采用水基原子层沉积工艺在石墨烯上沉积Al2O3介质薄膜研究

采用水基原子层沉积(H2O-based ALD)方法在石墨烯上直接生长Al2O3介质薄膜,研究了Al2O3成核机理.原子力显微镜(AFM)对Al2O3薄膜微观形态分析表明,沉积温度决定着Al2O3在石墨烯表面的成核生长情况,物理吸附在石墨烯表面的水分子是Al2O3成核的关键,物理吸附水分子的均匀性直接影响Al2O3薄膜的均匀性.在适当的温度窗口(100～130℃),Al2O3可以均匀沉积在石墨烯上,AFM测得Al2O3薄膜表面均方根粗糙度(RMS)为0.26 nm,X射线光电子能谱(XPS)表面分析与元素深度剖析表明,120℃下在石墨烯表面沉积的Al2O3薄膜中O和Al元素的含量比约为1.5.拉曼光谱分析表明,采用H2O-based ALD工艺沉积栅介质薄膜不会降低石墨烯晶体质量.

Studies on H2O-based Atomic Layer Deposition of Al2O3 Dielectric on Pristine Graphene

Al2O3 films were deposited directly onto the surface of graphene by H2O-based atomic layer deposition(ALD) method,where physically absorbed water molecules acted as oxidant and the growing temperature changed from 60℃ to 260℃.The morphology of Al2O3 films was characterized by atomic force microscope(AFM).AFM images revealed that the distribution of physically adsorbed H2O molecules on the surface of graphene decided the morphology of Al2O3 film,and conformal and uniform Al2O3 film was achieved with the root mean square(RMS) roughness of 0.26 nm when the growing temperature was around 100 130℃.X-ray photoelectron spectroscopy(XPS) analysis showed that the O/Al ratio was close to stoichiometric condition of 1.5.Raman spectroscopy analysis revealed that H2O-based ALD process did not destroy the structure of graphene.The growing temperature in the H2O-based ALD process had significant impact on the initial nucleation and the growth of Al2O3 films.