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CVD growth2010Cross-sectional transmission electron microscopy of thin graphite films grown by chemical vapor deposition.Robert Colby, Qingkai Yu, Helin Cao, Steven S. Pei, Eric A. Stach, and Yong P. ChenDiamond and Related Materials Volume 19, Issues 2-3, February-March 2010, Pages 143-146
Graphene has been the subject of an extraordinary upsurge of interest due to its intriguing properties and potential applications. Recent work has shown that excellent electronic properties are exhibited by large-scale ultrathin graphite films, grown by chemical vapor deposition on a polycrystalline metal and transferred to a device-compatible surface. The properties of such multilayered graphene films could depend strongly on film thickness and uniformity. Unlike the other common methods for analysis in the literature, cross-sectional transmission electron microscopy (TEM) would provide direct, straightforward analysis of film thickness and quality, as well as provide a means to investigate specific defect structures (e.g. wrinkles). However, this approach has not often been pursued due to the sensitivity of graphite to the electron and ion beam damage in such a procedure. Here, an approach to creating cross-sectional TEM samples using a focused ion beam lift-out method is presented, along with the resulting TEM images of thin graphite films and several wrinkle defects. Samples removed from as-grown films on polycrystalline nickel and films removed from measured devices are presented. The benefits and limitations to this approach are discussed.
Scalable growth of free-standing graphene wafers with copper(Cu) catalyst on SiO2/Si substrate: Thermal conductivity of the wafersYun-Hi Lee and Jong-Hee LeeAppl. Phys. Lett. 96, 083101 (2010)
The authors report scalable growth of free-standing graphene wafers with copper(Cu) catalyst on SiO2/Si substrate at low temperature and investigation of their thermal conductivity. The Cu is the most common and the cheapest catalyst among electronic materials. Our process for producing the graphene with the Cu is based on a low-pressure, fast-heating chemical vapor deposition method. Thermal conductivity measurements with nondestructive Raman spectroscopy showed that the free-standing-graphene is a good thermal conductor. The possibility of growing graphene wafer at low temperatures by using a Cu thin film should accelerate research and facilitate the development of graphene for practical applications.
Wafer-Scale Synthesis and Transfer of Graphene FilmsNano Lett., 2010, 10 (2), pp 490–493
Youngbin Lee, Sukang Bae, Houk Jang, Sukjae Jang, Shou-En Zhu, Sung Hyun Sim, Young Il Song, Byung Hee Hong and Jong-Hyun Ahn
2009Transfer of Large-Area Graphene Films for High-Performance Transparent Conductive ElectrodesNano Lett., 2009, 9 (12), pp 4359–4363
Xuesong Li, Yanwu Zhu, Weiwei Cai, Mark Borysiak, Boyang Han, David Chen, Richard D. Piner, Luigi Colombo and Rodney S. Ruoff
Chemical vapor deposition of large area few layer graphene on Si catalyzed with nickel filmsThin Solid Films Volume 518, Issue 6, Supplement 1, 1 January 2010, Pages S128-S132
Wei Liu, Choong-Heui Chung, Cong-Qin Miao, Yan-Jie Wang, Bi-Yun Li, Ling-Yan Ruana Ketan Patel, Young-Ju Park, Jason Woob and Ya-Hong Xie
We present the results of a systematic study of chemical vapor deposition of graphene on silicon substrates. The silicon substrate is covered with SiO2 and capped with an electron-beam evaporator deposited nickel film, which serves as the catalyst for carbon precursor decomposition. Methane is used as the carbon precursor. Three key parameters of CVD growths, the growth temperature, time, and the post-growth cooling rate are studied and the optimized combination of the three allowed for the reproducible fabrication of single layer graphene of larger than 100 ?m2 covering more than 50% of the surface of 1-in. diameter Si wafers. We further demonstrate the transfer of CVD graphene onto SiO2/Si surfaces with higher than 95% success rate. Our result together with those reported by other research groups shows real promise of the integration of carbon electronics with silicon integrated circuit technology. Synthesis, Transfer, and Devices of Single- and Few-Layer Graphene byChemical Vapor Deposition
Lewis Gomez De Arco, Yi Zhang, Akshay Kumar, and Chongwu Zhou
The advance of graphene-based nanoelectronics hasbeen hampered due to the difficulty in producing single- or few-layer graphene over large areas. We report a simple, scalable, andcost-efficient method to prepare graphene using methane-basedCVD on nickel films deposited over complete Si/SiO2 wafers. Byusing highly diluted methane, single- and few-layer graphene wereobtained, as confirmed by micro-Raman spectroscopy. In addition,a transfer technique has been applied to transfer the graphene filmto target substrates via nickel etching. FETs based on the graphenefilms transferred to Si/SiO2 substrates revealed a weak p-type gatedependence, while transferring of the graphene films to glass sub-strate allowed its characterization as transparent conductive films,exhibiting transmittance of 80% in the visible wavelength range
Large Area, Few-Layer Graphene Films on Arbitrary Substrates by Chemical Vapor DepositionNano Lett., 2009, 9 (1), pp 30–35
Alfonso Reina, Xiaoting Jia, John Ho, Daniel Nezich, Hyungbin Son, Vladimir Bulovic, Mildred S. Dresselhaus and Jing Kong
Large-scale pattern growth of graphene films for stretchable transparent electrodesNature 457, 706-710 (5 February 2009)
Keun Soo Kim, Yue Zhao, Houk Jang, Sang Yoon Lee, Jong Min Kim, Kwang S. Kim, Jong-Hyun Ahn, Philip Kim, Jae-Young Choi & Byung Hee Hong
Problems associated with large-scale pattern growth of graphene constitute one of the main obstacles to using this material in device applications. Recently, macroscopic-scale graphene films were prepared by two-dimensional assembly of graphene sheets chemically derived from graphite crystals and graphene oxides. However, the sheet resistance of these films was found to be much larger than theoretically expected values. Here we report the direct synthesis of large-scale graphene films using chemical vapour deposition on thin nickel layers, and present two different methods of patterning the films and transferring them to arbitrary substrates. The transferred graphene films show very low sheet resistance of 280 per square, with 80 per cent optical transparency. At low temperatures, the monolayers transferred to silicon dioxide substrates show electron mobility greater than 3,700 cm2 V-1 s-1 and exhibit the half-integer quantum Hall effect, implying that the quality of graphene grown by chemical vapour deposition is as high as mechanically cleaved graphene6. Employing the outstanding mechanical properties of graphene7, we also demonstrate the macroscopic use of these highly conducting and transparent electrodes in flexible, stretchable, foldable electronics Large-Area Synthesis of High-Quality and Uniform Graphene Films on Copper FoilsScience,Vol. 324. pp. 1312 - 1314 (5 June 2009)
Xuesong Li, Weiwei Cai, Jinho An, Seyoung Kim, Junghyo Nah, Dongxing Yang, Richard Piner, Aruna Velamakanni, Inhwa Jung, Emanuel Tutuc, Sanjay K. Banerjee, Luigi Colombo, Rodney S. Ruoff
Graphene has been attracting great interest because of its distinctive band structure and physical properties. Today, graphene is limited to small sizes because it is produced mostly by exfoliating graphite. We grew large-area graphene films of the order of centimeters on copper substrates by chemical vapor deposition using methane. The films are predominantly single-layer graphene, with a small percentage (less than 5%) of the area having few layers, and are continuous across copper surface steps and grain boundaries. The low solubility of carbon in copper appears to help make this growth process self-limiting. We also developed graphene film transfer processes to arbitrary substrates, and dual-gated field-effect transistors fabricated on silicon/silicon dioxide substrates showed electron mobilities as high as 4050 square centimeters per volt per second at room temperature. Graphene segregated on Ni surfaces and transferred to insulatorsAppl. Phys. Lett. 93, 113103 (2008)
Qingkai Yu, Jie Lian, Sujitra Siriponglert, Hao Li, Yong P. Chen and Shin-Shem Pei
We report an approach to synthesize high quality graphene by surface segregation and substrate transfer. Graphene was segregated from Ni surface under the ambient pressure by dissolving carbon in Ni at high temperatures followed by cooling down with various rates. Different cooling rates led to different segregation behaviors, strongly affecting the thickness and quality of the graphene films. Electron microscopy and Raman spectroscopy indicated that the graphene films synthesized with medium cooling rates have high quality crystalline structure and well-controlled thicknesses. The graphene films were transferred to insulating substrates by wet etching and found to maintain their high quality. |