High-quality bilayer graphene grown on softened copper foils by atmospheric pressure chemical vapor deposition

常压化学气相沉积法在软化铜箔上生长高质量双层石墨烯

Bilayer graphene(BLG)shows great application prospect and potential in next-generation electronics because of its unique electrical and mechanical properties.However,the scalable synthesis of large-area high-quality BLG films is still a great challenge,despite the maturity of chemical vapor deposition(CVD)technique.In this study,we report a robust method to grow BLGs on flat,softened Cu foils by atmospheric pressure CVD.A moderate amount of residual oxygen accelerates the growth of BLG domains while suppressing the formation of multilayers.Raising the nucleation density at low hydrogen pressure efficiently increases the film continuity.Based on the optimized CVD process,the growth of graphene films on 4×4 cm^2 Cu foils with an average BLG coverage of 76%is achieved.The morphology and structure characterizations demonstrate a high quality of the BLG.Dual gate field-effect transistors are investigated based on AB-stacked BLG,with a tunable bandgap and high carrier mobility of up to 6790 cm2 V^−1 s^−1 at room temperature.

双层石墨烯因其独特的物理性质在新型电子器件等领域具有广阔的应用前景.大面积高质量双层石墨烯的批量化制备是实现其后续应用的关键.目前,基于铜表面自限制催化的化学气相沉积法可有效实现单层石墨烯的生长,但由于第二层石墨烯结构导致更复杂的生长过程,双层石墨烯的可控制备极具挑战性.本文系统研究了石墨烯的常压化学气相沉积制备过程,提出了一种在软化铜箔基底上生长高质量双层石墨烯的方法.铜箔在随炉升温过程中软化并贴合至背面的石英舟/管表面,形成具有差异反应条件的铜箔双面,从而促使双层石墨烯在其正面生长.反应系统中的残余氧气有效加快了双层石墨烯的生长.同时,适量的残余氧气可抑制三层及少数层石墨烯的形成,提高双层石墨烯产物的均匀性.基于优化的生长条件,在4×4 cm^2铜箔上实现了双层覆盖率达76%的高质量石墨烯薄膜的生长.基于AB堆垛双层石墨烯的双栅场效应晶体管,室温载流子迁移率达6790 cm2 V^−1 s^−1.本研究有助于推动石墨烯等二维材料的层数可控合成技术的发展.