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Silicon carbide-graphene composite structure heat dissipation material

With the increase in power density of semiconductor devices, “heat dissipation” has become the primary problem that hinders the performance and life of electronic devices. According to statistics, for every 10℃-15℃ increase in the temperature of electronic devices, their corresponding service life will be reduced by 50%. Therefore, it is particularly important to develop high-performance thermal interface materials for high-power density thermal management.

Recently, the functional carbon material team of the surface division of the Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, and its collaborators prepared a high-performance thermal interface material based on graphene paper. The preparation process of this material is as follows: first, nano-silicon dioxide particles (SiO2 NPs) are modified on the surface of graphene oxide (GO) by hydrolysis of tetraethyl orthosilicate (TEOS) in a weak alkaline environment; then, the obtained GO/SiO2 NPs are mixed with graphene powder, and a composite graphene film is prepared by filtration to achieve uniform distribution of nanoscale silicon source (SiO2 NPs) between graphene layers; finally, the composite graphene film is subjected to rapid heat treatment to in-situ convert the silicon source into silicon carbide nanowires to obtain graphene hybrid paper (GHP) with a silicon carbide-graphene composite structure.

Because the silicon carbide nanowires connected between graphene layers form a longitudinal heat conduction path, the longitudinal thermal conductivity of GHP (10.9W/mK) is 60% higher than that of graphene paper (GP, 6.8W/mK). In addition, under a compressive stress of 75psi, the longitudinal thermal conductivity of GHP in the compressed state is further increased to 17.6W/mK, which is higher than traditional graphene paper and most commercial thermal interface materials, including thermal conductive silicone pads, thermal conductive silicone grease and thermal conductive gel.

In the actual thermal interface performance evaluation experiment, the temperature drop of the system with GHP as the thermal interface material is as high as 18.3℃, which is more than twice the temperature drop of commercial thermal interface materials (8.9℃), and the heat dissipation efficiency is improved by 27.3%. The simulation software simulates the heat dissipation process, and the results show that GHP not only has a higher longitudinal thermal conductivity, but also has a lower contact thermal resistance than the mainstream commercial thermal pad. In addition, compared with silicone-based commercial thermal interface materials, GHP is completely composed of inorganic silicon carbide and graphene, and has better thermal stability and environmental adaptability. The relevant work has been published in ACS Nano (2019, DOI: 10.1021/acsnano.8b07337).

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Silicon Carbide Nanowires

The diameter of silicon carbide nanowires is generally less than 500nm, and the length can reach hundreds of μm, which has a higher aspect ratio than silicon carbide whiskers. Silicon carbide nanowires inherit the various mechanical properties of silicon carbide bulk materials and also have many properties unique to low-dimensional materials. Theoretically, the Young’s modulus of a single SiCNWs is about 610~660GPa; the bending strength can reach 53.4GPa, which is about twice that of SiC whiskers; the tensile strength exceeds 14GPa. In addition, since SiC itself is an indirect bandgap semiconductor material, the electron mobility is high. Moreover, due to its nano scale size, SiC nanowires have a small size effect and can be used as a luminescent material; at the same time, SiC-NWs also show quantum effects and can be used as a semiconductor catalytic material. Nano silicon carbide wires have application potential in the fields of field emission, reinforcement and toughening materials, supercapacitors, and electromagnetic wave absorption devices.

In the field of field emission, because nano SiC wires have excellent thermal conductivity, a band gap width greater than 2.3 eV, and excellent field emission performance, they can be used in integrated circuit chips, vacuum microelectronic devices, etc.

Silicon carbide nanowires have been used as catalyst materials. With the deepening of research, they are gradually being used in photochemical catalysis. There are experiments using silicon carbide nanowires to conduct catalytic rate experiments on acetaldehyde, and compare the time of acetaldehyde decomposition using ultraviolet rays. It proves that silicon carbide nanowires have good photocatalytic properties.

Since the surface of SiC nanowires can form a large area of double-layer structure, it has excellent electrochemical energy storage performance and has been used in supercapacitors.