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Hexagonal boron nitride (HBN) is the preferred heat dissipation material for the next generation

A study funded by the Australian Research Council through the Science and Technology Achievement Conversion Award and led by the Dicken University Institute shows that the thermal conductivity of single-layer hexagonal boron nitride (BN) reaches 751 W / mK at room temperature, which is the second highest in all semiconductors and insulating materials per unit weight and with hexagonal nitriding. With the increase of drilling layers, the thermal conductivity gradually decreases. This also means that single-layer hexagonal boron nitride is the first choice of heat dissipation materials for the next generation of flexible electronic devices.

Diamond and cubic boron nitride (CBN) were originally the highest thermal conductivity of these materials, but they are difficult to use in flexible equipment due to their cost of production and brittleness. The recently discovered high-performance 1.5 eV cubic boron arsenide (BAs) has a thermal conductivity of about 1000 W / mK, but it also questions flexibility. In contrast, the performance of highly oriented pyrolytic hexagonal BN (HOPBN) is comparable to that of monocrystalline boron nitride. Although there are many grain boundaries, defects, and dislocations, the thermal conductivity is still up to 400 W / mK at room temperature.

Many previous studies have found that the thermal conductivity of some BN layers is not even as good as that of a common HBN block. Some experimental data even show that the thermal conductivity of five BN layers is worse than that of 11 BN layers. The researchers think that there were previously defects in hBN samples. In addition, the use of polymers (such as PMMA) is involved in the sample transfer process and there is residual contamination. Therefore, the experimental results are inevitably destroyed.

This experiment used transparent tape to make single layer BN (similar to the original Nobel Prize winner method for preparing graphene), and Raman spectroscopy was used to measure the results. Researchers covered the single layer of BN separately on the silicon substrate covered with nano-silica and the gold-plated silicon substrate, both of which were machined and equipped with prefabricated micropore and groove to prevent gas expansion during heating.

Finally, by preparing high-quality single-layer BN and conducting experiments, the researchers revealed the inherent thermal conductivity of the material. The results show that in a semiconductor and insulator, the single BN layer has the highest thermal conductivity except for diamond and cubic boron arsenide. But it also has many advantages, such as low density, high strength, high toughness, high toughness, high stability, and impermeability, making the application possibilities particularly wide.

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