Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, 72 Wenhua Road, Shenyang 110016, China.
State Key Laboratory of Optoelectronic Materials and Technologies, Guangdong Province Key Laboratory of Display Material and Technology, School of Physics and Engineering, Sun Yat-sen University, Guangzhou 510275, China.
Nat Commun. 2017 Feb 16;8:14486. doi: 10.1038/ncomms14486.
Understanding the influence of grain boundaries (GBs) on the electrical and thermal transport properties of graphene films is essentially important for electronic, optoelectronic and thermoelectric applications. Here we report a segregation-adsorption chemical vapour deposition method to grow well-stitched high-quality monolayer graphene films with a tunable uniform grain size from ∼200 nm to ∼1 μm, by using a Pt substrate with medium carbon solubility, which enables the determination of the scaling laws of thermal and electrical conductivities as a function of grain size. We found that the thermal conductivity of graphene films dramatically decreases with decreasing grain size by a small thermal boundary conductance of ∼3.8 × 10 W m K, while the electrical conductivity slowly decreases with an extraordinarily small GB transport gap of ∼0.01 eV and resistivity of ∼0.3 kΩ μm. Moreover, the changes in both the thermal and electrical conductivities with grain size change are greater than those of typical semiconducting thermoelectric materials.
了解晶界 (GBs) 对石墨烯薄膜的电输运和热输运性能的影响对于电子、光电和热电应用至关重要。在这里，我们报告了一种通过使用具有中等碳溶解度的 Pt 衬底的选择性吸附化学气相沉积方法，生长具有可调谐均匀晶粒尺寸（约 200nm 至约 1μm）的高质量、无缺陷单层石墨烯薄膜。这种方法能够确定热导率和电导率随晶粒尺寸变化的标度律。我们发现，随着晶粒尺寸的减小，石墨烯薄膜的热导率通过小的热边界电导（约 3.8×10^-3 W m^-1 K^-1）急剧降低，而电导率则以非常小的晶界输运间隙（约 0.01eV）和电阻率（约 0.3 kΩμm）缓慢降低。此外，热导率和电导率随晶粒尺寸变化的变化大于典型半导体热电材料的变化。
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