[China Instruments Network Instrument Development] The grain boundary is a common defect in large area graphene films prepared by chemical vapor deposition (CVD) methods. An in-depth understanding of the influence of grain boundaries on the electrical and thermal properties of graphene is of great significance for the development of graphene-based electronic, optoelectronic and thermoelectric devices.
The Effect of Uniformly Adjustable Grain Sizes on the Thermal Conductivity and Electrical Conductivity of Graphene Prepared by "Precipitation-Surface Adsorption Growth" CVD Method
Although there are many studies on the effect of individual grain boundaries on the properties of graphene, the influence of grain size on the electrical and thermal properties of graphene at the macroscopic scale is still unclear. The main reason is that the CVD growth method based on the traditional precipitation (nickel matrix) or surface adsorption growth (copper matrix) mechanism cannot control the graphene grain size in a large range, and the grain size is smaller than the mean electron and phonon mean free path. Small crystalgrain (about 1 micron) is particularly difficult.
Recently, the graphene research group of the Advanced Carbon Materials Research Division of Shenyang National Institute of Materials Science, Chinese Academy of Sciences Institute of Metals, adopted a metal platinum sheet with a moderate amount of carbon as a growth substrate, and developed a method based on “precipitation-surface adsorption growthâ€. The principle CVD method realizes the control of graphene nucleation density only by changing the precipitation temperature, and produces a high-quality single crystal grain size that is uniformly adjustable in the range of ~200 nanometers to ~1 micrometer, and the grain boundaries are perfectly combined. Polycrystalline graphene film. On this basis, the influence of grain size on the electrical conductivity and thermal conductivity of polycrystalline graphene was obtained, and the grain boundary electrical resistivity (~0.3 kW·μm) and grain boundary thermal conductance (~3.8×109 Wm-2K) were obtained. -1) It was found that reducing the grain size can result in a significant reduction in thermal conductivity but less in the electrical conductivity.
According to the influence rule, when the grain size of graphene is reduced from 1 mm to 5 nm, the thermal conductivity of the graphene can be reduced by 300 times, while the attenuation of the electrical conductivity is only about 10 times, and the thermal conductivity. The change rate of the electrical conductivity with the change of the grain size is higher than that of a typical semiconductor thermoelectric material.
The above results can provide useful guidance for the application of graphene in electrical, optoelectronic and thermoelectric fields by controlling the electrical and thermal properties of graphene through grain size engineering. This achievement was supported by the Ministry of Science and Technology's key research and development program, the National Natural Science Foundation of China's Outstanding Youth Fund, major projects, innovative groups, and key deployment projects of the Chinese Academy of Sciences. It was published online on Nature-Communications on February 16 (Nature Communications , 8:14486, DOI: 10.1038/ncomms14486, 2017).
Shenyang Institute of Materials Science Shenyang (China) Laboratory of Solid Atomic Image Science Ma Xiuliang Research Group, Suning University Xu Ningsheng Research Group and Zhejiang University Jin Chuanhong Research Group researchers also participated in the study.
(Original title: Progress in research on control of crystalline domain size and electrical and thermal properties of graphene)
The Effect of Uniformly Adjustable Grain Sizes on the Thermal Conductivity and Electrical Conductivity of Graphene Prepared by "Precipitation-Surface Adsorption Growth" CVD Method
Although there are many studies on the effect of individual grain boundaries on the properties of graphene, the influence of grain size on the electrical and thermal properties of graphene at the macroscopic scale is still unclear. The main reason is that the CVD growth method based on the traditional precipitation (nickel matrix) or surface adsorption growth (copper matrix) mechanism cannot control the graphene grain size in a large range, and the grain size is smaller than the mean electron and phonon mean free path. Small crystalgrain (about 1 micron) is particularly difficult.
Recently, the graphene research group of the Advanced Carbon Materials Research Division of Shenyang National Institute of Materials Science, Chinese Academy of Sciences Institute of Metals, adopted a metal platinum sheet with a moderate amount of carbon as a growth substrate, and developed a method based on “precipitation-surface adsorption growthâ€. The principle CVD method realizes the control of graphene nucleation density only by changing the precipitation temperature, and produces a high-quality single crystal grain size that is uniformly adjustable in the range of ~200 nanometers to ~1 micrometer, and the grain boundaries are perfectly combined. Polycrystalline graphene film. On this basis, the influence of grain size on the electrical conductivity and thermal conductivity of polycrystalline graphene was obtained, and the grain boundary electrical resistivity (~0.3 kW·μm) and grain boundary thermal conductance (~3.8×109 Wm-2K) were obtained. -1) It was found that reducing the grain size can result in a significant reduction in thermal conductivity but less in the electrical conductivity.
According to the influence rule, when the grain size of graphene is reduced from 1 mm to 5 nm, the thermal conductivity of the graphene can be reduced by 300 times, while the attenuation of the electrical conductivity is only about 10 times, and the thermal conductivity. The change rate of the electrical conductivity with the change of the grain size is higher than that of a typical semiconductor thermoelectric material.
The above results can provide useful guidance for the application of graphene in electrical, optoelectronic and thermoelectric fields by controlling the electrical and thermal properties of graphene through grain size engineering. This achievement was supported by the Ministry of Science and Technology's key research and development program, the National Natural Science Foundation of China's Outstanding Youth Fund, major projects, innovative groups, and key deployment projects of the Chinese Academy of Sciences. It was published online on Nature-Communications on February 16 (Nature Communications , 8:14486, DOI: 10.1038/ncomms14486, 2017).
Shenyang Institute of Materials Science Shenyang (China) Laboratory of Solid Atomic Image Science Ma Xiuliang Research Group, Suning University Xu Ningsheng Research Group and Zhejiang University Jin Chuanhong Research Group researchers also participated in the study.
(Original title: Progress in research on control of crystalline domain size and electrical and thermal properties of graphene)
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