arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 2005.05007cond-mat.mtrl-scicond-mat.mes-hall
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等离子体增强化学气相沉积法直接生长毫米级扭曲双层石墨烯

Direct growth of mm-size twisted bilayer graphene by plasma-enhanced chemical vapor deposition

Yen-Chun Chen, Wei-Hsiang Lin, Wei-Shiuan Tseng, Chien-Chang Chen, George. R. Rossman, Chii-Dong Chen, Yu-Shu Wu, Nai-Chang Yeh

摘要:

等离子体增强化学气相沉积(PECVD)技术已被证明是一种有效的方法,可以实现高质量单层石墨烯(MLG)的单步合成,而不需要主动加热。在这里,我们报告的PECVD生长的单晶六方双层石墨烯(BLG)的薄片和毫米大小的BLG薄膜的层间扭曲角控制的生长参数。扭转角已确定由三种实验方法,包括通过扫描电子显微镜,分析的扭转角依赖的拉曼光谱特性,并测量莫尔周期的两个堆叠的单分子膜之间的晶体边缘的相对取向的直接测量。在mm尺寸的扭曲BLG(tBLG)膜中,平均扭曲角可以控制在0至约20 \degree,并且对于给定生长条件的角展度可以限制为< 7 \degree。利用Kelvin探针力显微镜和紫外光电子能谱学证实了MLG和BLG的不同功函数。基于小角度tBLG样品的背栅场效应晶体管器件的电学测量显示,在300 K下具有高质量的电学特性,绝缘温度依赖性低至100 K。这种受控的PECVD生长的tBLG因此提供了一种有效的方法来研究不同的莫尔电位对tBLG的影响。

英文摘要:

Plasma enhanced chemical vapor deposition (PECVD) techniques have been shown to be an efficient method to achieve single-step synthesis of high-quality monolayer graphene (MLG) without the need of active heating. Here we report PECVD-growth of single-crystalline hexagonal bilayer graphene (BLG) flakes and mm-size BLG films with the interlayer twist angle controlled by the growth parameters. The twist angle has been determined by three experimental approaches, including direct measurement of the relative orientation of crystalline edges between two stacked monolayers by scanning electron microscopy, analysis of the twist angle-dependent Raman spectral characteristics, and measurement of the Moiré period with scanning tunneling microscopy. In mm-sized twisted BLG (tBLG) films, the average twist angle can be controlled from 0 to approximately 20 \degree, and the angular spread for a given growth condition can be limited to < 7 \degree. Different work functions between MLG and BLG have been verified by the Kelvin probe force microscopy and ultraviolet photoelectron spectroscopy. Electrical measurements of back-gated field-effect-transistor devices based on small-angle tBLG samples revealed high-quality electric characteristics at 300 K and insulating temperature dependence down to 100 K. This controlled PECVD-growth of tBLG thus provides an efficient approach to investigate the effect of varying Moiré potentials on tBLG.

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