title: Controlled direct growth of Al2O3-doped HfO2 films on graphene by H2O-based atomic layer deposition.
abstract: Graphene has been drawing worldwide attention since its discovery in 2004. In order to realize graphene-based devices, thin, uniform-coverage and pinhole-free dielectric films with high permittivity on top of graphene are required. Here we report the direct growth of Al2O3-doped HfO2 films onto graphene by H2O-based atom layer deposition (ALD). Al2O3-onto-HfO2 stacks benefited the doping of Al2O3 into HfO2 matrices more than HfO2-onto-Al2O3 stacks did due to the micro-molecular property of Al2O3 and the high chemical activity of trimethylaluminum (TMA). Al2O3 acted as a network modifier, maintained the amorphous structure of the film even to 800 °C, and made the film smooth with a root mean square (RMS) roughness of 0.8 nm, comparable to the surface of pristine graphene. The capacitance and the relative permittivity of Al2O3-onto-HfO2 stacks were up to 1.18 μF cm(-2) and 12, respectively, indicating the high quality of Al2O3-doped HfO2 films on graphene. Moreover, the growth process of Al2O3-doped HfO2 films introduced no detective defects into graphene confirmed by Raman measurements.
authors.affiliation: State Key Laboratory of Functional Materials for Informatics, Institute of Microsystem and Information Technology, Chinese Academy of Sciences, Changning Road 865, Shanghai 200050, P. R. China. xh_cheng@mail.sim.ac.cn.
authors.forename: Li
authors.initials: L
authors.lastname: Zheng
authors.forename: Xinhong
authors.initials: X
authors.lastname: Cheng
authors.forename: Yuehui
authors.initials: Y
authors.lastname: Yu
authors.forename: Yahong
authors.initials: Y
authors.lastname: Xie
authors.forename: Xiaolong
authors.initials: X
authors.lastname: Li
authors.forename: Zhongjian
authors.initials: Z
authors.lastname: Wang