable of optimizing the rectification of conductive heat flows with different geometries.

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Kasali, Suraju Olawale, Jose Ordonez-Miranda, and Karl Joulain. "Conductive thermal diode based on two phase-change materials." International Journal of Thermal Sciences 153 (July 2020): 106393. http://dx.doi.org/10.1016/j.ijthermalsci.2020.106393.

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Lee, Dong Kyu, Yu-Jung Cha, and Joon Seop Kwak. "Effect of Thermal Interface Materials on Heat Dissipation of Light-Emitting Diode Headlamps with Thermally-Conductive Plastics." Journal of Nanoscience and Nanotechnology 21, no. 7 (July 1, 2021): 3721–28. http://dx.doi.org/10.1166/jnn.2021.19218.

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We study the effect of thermal interface material such as thermal-conductive plastic on the dissipation of generated heat from the light-emitting diodes (LEDs) based headlamp for the application of environment-friendly green energy in vehicles. The thermal distribution and the performances of thermal-conductive plastic with heatsink are consistently investigated by using experimental and numerical results. Various thicknesses of thermal-conductive plastics from 0.3 mm to 1.0 mm used in this research work. Basically the thermal-conductive plastic reduces the thermal interface resistance between the contact of two solid surfaces. As a result, High electrical power of about 15 W (1 A and 15 V) can be possible for applying to the high-power LED package without any damage. The soldering temperature of LED package without thermal-conductive plastic shows approximately 138.7 °C which is higher compared to the LED package with thermal-conductive plastic (124.3 °C). On the other hand, the soldering temperature increases from 124.3 to 127.6 °C with increasing the thicknesses of thermal-conductive plastic. In addition, the soldering temperature decreases from 138.7 to 124.3 °C with increasing the thermal conductivities of thermal-conductive plastic. Finally, a highly thermal conductive property of thermal-conductive plastic will propose for optimum dissipation of generated heat from the LEDs-based headlamp. We also successfully estimate the junction temperature of packaged LEDs by using soldering temperature.

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Ordonez-Miranda, Jose, James M. Hill, Karl Joulain, Younès Ezzahri, and Jérémie Drevillon. "Conductive thermal diode based on the thermal hysteresis of VO2 and nitinol." Journal of Applied Physics 123, no. 8 (February 28, 2018): 085102. http://dx.doi.org/10.1063/1.5019854.

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Mou, Yun, Jiaxin Liu, Qing Wang, Zhenyu Lei, Yang Peng, and Mingxiang Chen. "A novel thermal conductive Ag2O paste for thermal management of light-emitting diode." Materials Letters 316 (June 2022): 132022. http://dx.doi.org/10.1016/j.matlet.2022.132022.

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Alander, Tapani M., Pekka A. Heino, and Eero O. Ristolainen. "Analysis of Substrates for Single Emitter Laser Diodes." Journal of Electronic Packaging 125, no. 3 (September 1, 2003): 313–18. http://dx.doi.org/10.1115/1.1527657.

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Electrically conductive substrates (i.e., metals) are often used in the mounting of semiconductor laser diodes. While metals offer a good electrical and thermal performance, they restrict the system integration due to lack of signal routing capability. Since the implementations utilizing laser diodes have become more common, the integration level has also become an important factor in these products. Mounting of lasers on insulative substrates is the key to large-scale integration. Organic boards form the de facto standard of insulative substrates; however, their use with lasers is impossible due to low thermal conductivity. Ceramics, however, offer nearly the same thermal performance as metals but as electrically insulative materials also provide the foundation for high integration levels. In this study the effects of three different ceramic substrates on the stresses within diode lasers was evaluated. Finite element method was used to calculate the mounting induced straining and the thermal performance of the substrate. The same procedure was employed to examine the optimum metallization thickness for the ceramic substrates. The results present how greatly the substrate material can affect the very delicate laser diode. The ceramic substrates, though having nearly the same properties, exhibited clearly distinctive behavior and a great difference in thermal and mechanical performance.

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Ali, Zulfiqar, Yuan Gao, Bo Tang, Xinfeng Wu, Ying Wang, Maohua Li, Xiao Hou, Linhong Li, Nan Jiang, and Jinhong Yu. "Preparation, Properties and Mechanisms of Carbon Fiber/Polymer Composites for Thermal Management Applications." Polymers 13, no. 1 (January 5, 2021): 169. http://dx.doi.org/10.3390/polym13010169.

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With the increasing integration and miniaturization of electronic devices, heat dissipation has become a major challenge. The traditional printed polymer circuit board can no longer meet the heat dissipation demands of microelectronic equipment. If the heat cannot be removed quickly and effectively, the efficiency of the devices will be decreased and their lifetime will be shortened. In addition, the development of the aerospace, automobiles, light emitting diode (LED{ TA \1 “LED; lightemitting diode” \s “LED” \c 1 }) and energy harvesting and conversion has gradually increased the demand for low-density and high thermal conductive materials. In recent years, carbon fiber (CF{ TA \1 “CF; carbon fiber” \c 1 }) has been widely used for the preparation of polymer composites due to its good mechanical property and ultra-high thermal conductivity. CF materials easily form thermal conduction paths through polymer composites to improve the thermal conductivity. This paper describes the research progress, thermal conductivity mechanisms, preparation methods, factors influencing thermal conductivity and provides relevant suggestions for the development of CF composites for thermal management.

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Zhou, Jieyang, Zhe Wang, and Yun Wang. "Experimental Measurement of Thermal Conductivities in a Thin Heterogeneous Structure of Thermal Diodes." E3S Web of Conferences 194 (2020): 01019. http://dx.doi.org/10.1051/e3sconf/202019401019.

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Thermal diode has a wide application in the field of thermal management and thermal control. This article reports experimental results about measurement of the thermal conductivities of a novel thin layer (the thickness is about 0.3mm) for thermal diode applications. The layer consists printing paper, nylon mesh and liquid water, which are sealed between two pieces of aluminum, thus has a heterogeneity sublayers structure. It is shown that the thermal conductances are different in the two opposite through-plane directions. At 75 ˚C, the thermal conductivity is 0.457 W/mK in the conductive direction, more than 3 times larger than that in the opposite direction (0.133 W/mK). This phenomenon is due to the one-direction flow of working fluid. The thermal performance is dependent on the operating temperature and liquid water content in the structure.

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Huang, Yao, Semen Kormakov, Xiaoxiang He, Xiaolong Gao, Xiuting Zheng, Ying Liu, Jingyao Sun, and Daming Wu. "Conductive Polymer Composites from Renewable Resources: An Overview of Preparation, Properties, and Applications." Polymers 11, no. 2 (January 22, 2019): 187. http://dx.doi.org/10.3390/polym11020187.

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This article reviews recent advances in conductive polymer composites from renewable resources, and introduces a number of potential applications for this material class. In order to overcome disadvantages such as poor mechanical properties of polymers from renewable resources, and give renewable polymer composites better electrical and thermal conductive properties, various filling contents and matrix polymers have been developed over the last decade. These natural or reusable filling contents, polymers, and their composites are expected to greatly reduce the tremendous pressure of industrial development on the natural environment while offering acceptable conductive properties. The unique characteristics, such as electrical/thermal conductivity, mechanical strength, biodegradability and recyclability of renewable conductive polymer composites has enabled them to be implemented in many novel and exciting applications including chemical sensors, light-emitting diode, batteries, fuel cells, heat exchangers, biosensors etc. In this article, the progress of conductive composites from natural or reusable filling contents and polymer matrices, including (1) natural polymers, such as starch and cellulose, (2) conductive filler, and (3) preparation approaches, are described, with an emphasis on potential applications of these bio-based conductive polymer composites. Moreover, several commonly-used and innovative methods for the preparation of conductive polymer composites are also introduced and compared systematically.

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SOZONOV, Maxim V., Alexander N. BUSYGIN, Andrey N. BOBYLEV, and Anatolii A. KISLITSYN. "THERMOPHYSICAL MODEL OF A MEMRISTOR-DIODE MICROCHIP." Tyumen State University Herald. Physical and Mathematical Modeling. Oil, Gas, Energy 7, no. 4 (2021): 62–78. http://dx.doi.org/10.21684/2411-7978-2021-7-4-62-78.

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The most popular models of memristor, based on the principle of formation and breakage of conductive filaments in memristive layer, are applied to consideration of a single memristor. However, consideration of a full-fledged microchip with many memristors may be also interesting. In this case, it is very important to determine the thermal mode of work of the device, in particular, to determine if it needs cooling and how the microchip architecture affects on the nature of heat transfer. At the same time, the proposed model should be quite simple, since modeling of conductive filaments in each memristor greatly complicates work with the model and requires large computational resources. In this paper a thermophysical model of the microchip based on a memristor-diode crossbar created at the REC “Nanotechnology” at Tyumen State University is presented. The model takes into account Joule heating and convective heat transfer. A feature of the model is a simplified determination of memristor state by the resistivity value of memristive layer from the data of the current-voltage characteristic of a real memristor sample. Simulation is carried out in the ANSYS software package. Within the framework of the model, self-consistent electrical and thermophysical problems are solved in a non-stationary setting. The temperature fields and graphs of the temperature versus time were obtained for various operating modes. The results obtained are in good agreement with similar data from other studies published in the literature. The model shows itself well in various operating modes, both in modes with memristor state switching process and without it. The presented model can be used at the design stage to take into account the features of the microchip architecture, which can significantly affect the thermal state of microchip operating modes.

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Micheli, Leonardo, Nabin Sarmah, K. S. Reddy, Xichun Luo, and Tapas K. Mallick. "Design, Development, and Analysis of a Densely Packed 500x Concentrating Photovoltaic Cell Assembly on Insulated Metal Substrate." International Journal of Photoenergy 2015 (2015): 1–18. http://dx.doi.org/10.1155/2015/341032.

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The paper presents a novel densely packed assembly for high concentrating photovoltaic applications, designed to fit 125x primary and 4x secondary reflective optics. This assembly can accommodate 144 multijunction cells and is one of the most populated modules presented so far. Based on the thermal simulation results, an aluminum-based insulated metal substrate has been used as baseplate; this technology is commonly exploited for Light Emitting Diode applications, due to its optimal thermal management. The original outline of the conductive copper layer has been developed to minimize Joule losses by reducing the number of interconnections among the cells in series. Oversized Schottky diodes have been employed for bypassing purposes. The whole design fits the IPC-2221 requirements. The plate has been manufactured using standard electronic processes and then characterized through an indoor test and the results are here presented and commented on. The assembly achieves a fill factor above 80% and an efficiency of 29.4% at 500x, less than 2% lower than that of a single cell commercial receiver. The novel design of the conductive pattern is conceived to decrease the power losses and the deployment of an insulated metal substrate represents an improvement towards the awaited cost-cutting for high concentrating photovoltaic technologies.

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Das, A., S. Mitra, P. Agarwal, and A. Sengupta. "Prolonged intra-operative thermal exposure in endoscopic ear surgery: is it really safe?" Journal of Laryngology & Otology 134, no. 8 (August 2020): 727–31. http://dx.doi.org/10.1017/s0022215120001449.

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AbstractObjectiveThe aim of this study was to assess change in temperature, audiometric outcomes and post-operative complications following exposure to different light sources during endoscopic ear surgery.MethodA total of 64 patients diagnosed with chronic otitis media with central perforation and pure conductive hearing loss underwent endoscopic type 1 tympanoplasty. The patients were randomised into two groups based on the light source used: xenon or light-emitting diode. Temperature was measured using a K type thermocouple at the promontory and round window niche. Mean temperature change with respect to operating time, mean audiometric change, incidence of vomiting in the first 24 hours, vertigo and tinnitus at the end of the first week were observed.ResultsMean temperature change showed a statistically significant difference with increasing length of operating time with the xenon light source and when the two light sources were compared for a particular time interval. Mean audiometric change showed statistically significant deterioration at higher frequencies (4, 6 and 8 kHz) with the xenon light source but only at 8 kHz for the light emitting diode source. When the mean audiometric change was compared between light sources for a particular frequency, statistical significance was found at 4, 6 and 8 kHz. Post-operative complications were vomiting, vertigo and tinnitus (p-values of 0.042, 0.099 and 0.147, respectively, between two groups).ConclusionLight emitting diodes are associated with less significant middle-ear temperature rises and audiometric changes at higher frequencies when compared to xenon light sources. Hence, xenon should be replaced with cooler light sources.

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Yu, Kangkang, Tao Yuan, Songdi Zhang, and Chenlu Bao. "Hypergravity-Induced Accumulation: A New, Efficient, and Simple Strategy to Improve the Thermal Conductivity of Boron Nitride Filled Polymer Composites." Polymers 13, no. 3 (January 31, 2021): 459. http://dx.doi.org/10.3390/polym13030459.

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Thermal conductive polymer composites (filled type) consisting of thermal conductive fillers and a polymer matrix have been widely used in a range of areas. More than 10 strategies have been developed to improve the thermal conductivity of polymer composites. Here we report a new “hypergravity accumulation” strategy. Raw material mixtures of boron nitride/silicone rubber composites were treated in hypergravity fields (800–20,000 g, relative gravity acceleration) before heat-curing. A series of comparison studies were made. It was found that hypergravity treatments could efficiently improve the microstructures and thermal conductivity of the composites. When the hypergravity was about 20,000 g (relative gravity acceleration), the obtained spherical boron nitride/silicone rubber composites had highly compacted microstructures and high and isotropic thermal conductivity. The highest thermal conductivity reached 4.0 W/mK. Thermal interface application study showed that the composites could help to decrease the temperature on a light-emitting diode (LED) chip by 5 °C. The mechanism of the improved microstructure increased thermal conductivity, and the high viscosity problem in the preparation of boron nitride/silicone rubber composites, and the advantages and disadvantages of the hypergravity accumulation strategy, were discussed. Overall, this work has provided a new, efficient, and simple strategy to improve the thermal conductivity of boron nitride/silicone rubber and other polymer composites (filled type).

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Lee, Jonghwan, and Ki-Youn Kwon. "Thermal Stress Analysis for High CRI LED Indoor Lighting Module." Journal of Microelectronics and Electronic Packaging 15, no. 3 (July 1, 2018): 126–31. http://dx.doi.org/10.4071/imaps.655549.

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Abstract This research is for developing a new light emitting diode (LED) indoor lighting module with high color rendering index greater than 95. When the LED is operated, electrical energy is generated and heat is released. The failing of heat dispersal degrades the performance and decreases the operating life. To manage the thermal problem effectively, several approaches have been tested in this research study. A heat sink is designed to absorb and transfer heat from the LED module. To analyze the heat flow and thermal stress of the designed LED products effectively, hexahedral mesh generation has been implemented. Heat transfer analysis was performed to find an optimal conductive material. The outcomes of this research study suggest the best material for LED products and show the result of thermal transfer simulation.

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Lee, Dong Kyu, Jae Min Lee, Moon Uk Cho, Hyun Jung Park, Yu-Jung Cha, Hyeong Jin Kim, and Joon Seop Kwak. "Influence of the Thermal Conductivity of Thermally Conductive Plastics on the Thermal Distribution of an Light-Emitting Diode Headlight for Vehicles." Journal of Nanoscience and Nanotechnology 18, no. 9 (September 1, 2018): 5904–7. http://dx.doi.org/10.1166/jnn.2018.15587.

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Chen, Yenlung, Juikun Chang, Chun Huang, Changche Chiu, Wei Lai, Zhiting Ye, and Pin Han. "Development of Radiator with Thermoplastic Polymer and Insert-Molded Aluminum Alloy Parts for Light-Emitting Diode Headlights." Applied Sciences 12, no. 11 (May 26, 2022): 5385. http://dx.doi.org/10.3390/app12115385.

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The increasing popularity of electric vehicles has increased the demand for lightweight auto parts. However, the excessive weight of traditional metal heat sinks has remained a concern. Metal has excellent thermal conductivity but low radiation efficiency. Conversely, thermoplastic polymers have excellent heat radiation efficiency but poor thermal conductivity. In this study, we propose a radiator constructed using thermoplastic polymer and insert-molded aluminum alloy parts to maintain the low junction temperature of light-emitting diodes (LEDs); the radiator’s weight is reduced through a combination of aluminum alloy and a thermally conductive polymer designed for automotive headlights. At an LED thermal load of 11.48 W, the measured temperature on the LED pad is 60.8 °C. The weight of the proposed radiator is 23.37% lighter than that of a pure metal radiator. When the lightweight radiator is used in high-power LED headlights, it effectively dissipates heat within a limited space.

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Chiang, Yen-Chih, Bing-Cheng Lin, Kuo-Ju Chen, Sheng-Huan Chiu, Chien-Chung Lin, Po-Tsung Lee, Min-Hsiung Shih, and Hao-Chung Kuo. "Efficiency and Droop Improvement in GaN-Based High-Voltage Flip Chip LEDs." International Journal of Photoenergy 2014 (2014): 1–7. http://dx.doi.org/10.1155/2014/385257.

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The GaN-based high-voltage flip chip light-emitting diode (HVFC-LED) is designed and developed for the purpose of efficiency enhancement. In our design, the distributed Bragg reflector (DBR) is deposited at the bonded substrate to increase the light extraction. After the flip chip process, the general current-voltage characteristics between the flip chip sample and the traditional sample are essentially the same. With the help of great thermal conductive silicon substrate and the bottom DBR, the HVFC-LED is able to enhance the power by 37.1% when compared to the traditional high-voltage LEDs. The wall-plug efficiencies of the HVFC-LED also show good droop reduction as high as 9.9% compared to the traditional devices.

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Ruffino, F., A. Canino, M. G. Grimaldi, F. Giannazzo, F. Roccaforte, and V. Raineri. "Electrical Properties of Self-Assembled Nano-Schottky Diodes." Journal of Nanomaterials 2008 (2008): 1–7. http://dx.doi.org/10.1155/2008/243792.

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A bottom-up methodology to fabricate a nanostructured material by Au nanoclusters on 6H-SiC surface is illustrated. Furthermore, a methodology to control its structural properties by thermal-induced self-organization of the Au nanoclusters is demonstrated. To this aim, the self-organization kinetic mechanisms of Au nanoclusters on SiC surface were experimentally studied by scanning electron microscopy, atomic force microscopy, Rutherford backscattering spectrometry and theoretically modelled by a ripening process. The fabricated nanostructured materials were used to probe, by local conductive atomic force microscopy analyses, the electrical properties of nano-Schottky contact Au nanocluster/SiC. Strong efforts were dedicated to correlate the structural and electrical characteristics: the main observation was the Schottky barrier height dependence of the nano-Schottky contact on the cluster size. Such behavior was interpreted considering the physics of few electron quantum dots merged with the concepts of ballistic transport and thermoionic emission finding a satisfying agreement between the theoretical prediction and the experimental data. The fabricated Au nanocluster/SiC nanocontact is suggested as a prototype of nano-Schottky diode integrable in complex nanoelectronic circuits.

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Liu, Yang, Fenglian Sun, Cadmus A. Yuan, and Guoqi Zhang. "Thermal analysis of chip-on-flexible LED packages with Cu heat sinks by SnBi soldering." Microelectronics International 33, no. 1 (January 4, 2016): 42–46. http://dx.doi.org/10.1108/mi-04-2015-0034.

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Purpose – The purpose of this paper is to discuss the possibility of using soldering process for the bonding of chip-on-flexible (COF) light-emitting diode (LED) packages to heat sinks. The common bonding materials are thermal conductive adhesives. For thermal performance and reliability concerns, Tin-Bismuth (SnBi) lead-free solder paste was used for the connection of the COF packages and the Cu heat sinks by a soldering process in this study. Meanwhile, the geometrical effect of the SnBi solder layer on the thermal performance was also investigated. Design/methodology/approach – The effects of the bonding materials and the area of the solder layers on the thermal performance of the LED modules were investigated by finite element simulation and experimental tests. Findings – The SnBi soldered modules show much lower thermal resistance at the bonding layers than the adhesive-bonded LED module. Vertical heat transfer from the LED chips to the heat sinks is the primary heat dissipation mode for the SnBi soldered modules. Thus, the LED module with local solder layer shows similar LED thermal performance with the full-area soldered module. Meanwhile, the local soldering process decreases the possibility to form randomly distributed defects such as the large area voids and residue flux in the solder layers. Research limitations/implications – The research is still in progress. Further studies mainly focus on the reliability of the samples with different bonding materials. Practical implications – COF package is a new structure for LED packages. This study provides a comparison between SnBi solder and adhesive material on the thermal performance of the LED. Meanwhile, the authors optimized the geometrical design for the solder layer. The study provides a feasible bonding process for COF packages onto heat sinks. Originality/value – This study provides a soldering process for the COF LED packages. The thermal performance of the LED light source was improved significantly by the new process.

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Dohle, Rainer, Gerold Henning, Maximilian Wallrodt, Christoph Gréus, and Christian Neumeyr. "Advanced Packaging Technology for Novel 1-dimensional and 2-dimensional VCSEL Arrays." International Symposium on Microelectronics 2021, no. 1 (October 1, 2021): 000265–70. http://dx.doi.org/10.4071/1085-8024-2021.1.000265.

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Abstract In this paper we present an optimized manufacturing technique for special long-wavelength 1-dimensional and 2-dimensional Vertical Cavity Surface Emitting Laser Diode (VCSEL) arrays with focus on die bonding and a special wire bonding process as well as additional possibilities to make the manufacturing more productive and to increase the product quality, reliability, and life time. VCSEL arrays have a very broad application potential. Objective of this paper is the development of an assembly technology for long-wavelength VCSEL arrays with high positioning accuracy for automated production with high total yield, using gold-based conductive glue (because silver migration is a concern) securing high yield and extremely high reliability and lifetime. Due to special customer requirements, a final thickness of the conductive glue of 35 micron with low standard deviation is necessary. For highest reliability, gold wire bonding of the top side contact of the VCSEL to a silicon substrate with gold metallization has been a customer requirement. With the described technique we develop and produce customer specific products with dedicated wavelength, performance, and packaging options. Bases on our findings, very flexible and scalable solutions are possible, matching many different applications. Finally, we will present an overview of our results on the physical and electro-optical characterization of the VCSEL devices. This yielded a very productive manufacturing technique, meeting the requirements mentioned above. Special design features of the VCSEL ensure that the relatively high thermal resistance of the cured conductive glue layer does not impair the electro-optical properties or the lifetime of the VCSELs. For the interconnection of the top side contact we used gold wire with 20 microns diameter, using ball-wedge, Stand-Off Stich Bond process with special loop geometry, required by the customer. Due to the properties of the semiconductor material of the VCSELs a low bonding temperature is required, enabled by our special wire bonding process. Gold wire bonding delivered excellent results, by far exceeding the customer specification. The optical spectrum of the VCSELs and other measurements indicate that the assembly processes do not harm the laser diodes or their electro-optical properties. All customer requirements for the 1-dimensional and 2-dimensional VCSEL arrays have been met. The electro-optical and burn-in data furnished proof of the quality of the engineered assembly technology. The technologies developed for low current as well as high current laser arrays will enable new devices for a huge amount of new applications because of the novel manufacturing processes as well as innovative packaging of the VCSEL arrays.

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Choi, Younggon, Hong-Seok Kim, Haunmin Lee, Wonjoon Choi, Sang Jik Kwon, Jae-Hee Han, and Eou-Sik Cho. "Effects of Insertion of Ag Mid-Layers on Laser Direct Ablation of Transparent Conductive ITO/Ag/ITO Multilayers: Role of Effective Absorption and Focusing of Photothermal Energy." Materials 14, no. 18 (September 7, 2021): 5136. http://dx.doi.org/10.3390/ma14185136.

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From the viewpoint of the device performance, the fabrication and patterning of oxide–metal–oxide (OMO) multilayers (MLs) as transparent conductive oxide electrodes with a high figure of merit have been extensively investigated for diverse optoelectronic and energy device applications, although the issues of their general concerns about possible shortcomings, such as a more complicated fabrication process with increasing cost, still remain. However, the underlying mechanism by which a thin metal mid-layer affects the overall performance of prepatterned OMO ML electrodes has not been fully elucidated. In this study, indium tin oxide (ITO)/silver (Ag)/ITO MLs are fabricated using an in-line sputtering method for different Ag thicknesses on glass substrates. Subsequently, a Q-switched diode-pumped neodymium-doped yttrium vanadate (Nd:YVO4, λ = 1064 nm) laser is employed for the direct ablation of the ITO/Ag/ITO ML films to pattern ITO/Ag/ITO ML electrodes. Analysis of the laser-patterned results indicate that the ITO/Ag/ITO ML films exhibit wider ablation widths and lower ablation thresholds than ITO single layer (SL) films. However, the dependence of Ag thickness on the laser patterning results of the ITO/Ag/ITO MLs is not observed, despite the difference in their absorption coefficients. The results show that the laser direct patterning of ITO/Ag/ITO MLs is primarily affected by rapid thermal heating, melting, and vaporization of the inserted Ag mid-layer, which has considerably higher thermal conductivity and absorption coefficients than the ITO layers. Simulation reveals the importance of the Ag mid-layer in the effective absorption and focusing of photothermal energy, thereby supporting the experimental observations. The laser-patterned ITO/Ag/ITO ML electrodes indicate a comparable optical transmittance, a higher electrical current density, and a lower resistance compared with the ITO SL electrode.

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Hamui, Leon, and María Elena Sánchez-Vergara. "Innovative Implementation of an Alternative Tetrathiafulvene Derivative for Flexible Indium Phthalocyanine Chloride-Based Solar Cells." Micromachines 12, no. 6 (May 29, 2021): 633. http://dx.doi.org/10.3390/mi12060633.

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Herein, we present the photovoltaic properties of an indium phthalocyanine chloride (InClPc)-based flexible planar heterojunction device, introducing the tetrathiafulvene derivative 4,4′-Dimethyl-5,5′-diphenyltetrathiafulvalene (DMDP-TTF) as the electron donor layer. UV-vis spectroscopy is widely used to characterize the electronic behavior of the InClPc/DMDP-TTF active layer. The interactions between the DMDP-TTF and phthalocyanine are predominantly intermolecular and the result of the aggregation of InClPc. Tauc bands were obtained at 1.41 and 2.8 eV; these energy peaks can result in a charge transfer ascribed to the transition from the DMDP-TTF to π-orbitals that are associated with the phthalocyanine ring or even with the same indium metal center. Conductive carbon (CC) was used for the cathode. Finally, an indium tin oxide (ITO)/InClPc/DMDP-TTF/CC device was fabricated by high-vacuum thermal evaporation onto a flexible substrate and the photovoltaic properties were evaluated. A diode type I-V curve behavior was observed with a photovoltaic response under illumination. A generated photocurrent of 2.25 × 10−2 A/cm2 was measured. A conductivity reduction with the incident photon energy from 1.61 × 10−7 S/cm to 1.43 × 10−7 S/cm is observed. The diode resistance presents two different behaviors with the applied voltage. A VTFL of 5.39 V, trap concentration of 7.74 × 1016 cm−3, and carrier mobility values of ~10−6 cm2/V s were calculated, showing improved characteristics via the innovative implementation of an alternative TTF-derivative, indicating that the DMDP-TTF has a strong interaction at the junction where free available states are increased, thus inducing higher mobilities due to the large number of π-orbitals, which indicates the feasibility of its use in solar cells technology.

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Li, Wen Bo, Yin Gai Jin, Shuang Yin, and Pei Yan Chen. "Electrical Simulation Experiment and the Analysis of Thermal Conductivity of Materials." Advanced Materials Research 989-994 (July 2014): 599–602. http://dx.doi.org/10.4028/www.scientific.net/amr.989-994.599.

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s: Jilin university innovation experiment Electrical Simulation Experiment and the Analysis of Thermal Conductivity of Materials aims to solve the problem of thermocouple measuring tenderness in error. Thermocouple is used to measure temperature when measuring unsteady heat conduction in laboratory. The improved measuring method of unsteady heat conduction puts the breakthrough on the electric simulation method. The text bench is constructed by different shapes of conductive plate which is made of the graphite conductive paint, and voltmeter is refitted by diodes and controlled transformer. Through the test bench, we finished the simulation of unsteady heat conduction under the similar thermal conductive boundary conditions. Finally, the error analysis of experiment and the advantages of electric simulation method are given in this paper.

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Choi, Won Suk, Sung Mo Young, Richard L. Woodin, A. W. Witt, and J. Shovlin. "A High Performance CCM PFC Circuit Using a SiC Schottky Diode and a Si SuperFET^TM Switch." Materials Science Forum 600-603 (September 2008): 1235–38. http://dx.doi.org/10.4028/www.scientific.net/msf.600-603.1235.

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SuperFETTM MOSFETs and silicon carbide (SiC) Schottky diodes are applied to continuous conduction mode active power factor correction pre-regulators. SuperFETTM MOSFETs can reduce power losses dramatically with their extremely low RDS(ON) and fast switching. The SiC Schottky diode has virtually zero reverse recovery current and high thermal conductivity, and is close to an ideal diode for a CCM PFC circuit. Due to these outstanding switching characteristics, frequency can be increased. In this paper, the SiC Schottky diode’s and SuperFETTM MOSFET’s performance have been verified in a CCM PFC boost converter. These products can reduce the total power losses and enhance the system efficiency.

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Wu, Jiupeng, Na Ren, Qing Guo, and Kuang Sheng. "A Comparative Study of Silicon Carbide Merged PiN Schottky Diodes with Electrical-Thermal Coupled Considerations." Materials 13, no. 11 (June 11, 2020): 2669. http://dx.doi.org/10.3390/ma13112669.

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A comparative study of surge current reliability of 1200 V/5 A 4H-SiC (silicon carbide) MPS (Merged PiN Schottky) diodes with different technologies is presented. The influences of device designs in terms of electrical and thermal aspects on the forward conduction performance and surge current capability were studied. Device forward characteristics were simulated and measured. Standard single-pulse surge current tests and thermal impedance measurements were carried to show their surge capability and thermal design differences. An advanced thermal RC (thermal resistance-capacitance) model, with the consideration of current distribution non-uniformity effects, is proposed to accurately calculate the device junction temperature during surge events. It was found that a thinner substrate and a hexagonal layout design are beneficial to the improvement of the bipolar conduction performance in high current mode, as well as the surge current capability. The thinner substrate design also has advantages on thermal aspects, as it presents the lowest thermal resistance. The calculated failure temperature during the surge tests is consistent with the aluminum melting phenomenon, which is regarded as the failure mechanism. It was demonstrated that, for a SiC MPS diode, higher bipolar conduction performance is conducive to restraining the joule heat, and a lower thermal resistance design is able to accelerate the heat dissipation and limit the junction temperature during surge events. In this way, the MPS diode using a thinner substrate and advanced layout design technology is able to achieve 60% higher surge current density capability compared to the other technologies.

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Ruan, Kunpeng, Yongqiang Guo, Chuyao Lu, Xuetao Shi, Tengbo Ma, Yali Zhang, Jie Kong, and Junwei Gu. "Significant Reduction of Interfacial Thermal Resistance and Phonon Scattering in Graphene/Polyimide Thermally Conductive Composite Films for Thermal Management." Research 2021 (February 23, 2021): 1–13. http://dx.doi.org/10.34133/2021/8438614.

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The developing flexible electronic equipment are greatly affected by the rapid accumulation of heat, which is urgent to be solved by thermally conductive polymer composite films. However, the interfacial thermal resistance (ITR) and the phonon scattering at the interfaces are the main bottlenecks limiting the rapid and efficient improvement of thermal conductivity coefficients (λ) of the polymer composite films. Moreover, few researches were focused on characterizing ITR and phonon scattering in thermally conductive polymer composite films. In this paper, graphene oxide (GO) was aminated (NH2-GO) and reduced (NH2-rGO), then NH2-rGO/polyimide (NH2-rGO/PI) thermally conductive composite films were fabricated. Raman spectroscopy was utilized to innovatively characterize phonon scattering and ITR at the interfaces in NH2-rGO/PI thermally conductive composite films, revealing the interfacial thermal conduction mechanism, proving that the amination optimized the interfaces between NH2-rGO and PI, reduced phonon scattering and ITR, and ultimately improved the interfacial thermal conduction. The in-plane λ (λ∥) and through-plane λ (λ⊥) of 15 wt% NH2-rGO/PI thermally conductive composite films at room temperature were, respectively, 7.13 W/mK and 0.74 W/mK, 8.2 times λ∥ (0.87 W/mK) and 3.5 times λ⊥ (0.21 W/mK) of pure PI film, also significantly higher than λ∥ (5.50 W/mK) and λ⊥ (0.62 W/mK) of 15 wt% rGO/PI thermally conductive composite films. Calculation based on the effective medium theory model proved that ITR was reduced via the amination of rGO. Infrared thermal imaging and finite element simulation showed that NH2-rGO/PI thermally conductive composite films obtained excellent heat dissipation and efficient thermal management capabilities on the light-emitting diodes bulbs, 5G high-power chips, and other electronic equipment, which are easy to generate heat severely.

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Hsu, Cheng Yi, and Yu Li Lin. "Thermal Characteristics of High-Power LED Packages with Dissipation Film." Applied Mechanics and Materials 397-400 (September 2013): 1767–71. http://dx.doi.org/10.4028/www.scientific.net/amm.397-400.1767.

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A simple, fast, and reliable characterization method for measuring junction temperature (Tj) on high power GaN-based light emitting diodes (LED) was presented in this study. Thermal characteristics of high power Light-emitting-diode have been analyzed by using a three-dimensional thermal conduction model. Maximum operation temperature has also been calculated. The induced thermal behaviors of the best package processes for LED device with diamond film were investigated by finite element analysis (FEA) and by experimental measurement. The large change of forward operation voltage with temperature in light emitting diodes is advantageously used to measure junction temperature. Using this method, junction temperature (Tj) of LED under various structures and chip mounting methods was measured. It was found that the junction temperature can be reduced considerably by using diamond film substrates to replace sapphire substrate. In this study, the junction temperature can be decreased by about 14.3% under 1.5W power and decreased by about 15.9% under 1W power for 1mm square die. The thermal resistance (RT) can be measured to be 14.8°C/W under 1.5W power and 16.6°C/W under 1.W power.

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XI, Y., and E. F. SCHUBERT. "JUNCTION-TEMPERATURE MEASUREMENTS IN GaN UV LIGHT-EMITTING DIODES USING THE DIODE FORWARD VOLTAGE." International Journal of High Speed Electronics and Systems 14, no. 03 (September 2004): 708–13. http://dx.doi.org/10.1142/s0129156404002715.

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A theoretical model for the dependence of the diode forward voltage (V f ) on junction temperature (T) is developed. A new expression for d V f / d T is derived that takes into account all relevant contributions to the temperature dependence of the forward voltage including the intrinsic carrier concentration, the bandgap energy, and the effective density of states. Experimental results on the junction temperature of GaN UV LEDs are presented. Excellent agreement between the theoretical and experimental temperature coefficient of the forward voltage ( d V f / d T) is found. The experimentally found linear dependence of the junction temperature on forward current is explained by a thermal conduction model. A thermal resistivity of 342.2 K/W is found for the UV LED.

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Richstein, Benjamin, Lena Hellmich, and Joachim Knoch. "Silicon Nitride Interface Engineering for Fermi Level Depinning and Realization of Dopant-Free MOSFETs." Micro 1, no. 2 (November 21, 2021): 228–41. http://dx.doi.org/10.3390/micro1020017.

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Problems with doping in nanoscale devices or low temperature applications are widely known. Our approach to replace the degenerate doping in source/drain (S/D)-contacts is silicon nitride interface engineering. We measured Schottky diodes and MOSFETs with very thin silicon nitride layers in between silicon and metal. Al/SiN/p-Si diodes show Fermi level depinning with increasing SiN thickness. The diode fabricated with rapid thermal nitridation at 900 ∘C reaches the theoretical value of the Schottky barrier to the conduction band ΦSB,n=0.2 eV. As a result, the contact resistivity decreases and the ambipolar behavior can be suppressed. Schottky barrier MOSFETs with depinned S/D-contacts consisting of a thin silicon nitride layer and contact metals with different work functions are fabricated to demonstrate unipolar behavior. We presented n-type behavior with Al and p-type behavior with Co on samples which only distinguish by the contact metal. Thus, the thermally grown SiN layers are a useful method suppress Fermi level pinning and enable reconfigurable contacts by choosing an appropriate metal.

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Machado, H. A., and A. G. Ramos. "PERFORMANCE ANALYSIS OF THERMAL DIODES." Revista de Engenharia Térmica 5, no. 2 (December 31, 2006): 66. http://dx.doi.org/10.5380/reterm.v5i2.61853.

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The thermal diode consists in a common brick empty inside, where the internal cavity is geometrically arranged as two rectangles, disposed one over the other but not aligned. When the lower side is heated, natural convection in the air inside yields high heat transfer rates from this side to the other. When the upper side is heated, the heat transfer should run by pure conduction, and the brick with air inside works as a thermal insulator. As this brick allows a good conductance in one direction and insulation in the opposite sense, it behaves as an electric diode, being known as thermal diode. This principle is already known for a long time, but its use is still not extensive, and there are no basic rules for the cavity design or even a theoretical study of viability for this use replacing the conventional insulation systems. The objective of this work is to simulate the heat transfer process inside a thermal diode, in order to obtain the optimal geometry and dimensions and to verify the viability of its use in buildings for thermal optimization. The numerical data are validated through comparing with that obtained from the test applied to cellular concrete bricks.

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Lisik, Zbigniew, Ewa Raj, and Jacek Podgórski. "Numerical Model of Current Flow and Thermal Phenomena in Lateral GaN/InGaN LEDs." Electronics 10, no. 24 (December 16, 2021): 3127. http://dx.doi.org/10.3390/electronics10243127.

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GaN-based light-emitting diodes (LEDs) became one of the most widely used light sources. One of their key factors is power conversion efficiency; hence, a lot of effort is placed on research to improve this parameter, either experimentally or numerically. Standard approaches involve device-oriented or system-oriented methods. Combining them is possible only with the aid of compact, lumped parameter models. In the paper, we present a new electro-thermal model that covers all the complex opto-electro-thermal phenomena occurring within the operating LED. It is a simple and low computational cost solution that can be integrated with package- or system-oriented numerical analysis. It allows a parametric analysis of the diode structure and properties under steady-state operating conditions. Its usefulness has been proved by conducting simulations of a sample lateral GaN/InGaN LED with the aid of ANSYS software. The results presented illustrate the current density and temperature fields. They allow the identification of ‘hot spots’ resulting from the current crowding effect and can be used to optimise the structure.

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Scofield, James D., Joseph Neil Merrett, Jim Richmond, Anant K. Agarwal, and Scott Leslie. "Electrical and Thermal Performance of 1200 V, 100 A, 200°C 4H-SiC MOSFET-Based Power Switch Modules." Materials Science Forum 645-648 (April 2010): 1119–22. http://dx.doi.org/10.4028/www.scientific.net/msf.645-648.1119.

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In this paper we report the electrical and thermal performance characteristics of 1200 V, 100 A, 200°C (Tj), SiC MOSFET power modules configured in a dual-switch topology. Each switch-diode pair was populated by 2 x 56 mm2 SiC MOSFETs and 2 x 32 mm2 SiC junction barrier Schottky (JBS) diodes providing the 100 A rating at 200°C. Static and dynamic characterization, over rated temperature and power ranges, highlights the performance potential of this technology for highly efficient drive and power conversion applications. Electrical performance comparisons were also made between SiC power modules and equivalently rated and packaged IGBT modules. Even at a modest Tj=125°C, conduction and dynamic loss evaluation for 20kHz, Id=100A operation demonstrated a significant efficiency advantage (38-43%) over the IGBT components. Initial reliability data also illustrates the potential for SiC technology to provide robust performance in harsh environments.

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Oh, Weontae, Jong-Seong Bae, and Hyoung-Seok Moon. "Thermal conduction characteristics of silicone composites including ultrasonic-treated graphite." Journal of Composite Materials 56, no. 4 (December 13, 2021): 619–26. http://dx.doi.org/10.1177/00219983211059582.

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The microstructural change of graphite was studied after ultrasonic treatment of the graphite. When the graphite solution was treated with varying ultrasonic power and time, the microstructure changed gradually, and accordingly, the thermal conductivity characteristics of the composite containing the as-treated graphite was also different with each other. Thermal conductivity showed the best result in the silicone composite containing graphite prepared under the optimum condition of ultrasonic treatment, and the thermal conductivity of the composite improved proportionally along with the particle size of graphite. When the silicone composite was prepared by using a mixture of inorganic oxides and graphite rather than graphite alone, the thermal conductivity of the silicone composite was further increased. A silicone composite containing graphite was used for LED (light emitting diode) lighting system as a thermal interface material (TIM), and the temperature elevation due to heat generated, while the lighting was actually operated, was analyzed.

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34

Hao, Feng Bin, Xiao Xing Jin, Ao Liu, Shi Yan Li, Song Bai, and Gang Chen. "Research of 3.3kV, 60A H-Bridge High-Voltage SiC Diode Modules." Materials Science Forum 1014 (November 2020): 163–70. http://dx.doi.org/10.4028/www.scientific.net/msf.1014.163.

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The simulation, fabrication and measurement of the high-voltage H-bridge SiC diode module is reported. The SiC module is consisted with 8 self-designed 3.3 kV30 A SiC Schottky diodes (SBDs), in which each bridge arm is connected by double SBD chips to achieve 60A current. Q3D is used to establish simulation model and make network division of the module. Two parasitic parameters, parasitic inductor and circuit resistance, are extracted from the circuits, which are about 37.5 nH and 1.9 mΩ, respectively. By establishing the geometric model and finite element model, finite element analysis software ANSYS is used to calculate steady-state thermal conduction, and the temperature gradient distribution of the formed chips. The results show that the maximum junction temperature of the chip is about 100°C, and the distribution of the temperature field is reasonable. As the lateral conduction of heat increases the effective heat dissipation area, there is no obvious concentration of heat. Under the condition of the test at room temperature and static, the module voltage drop is about 2.1 V, the leakage current is less than 5 uA, and the breakdown voltage is more than 3700 V, respectively. The fabricated 3300 V devices exhibit large safety margin. The insulation voltage exceeds 7000V, thus ensure the safety of the system. The thermal resistance of the chip is about 0.21 K/W, which is basically consistent with the simulation results.

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Fisher, Craig A., Michael R. Jennings, Angus T. Bryant, Amador Pérez-Tomás, Peter M. Gammon, Pierre Brosselard, Phillippe Godignon, and Philip A. Mawby. "Physical Modelling of 4H-SiC PiN Diodes." Materials Science Forum 717-720 (May 2012): 993–96. http://dx.doi.org/10.4028/www.scientific.net/msf.717-720.993.

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With the recent technological advances in 4H-SiC PiN diode fabrication, simulation tools which enable the accurate and rapid prediction of losses of such devices in power electronics circuits will be increasingly sought-after. To this end, a physical electro-thermal model of the 4H-SiC PiN diode has been developed, which facilitates device optimization for power circuit applications. The performance of this model has been compared with both finite element simulations and experimental results; good matching for both switching and conduction characteristics has been observed.

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Datta, Madhav. "Bonded Ceramic-Metal Layers for Fabrication of Thermal Conduction Plates." Journal of Microelectronics and Electronic Packaging 12, no. 3 (July 1, 2015): 146–52. http://dx.doi.org/10.4071/imaps.473.

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The work described in this article is part of an effort to build reliable and efficient liquid cooling modules for high-power laser diodes. The cooling system is designed to mount at least 12 laser diodes to a common microheat exchanger, thus requiring a large-size thermal conduction plate. Fabrication of the thermal conduction plate involved void-free bonding of copper layers on both sides of an aluminum nitride (AlN) plate. In the current study, ceramic-metal bonding methods using moly-manganese metallization and active metal brazing were investigated. Bonded AlN/copper plates were characterized and evaluated by optical microscopy, scanning electron microscopy, and energy dispersive spectrometry. For detecting voids, cracks, and delamination, some of the plates were analyzed by scanning acoustic microscopy (C-SAM). Results indicated that >99% void-free bonded AlN/Cu plates can be fabricated by using properly selected metallization conditions and brazing temperature profiles. The active metal brazing approach was found to be a cost-effective method of fabricating reliable, void-free thermal conduction plates.

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Dong, Yuan. "Thermal rectification based on phonon hydrodynamics and thermomass theory." Communications in Applied and Industrial Mathematics 7, no. 2 (June 1, 2016): 26–38. http://dx.doi.org/10.1515/caim-2016-0004.

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AbstractThe thermal diode is the fundamental device for phononics. There are various mechanisms for thermal rectification, e.g. different temperature dependent thermal conductivity of two ends, asymmetric interfacial resistance, and nonlocal behavior of phonon transport in asymmetric structures. The phonon hydrodynamics and thermomass theory treat the heat conduction in a fluidic viewpoint. The phonon gas flowing through the media is characterized by the balance equation of momentum, like the Navier-Stokes equation for fluid mechanics. Generalized heat conduction law thereby contains the spatial acceleration (convection) term and the viscous (Laplacian) term. The viscous term predicts the size dependent thermal conductivity. Rectification appears due to the MFP supersession of phonons. The convection term also predicts rectification because of the inertia effect, like a gas passing through a nozzle or diffuser.

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Refai-Ahmed, Gamal, and Stephanie Trottier. "Thermal Performance of Next Generation of Modulated Pump Lasers in Telco Equipment." Journal of Electronic Packaging 126, no. 4 (December 1, 2004): 535–40. http://dx.doi.org/10.1115/1.1773199.

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The present investigation numerically modeled the thermal behavior of the laser diode using the parabolic transient conduction equation. In addition, the current study compared the thermal performance of the continuous wave pump lasers versus the modulated wave pump lasers. This comparison revealed that the temperature of the modulated wave pump laser can approach the temperature of the continuous wave pump laser with the same average power dissipation when the frequency approaches infinity. Finally, the resulting thermal behavior was correlated and expressed in an empirical form, which physically described the thermal performance of the modulating pump laser.

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Li Long, 李隆, 史霞 Shi Xia, 杜长龙 Du Changlong, 董武威 Dong Wuwei, 齐兵 Qi Bing, and 史彭 Shi Peng. "Transient Thermal Analysis of Anisotropic Thermal Conduction Laser Slab with Pulsed-Diode-Bar Side-Pumping." Laser & Optoelectronics Progress 48, no. 10 (2011): 101406. http://dx.doi.org/10.3788/lop48.101406.

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Liu, Lin Lin, Ting Gang Zhu, Michael Murphy, Marek Pabisz, Milan Pophristic, Boris Peres, and Tom Hierl. "600V GaN Schottky Barrier Power Devices for High Volume and Low Cost Applications." Materials Science Forum 600-603 (September 2008): 1251–56. http://dx.doi.org/10.4028/www.scientific.net/msf.600-603.1251.

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The first commercially viable high voltage (>600V) gallium nitride (GaN) Schottky barrier devices are reported. Though GaN does not have any “micropipe” defects, which commonly exists in SiC material, defects like dislocations due to lattice mismatch hamper the material development of GaN high power devices. Improvements in the nitride epitaxial film growth have led to significant reduction of conductive dislocations. Conductive Atomic Force Microscope (CAFM) analysis of conductive dislocations shows only on the order of 103 cm-2 density of conductive dislocations, which are believed to be responsible for the undesired leakage current. GaN diodes compare to SiC or Si devices demonstrate a significant advantage in the thermal resistance. The insulating properties of Sapphire substrates allow fabrication of the devices in TO220 packages with insulating frame and thermal resistance better than 1.8°C/W compare to 3°C/W of SiC or Si devices with insulating frame. Performance of GaN, SiC and Si devices in the switch mode power supplies is compared.

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Zhang, Lulu, Yangyang Xie, Zhongzhi Tian, Yixuan Liu, Chong Geng, and Shu Xu. "Thermal Conductive Encapsulation Enables Stable High-Power Perovskite-Converted Light-Emitting Diodes." ACS Applied Materials & Interfaces 13, no. 25 (June 21, 2021): 30076–85. http://dx.doi.org/10.1021/acsami.1c07194.

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Tian, Zhuo, and Bai Cheng Li. "Conduction Uniformity Improvement of ESD Protection Device in 0.35 μm Partially-Depleted SOI Salicided CMOS Technology." Applied Mechanics and Materials 687-691 (November 2014): 3251–54. http://dx.doi.org/10.4028/www.scientific.net/amm.687-691.3251.

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ComparedtobulkCMOStechnology,Silicon-on-Insulator (SOI) CMOS technology has many advantages, such as low power consumption, low leakage current, low parasitic capacitance and a low soft error rate from both alpha particles and cosmic rays. However,electrostatic discharge (ESD) protection in SOI technology is still a major substantial barrier to overcome for the poor thermal conductivity of isolation oxide and the absence of vertical diode and silicon controlled rectifier (SCR).

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Wei, Cheng, Lu, Siwakoti, and Zhang. "Multi-Variable Thermal Modeling of Power Devices Considering Mutual Coupling." Applied Sciences 9, no. 16 (August 8, 2019): 3240. http://dx.doi.org/10.3390/app9163240.

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In relation to power converter design, power density is increasing while the form factor isdecreasing. This trend generally reduces the rate of the cooling process, which increases the mutualthermal coupling among the surrounding power components. Most of the traditional modelsusually ignore the mutual effects or just focus on the conduction coupling. To deal with these factors,the thermal modeling for a boost converter system has been built to compare the junctiontemperatures (Tj) and the increments under different working conditions in order to consider theconduction coupling. A multi-variable thermal resistances model is proposed in this paper toincorporate the convection thermal coupling into the mutual thermal effects. The couplingresistances, MOSFET to the diode[...]

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Yi, Mingming, Meng Han, Junlin Chen, Zhifeng Hao, Yuanzhou Chen, Yimin Yao, and Rong Sun. "A Novel Method to Prepare Transparent, Flexible and Thermally Conductive Polyethylene/Boron Nitride Films." Nanomaterials 12, no. 1 (December 30, 2021): 111. http://dx.doi.org/10.3390/nano12010111.

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The high thermal conductivity and good insulating properties of boron nitride (BN) make it a promising filler for high-performance polymer-based thermal management materials. An easy way to prepare BN-polymer composites is to directly mix BN particles with polymer matrix. However, a high concentration of fillers usually leads to a huge reduction of mechanical strength and optical transmission. Here, we propose a novel method to prepare polyethylene/boron nitride nanoplates (PE/BNNPs) composites through the combination of electrostatic self-assembly and hot pressing. Through this method, the thermal conductivity of the PE/BNNPs composites reach 0.47 W/mK, which gets a 14.6% improvement compared to pure polyethylene film. Thanks to the tight bonding of polyethylene with BNNPs, the tensile strength of the composite film reaches 1.82 MPa, an increase of 173.58% compared to that of pure polyethylene film (0.66 MPa). The fracture stress was also highly enhanced, with an increase of 148.44% compared to pure polyethylene film. Moreover, the addition of BNNPs in PE does not highly reduce its good transmittance, which is preferred for thermal management in devices like light-emitting diodes. This work gives an insight into the preparation strategy of transparent and flexible thermal management materials with high thermal conductivity.

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Vivona, Marilena, Kassem Al Assaad, Véronique Soulière, Filippo Giannazzo, Fabrizio Roccaforte, and Gabriel Ferro. "Electrical Characteristics of Schottky Contacts on Ge-Doped 4H-SiC." Materials Science Forum 778-780 (February 2014): 706–9. http://dx.doi.org/10.4028/www.scientific.net/msf.778-780.706.

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We report on the electrical characteristics of Ni/4H-SiC Schottky contacts fabricated on a Ge-doped 4H-SiC epilayer. The morphology and the current mapping carried out by conductive atomic force microscopy on the epilayer allowed observing nanoscale preferential conductive paths on the sample surface. The electrical characteristics of Ni contacts have been studied before and after a rapid thermal annealing process. A highly inhomogeneous Schottky barrier was observed in as-deposited diodes, probably related to the surface electrical inhomogeneities of the 4H-SiC epilayer. A significant improvement of the Schottky diodes characteristics was achieved after annealing at 700°C, leading to the consumption of the near surface epilayer region by Ni/4H-SiC reaction. After this treatment, the temperature behavior of the ideality factor and Schottky barrier height was comparable to that observed on commercial 4H-SiC material.

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Bomba, A. Ya, and I. P. Moroz. "THE DIFFUSION-DRIFT PROCESS WITH ACCOUNT HEATING AND RECOMBINATION IN THE p-i-n DIODES ACTIVE REGION MATHEMATICAL MODELING BY THE PERTURBATION THEORY METHODS." Journal of Numerical and Applied Mathematics, no. 1 (135) (2021): 29–35. http://dx.doi.org/10.17721/2706-9699.2021.1.03.

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With prolonged transmission of an electric current through the semiconductor devices, in a particular p-i-n diodes, an electron-hole plasma of their active region is heated. This paper presents the theoretical studies results of the plasma heating effect by the Joule heat release in the p-i-n diode volume and the charge carriers recombination energy release on the plasma concentration distribution in the p-i-n diodes active region. The mathematical model is proposed for predicting the electron-hole plasma stationary concentration distribution and the temperature field in the i-region of the bulk p-i-n diodes in the form of a nonlinear boundary value problem in a given area for the equations system, which consist of the charge carrier current continuity equations, the Poisson and the thermal conductivity. It is shown that the differential equations of the model contain a small parameter in such a way that the Poisson equation is singularly perturbed and the heat conduction equation is regularly perturbed. An approximate solution of the problem posed is obtained in the form of the corresponding asymptotic series in powers of the small parameter. The asymptotic serieses, which describes the behavior of the plasma concentration and potential in the investigated region, containing near-boundary corrections to ensure the fulfillment of the boundary conditions. The terms of these series are found as a result of solving a sequence of boundary value problems, obtained as a result of splitting the original problem, for systems of linear differential equations. The boundary value problem for a nonlinear heat equation is reduced to a sequence of problems for the corresponding linear inhomogeneous equations. The process of refining solutions is iterative. The stabilization of the process is ensured by the existence of negative feedback in the system (as the temperature rises, the mobility of charge carriers decreases).

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Rahimo, Munaf, and Liutauras Storasta. "Optimization and advantages of the Bi-mode insulated gate transistor." Facta universitatis - series: Electronics and Energetics 28, no. 3 (2015): 383–91. http://dx.doi.org/10.2298/fuee1503383r.

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The Bi-mode Insulated Gate Transistor BIGT is a single chip reverse conducting IGBT concept, which is foreseen to replace the standard IGBT / Diode two chip approach in many high power semiconductor applications. Therefore, it is important to understand in detail the design challenges and performance trade-offs faced when optimizing the BIGT for different application requirements. In this paper, we present the main conflicting design trade-offs for achieving the overall electrical and thermal performance targets. We will demonstrate experimentally how on one hand, the BIGT provides improved design features which overcome the restrictions of the current state of the art IGBT/diode concepts, while on the other hand, a new set of tailoring parameters arise for an optimum BIGT behavior.

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Gaewdang, Thitinai, and Ngamnit Wongcharoen. "Electrical Conduction Mechanisms in n-CdS/p-CuFeO₂ Heterojunction Diode." Advanced Materials Research 931-932 (May 2014): 122–26. http://dx.doi.org/10.4028/www.scientific.net/amr.931-932.122.

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In this work, n-CdS/p-CuFeO2 heterojunction diode was fabricated by thermal evaporating CdS thin films on 1 mm thick-CuFeO2 ceramic substrate with substrate temperature kept at 373 K during evaporation process. The forward current-voltage characteristics of n-CdS/p-CuFeO2 heterojunction in a temperature range of 100-300 K were investigated to determine the electrical parameters and conduction mechanism. It was found that, at forward bias below 0.5 V, the conduction mechanism of the diode is dominated by thermionic emission (TE) mechanism. At bias voltage above 0.5 V, the current transport is due to space charge limited current (SCLC) controlled by an exponential trap distribution in the band gap of CdS. The temperature dependence of the saturation current and ideality factor are well described by tunneling enhanced recombination at junction interface with activation and characteristic tunneling energy values as about 1.79 eV and E00 = 86 meV, respectively. The value of interface state density (Nss) evaluated from capacitance spectroscopy increases from 2.09x1011 eV-1cm-2 (at 300 K) to 2.70x1011 eV-1cm-2 (at 363 K). Free carrier concentration of 5.80x1013 cm-3 at room temperature was estimated from capacitance-voltage measurements at 50 kHz.

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Zhang, Q., Zi Yang Xiu, Mei Hui Song, and Gao Hui Wu. "Microstructure and Properties of a 70vol.% SiCp/Al-12Si Composite for Electronic Packaging." Materials Science Forum 475-479 (January 2005): 881–84. http://dx.doi.org/10.4028/www.scientific.net/msf.475-479.881.

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For the purpose of electronic packaging applications, a homogenous and void free 4032Al (Al-12wt.%Si) matrix composite with 70vol.% SiC particles was fabricated by squeeze casting technology. TEM observations indicated that SiC particles acted as heterogeneous nucleation sites for Si phases in the matrix and the SiC-Al interfaces were clean and free from any interfacial reaction products. The composite possessed lower coefficients of thermal expansion (CTEs) and excellent thermal conduction properties, and the CTEs could be further reduced by annealing treatment because of the alteration of original thermal residual stresses within the specimens. The incorporation of high volume fraction of SiC particles also induced enhanced mechanical properties for the composite, and its moduli even exceeded 200GPa. Some diodes were finally produced with nickel plated SiCp/Al baseplates and the results of thermal cycling tests between -55ı and 150ıfor these diodes were presented.

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Hsu, Chih-Neng, Keng-Wei Lee, and Chun-Chih Chen. "Using Graphene-Based Grease as a Heat Conduction Material for Hectowatt-Level LEDs: A Natural Convection Experiment." Processes 9, no. 5 (May 12, 2021): 847. http://dx.doi.org/10.3390/pr9050847.

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Abstract:

In this study, a self-adjusting concentration of graphene thermal grease was developed to reduce the contact surface thermal resistance of 50 W light-emitting diodes (LEDs). The purpose was to identify an important type of heat conduction material with a high thermal conductivity coefficient, which can be applied to the contact surface of various high-heat sources or concentrated heat sources to achieve seamless heat transfer with an extremely low thermal resistance state. The contact heat conduction material conductivity reached the highest K value of 13.4 W/m·K with a 15 wt.% self-adjusting concentration of graphene grease. This material could continuously achieve a completely uniform and rapid thermal diffusion of heat energy. Therefore, we performed an analysis of chip-on-board light-emitting diodes (LEDs) with a highly concentrated heat source, which showed excellent heat dissipation under natural convection heat transfer. As such, this study achieved the natural convection mechanism and a heat sink volume thermal performance capacity of 473,750 mm3 for LEDs under 50 W, but those over 50 W require an enhanced forced convection solution and a heat sink volume thermal performance capacity between 473,750 mm3 and 947,500 mm3. If the heat source dissipation reaches 100 W, the volume capacity must be at least 947,500 mm3 for lighting equipment applications. In the experimental study, we also verified and analyzed the research data, including an analysis of the measured data, grease component wt.%, heat sink material selection, increase in heat sink volume, heat transfer path, and contact surface, a discrimination analysis of infrared thermal images, and an analysis of flow visualization, which were conducted to ensure quantitative and qualitative improvement, provide a mechanism for judging the technical performance, and provide research results to enable discussion.

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Journal articles on the topic 'Conductive thermal diode'

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