| Feb 14, 2023 |
High thermal conductivity of cubic silicon carbide finally demonstrated
(Nanowerk News) A research group from the Graduate School of Engineering at Osaka Metropolitan University has shown that 3C-SiC exhibits high thermal conductivity equivalent to the theoretical value, based on thermal conductivity evaluation and atomic-level analysis, for the first time (Nature Communications, "High thermal conductivity in wafer-scale cubic silicon carbide crystals"). They demonstrated that a 3C-SiC film on silicon substrate had a high thermal conductivity and expect that fabricating large-diameter wafers can be achieved at a low cost. The discovery should lead to improved heat dissipation in everyday electronic devices.
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| The measured thermal conductivity of 3C-SiC at room temperature is compared with other high thermal conductivity crystals as a function of wafer size. The shaded portion includes the data from large crystals. (Image: Jianbo Liang, Osaka Metropolitan University)
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Semiconductors are a key component in smartphones, televisions, and other devices used in daily life using these devices generates heat, resulting in performance degradation and a shorter product life due to the rise in temperature. Therefore, there is a demand for new materials with high thermal conductivity.
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Silicon carbide (SiC) is attracting significant attention as a semiconductor material for next-generation power electronics. Generally, the simpler the crystal structure, the higher the thermal conductivity. However, the thermal conductivity of 3C-SiC had not been demonstrated at theoretical levels despite having the second simplest crystal structure after diamond.
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A research group, led by Associate Professor Jianbo Liang and Professor Naoteru Shigekawa from the Osaka Metropolitan University Graduate School of Engineering, has proven for the first time that 3C-SiC exhibits high thermal conductivity, equivalent to the theoretical level, based on their thermal conductivity evaluation and atomic-level analysis.
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The research group used 3C-SiC crystals developed by Air Water Inc. First, they demonstrated that 3C-SiC crystals exhibit high thermal conductivity among large-diameter materials, where they were second only to diamond. Then, they showed that a thin film of 3C-SiC crystals—one-fiftieth the thickness of a hair—could exhibit a thermal conductivity higher than that of diamond, which also corresponded to the theoretical value.
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Next, they performed an atomic-level analysis to investigate why they were able to measure the high thermal conductivity, which had not been previously observed. They found that the 3C-SiC crystal contained almost no impurities: the atoms in the crystal were regularly arranged, indicating a very high-quality single crystal.
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Furthermore, they formed 3C-SiC crystals on a silicon substrate and performed an atomic-level analysis of the thermal conductivity of the interface, which revealed no significant disorder in the atomic arrangement at the interface and exhibited a high thermal conductance.
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“Both the freestanding 3C-SiC crystal and thin films on a silicon substrate have high thermal conductivity and we expect large-diameter wafers can be fabricated at a low cost. This should lead to improved heat dissipation on a practical level in electronic devices,” concluded Professor Liang.
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