Chaliyawala Harsh A, Rajaram Narasimman, Patel Roma, Ray Abhijit, Mukhopadhyay Indrajit
Solar Research and Development Center, Department of Solar Energy, Pandit Deendayal Petroleum University, Raisan, Gandhinagar, 382007 Gujarat, India.
Material Science and Technology Division, CSIR-National Institute for Interdisciplinary Science and Technology, Thiruvananthapuram, 695019 Kerela, India.
ACS Omega. 2019 May 23;4(5):8758-8766. doi: 10.1021/acsomega.9b00051. eCollection 2019 May 31.
Camphor-based mono-/bilayer graphene (MLG) sheets have been synthesized by very facile atmospheric chemical vapor deposition processes on Si/SiO, soda lime glass, and flexible polyethylene terephthalate films. The effect of camphor concentration with respect to distance between camphor and the Cu foil () has been varied to investigate the controlled formation of a homogeneous graphene sheet over a large area on Cu foil. Raman studies show a remarkable effect of camphor at a typical distance () to form a monolayer to multilayer graphene (MULG) sheet. The signature of MLG to MULG sheets appears due to increase in the number of nucleation sites, even over the subsequent domains that contribute stacks of graphene over each other as observed by high-resolution transmission electron microscopy images. Moreover, the increase in camphor concentration at a particular distance generates more defect states in graphene as denoted by D band at 1360 cm. Uniform distribution of large-area MLG demonstrates an intense 2D/G ratio of ∼2.3. Electrical and optical measurements show a sheet resistance of ∼1 kΩ/sq with a maximum transmittance of ∼88% at 550 nm for low camphor concentration. An improvement in the rectification and photodiode behavior is observed from the diodes fabricated on n-Si/MULG as compared to n-Si/MLG in dark and light conditions.
基于樟脑的单层/双层石墨烯（MLG）片材已通过非常简便的常压化学气相沉积工艺在硅/二氧化硅、钠钙玻璃和柔性聚对苯二甲酸乙二酯薄膜上合成。已改变樟脑浓度相对于樟脑与铜箔之间距离（）的影响，以研究在铜箔上大面积均匀形成石墨烯片材的可控过程。拉曼研究表明，在典型距离（）下，樟脑对形成单层至多层石墨烯（MULG）片材有显著影响。由于成核位点数量增加，出现了从MLG到MULG片材的特征，即使在后续区域也是如此，如高分辨率透射电子显微镜图像所示，这些区域相互堆叠形成石墨烯。此外，在特定距离下樟脑浓度的增加会在石墨烯中产生更多缺陷态，如1360 cm处的D带所示。大面积MLG的均匀分布表明其2D/G比约为2.3。电学和光学测量表明，对于低樟脑浓度，薄膜电阻约为1 kΩ/sq，在550 nm处的最大透过率约为88%。与黑暗和光照条件下的n-Si/MLG相比，在n-Si/MULG上制备的二极管的整流和光电二极管行为有所改善。
