高温退火Cu(111)衬底上生长高质量厘米尺寸单晶石墨烯

Growth of High-Quality Centimeter-Size Single-Crystal Graphene on High-Temperature Annealed Cu(111)Substrate

二维(2D)石墨烯具有原子层厚度,在电子器件中展示出突破摩尔定律限制的巨大潜力。目前,化学气相沉积(CVD)是一种广泛应用于石墨烯生长的方法,满足低成本、大面积生产和易于控制层数的需求。然而,由于催化金属(例如Cu)衬底一般为多晶特性,导致CVD法生长的石墨烯晶体质量相对较差。为此,通过高温退火工艺制备了Cu(111)单晶衬底,使石墨烯的初始成核过程得到了很好的控制,从而实现了厘米尺寸的高质量单晶石墨烯的制备。根据二者的晶格匹配关系,Cu(111)衬底为石墨烯生长提供了唯一的成核取向,相邻石墨烯成核岛的边界能够缝合到一起。单晶石墨烯具有高电导率,相较于原始多晶Cu上生长的石墨烯(1415.7Ω·sq^(-1)),其平均薄层电阻低至607.5Ω·sq^(-1)。高温退火能够清洁铜箔,从而获得表面粗糙度较低的洁净石墨烯。将石墨烯用于场效应晶体管(FET),器件的最大开关比为145.5,载流子迁移率为2.31×10^(3)cm^(2)·V^(-1)·s^(-1)。基于以上结果,相信本工作中的单晶石墨烯还满足其他高性能电子器件的制备。

Two-dimensional(2D)graphene has shown great potential of breakthrough of Moore’s law limitation due to its atomic thickness in electronic devices.Up to now,chemical vapor deposition(CVD)is a widely applied method for graphene growth due to its low-cost,large-area production,and easy control in layer number.However,the CVD-grown graphene usually suffers from relatively low quality derived from the polycrystalline nature of catalytic metal(e.g.,Cu)substrates.Herein,single-crystal Cu(111)substrates were fabricated by a high-temperature annealing process,initial nucleation of graphene on it has been well controlled,and high-quality and centimeter-size single-crystal graphene was achieved.The Cu(111)substrate provides onefold orientation for the graphene growth according to their lattice matching relation,and domain boundaries of neighboring graphene nuclei could stitch together.The as-grown single-crystal graphene has an average sheet resistance of 607.5Ω·sq^(-1).Compared to that of grown on the pristine polycrystalline Cu(1415.7Ω·sq^(-1)),it shows high electrical conductivity.High-temperature annealing purified the Cu foils,and induced a clean graphene surface with lower roughness.The quality of graphene is further verified by using it in a field-effect transistor(FET),resulting in a maximum switch ratio of 145.5 and carrier mobility of 2.31×10^(3)cm^(2)·V^(-1)·s^(-1).Based on these results,we believe that the single-crystal graphene in present work is also feasible for fabricating other high-performance electronic devices.