Department of Mechanical Engineering and the Materials Science and Engineering Program, The University of Texas at Austin, Austin, Texas 78712, USA.
ACS Nano. 2011 Sep 27;5(9):6916-24. doi: 10.1021/nn201207c. Epub 2011 Sep 6.
Reproducible dry and wet transfer techniques were developed to improve the transfer of large-area monolayer graphene grown on copper foils by chemical vapor deposition (CVD). The techniques reported here allow transfer onto three different classes of substrates: substrates covered with shallow depressions, perforated substrates, and flat substrates. A novel dry transfer technique was used to make graphene-sealed microchambers without trapping liquid inside. The dry transfer technique utilizes a polydimethylsiloxane frame that attaches to the poly(methyl methacrylate) spun over the graphene film, and the monolayer graphene was transferred onto shallow depressions with 300 nm depth. The improved wet transfer onto perforated substrates with 2.7 μm diameter holes yields 98% coverage of holes covered with continuous films, allowing the ready use of Raman spectroscopy and transmission electron microscopy to study the intrinsic properties of CVD-grown monolayer graphene. Additionally, monolayer graphene transferred onto flat substrates has fewer cracks and tears, as well as lower sheet resistance than previous transfer techniques. Monolayer graphene films transferred onto glass had a sheet resistance of ∼980 Ω/sq and a transmittance of 97.6%. These transfer techniques open up possibilities for the fabrication of various graphene devices with unique configurations and enhanced performance.
为了改善通过化学气相沉积（CVD）生长在铜箔上的大面积单层石墨烯的转移，开发了可重复的干燥和湿润转移技术。这里报道的技术允许转移到三类不同的衬底上：具有浅凹陷的衬底、穿孔衬底和平坦衬底。一种新的干燥转移技术被用来制造没有捕获内部液体的石墨烯密封微腔。干燥转移技术利用一种与聚甲基丙烯酸甲酯（PMMA）相连的聚二甲基硅氧烷（PDMS）框架，将单层石墨烯转移到具有 300nm 深度的浅凹陷中。改进后的湿润转移到具有 2.7μm 直径孔的穿孔衬底上，可以实现 98%的孔覆盖率，覆盖连续薄膜，允许使用拉曼光谱和透射电子显微镜来研究 CVD 生长的单层石墨烯的固有性质。此外，转移到平坦衬底上的单层石墨烯比以前的转移技术具有更少的裂纹和撕裂，以及更低的面电阻。转移到玻璃上的单层石墨烯薄膜的面电阻约为 980Ω/sq，透过率为 97.6%。这些转移技术为制造具有独特结构和增强性能的各种石墨烯器件开辟了可能性。
