Fig. 1. Schematic of direct and indirect transfer of graphene石墨烯直接转移与间接转移示意图

Fig. 2. Schematics of various transfer methods: (a) “R2R” transfer^[19]; (b) electrochemical delamination transfer^[20]; (c) mechanical delamination transfer^[22]; (d) direct transfer by dissolving the substrate^[25]. 各种转移方法示意图　(a) “卷对卷”转移^[19]; (b)电化学分离转移^[20]; (c)机械剥离转移^[22]; (d)溶解基底的直接转移^[25]

Fig. 3. AFM images and normalized height distribution profiles of transferred graphene using PMMA with different average molecular weight: (a), (e) 996000; (b), (f) 350000; (c), (g) 35000; (d), (h) 15000^[35]. The curves above each AFM image represent the line profile of the white slanting line in the images. The size of AFM surface image is 5 μm × 5 μm. 不同平均分子量PMMA转移的石墨烯的AFM图和归一化高度分布图^[35], 其中对应PMMA的平均分子量为: (a), (e) 996000; (b), (f) 350000; (c), (g) 35000; (d), (h) 15000; AFM图像上方的曲线是AFM图像中白色斜线的线扫描, AFM图像尺寸为5 μm × 5 μm

Fig. 4. The interactions between polymers and graphene^[40]: (a) van der Waals force; (b) — interactions; (c) electrostatic interactions; (d) chemical bonding. 石墨烯与聚合物的相互作用力示意图^[40] 　(a) 范德瓦耳斯力; (b) — 键; (c)静电力; (d)化学键

Fig. 5. Indirect graphene transfer with “modified RCA clean”^[29]: (a) Transfer process flow; optical microscopy images and scanning electron microscopy images of (b), (c) traditional transferred graphene film and (d), (e) modified RCA cleaning transferred graphene film. In (b) and (c) the metal residues and the small holes are marked with blue circles and yellow circles, respectively, and the graphene adlayers (with darker contrast) are marked with arrows. The arrow in (e) points to the wrinkles (the dark lines). 结合硅晶圆清洗技术的间接转移^[29] 　(a)采用改进的石墨烯清洗方法的转移流程; (b), (c)传统转移和(d), (e)改进的石墨烯清洗转移的光学图像和扫描电子显微镜图像; (b)和(c)中金属微粒残留用蓝色圆圈标记, 小破洞用黄色圆圈标记, 多层石墨烯区域（对比度较暗）用箭头标记; （e）中箭头标记的窄的黑色线条为褶皱

Fig. 6. Schematic of graphene transfer with NH₄OH and H₂O₂^[49]使用NH₄OH+H₂O₂转移石墨烯流程图^[49]

Fig. 7. Schematic showing the steps of graphene transfer with hot deionized (DI) water^[50]. 热去离子水浸湿-剥离石墨烯转移流程图^[50]

Fig. 8. TEM images of graphene after air and H₂/Ar two-step annealing at 250 ℃ for 2 h^[57]. Panels (a) and (b) show the details of surface cleanliness. The same images are duplicated and colored in the lower panels to distinguish the PMMA residues that decomposed differently. The areas free of PMMA are shown in gray in the colored images. The bottom-left image interprets the meaning of different colors, in which blue, red, and yellow stand for PMMA-G, PMMA-A, and Cu nanoparticles, respectively. (c) Atomic resolution of graphene clean surface with PMMA residue shown piecewise at the bottom corner after annealing. 石墨烯在空气和H₂/Ar 200 ℃退火2 h后的TEM图像^[57] 　(a), (b)显示表面清洁度的细节, 下面对应面板中复制的着色的图像用以区分分解温度不同的PMMA残留物, 没有PMMA的区域在彩色图像中显示为灰色; 左下角的图解释了相应的颜色, 其中蓝色、红色和黄色分别代表PMMA-G, PMMA-A和Cu纳米颗粒; (c)图(b)中所示区域的TEM高分辨图, 显示仍有PMMA残留物

Fig. 9. Carrier layer materials for indirect transfer of graphene.用于石墨烯间接转移的中介层材料

Fig. 10. (a)−(c) Optical and (d)−(f) three-dimensional AFM images showing the surface morphologies of the monolayer graphene films transferred onto SiO₂/Si substrates by TRT, PMMA and PET/silicone, respectively^[68]. TRT, PMMA, PET/Silicone作为中介层转移结果的对比^[68] 　(a)−(c)光学显微图像; (d)−(f)三维AFM图像