基于抛光基材的热蒸镀铜箔生长高平整单层石墨烯薄膜

在石墨烯的化学气相沉积工艺中,铜箔是决定石墨烯薄膜质量的重要因素。传统铜箔由于制备工艺的限制,存在大量的缺陷,导致石墨烯薄膜的成核密度较高。本工作选用抛光铝板、抛光不锈钢板、微晶玻璃和SiO₂/Si作为基材,用热蒸镀法制备了不同粗糙度的铜箔,并详细讨论了以该系列铜箔生长高平整度石墨烯薄膜的条件及铜箔对石墨烯薄膜品质的影响。实验结果表明,铜箔以(111)取向为主,与基材分离后,表面具有纳米级平整度。在生长石墨烯后,从SiO₂/Si剥离的铜箔成核密度是4种基材中最小的。同时,从SiO₂/Si剥离的铜箔晶体结构变化最不明显,具有良好的结晶性,表面几乎不存在铜晶界缺陷。当压强为3 000 Pa,氢气和甲烷流速分别为300 mL/min和0.5 mL/min时,可以获得约1 mm横向尺寸的石墨烯单晶晶畴。

High Flatness Single Layer Graphene Film Grown on Thermal Evaporation Cu Foils Based on Polished Substrate

Cu foils play an important role in preparing high quality of graphene films by chemical vapor deposition. For the commonly used commercial Cu foil, the nucleation density of graphene is high due to the associated defects in the manufacturing process of Cu foil. In this work, different substrates containing polished aluminum plate, polished stainless steel plate, glass ceramics, and SiO₂/Si were selected as substrates to prepare distinct Cu foils with different roughness by thermal evaporation method. Then the growth conditions of high flatness graphene films and the effect of Cu foils on graphene films were discussed in detail. The results show that Cu foils are predominantly (111) orientation, and keep the surface with nanometer-level flatness after separation from substrates. After the growth of graphene, the nucleation density of Cu foil peeled from SiO₂/Si is the lowest among these four kinds of substrates. At the same time, its crystal structure has almost no change and has good crystallinity. There are nearly no Cu grain boundary defects on the surface of the Cu foil peeled from SiO₂/Si. When the pressure is 3 000 Pa and the flow rates of hydrogen and methane are 300 mL/min and 0.5 mL/min, respectively, a graphene single crystal domain with a lateral dimension of about 1 mm can be obtained.