石墨烯
材料科学
成核
范德瓦尔斯力
分子束外延
拉曼光谱
外延
纳米技术
异质结
氮化硼
光电子学
化学
图层(电子)
光学
有机化学
分子
物理
作者
Martin Heilmann,Muhammad Y. Bashouti,A. Yu. Egorov,J. M. J. Lopes
出处
期刊:2D materials
[IOP Publishing]
日期:2018-01-15
卷期号:5 (2): 025004-025004
被引量:27
标识
DOI:10.1088/2053-1583/aaa4cb
摘要
Van der Waals heterostructures comprising of hexagonal boron nitride and graphene are promising building blocks for novel two-dimensional devices such as atomically thin transistors or capacitors. However, demonstrators of those devices have been so far mostly fabricated by mechanical assembly, a non-scalable and time-consuming method, where transfer processes can contaminate the surfaces. Here, we investigate a direct growth process for the fabrication of insulating hexagonal boron nitride on high quality epitaxial graphene using plasma assisted molecular beam epitaxy. Samples were grown at varying temperatures and times and studied using atomic force microscopy, revealing a growth process limited by desorption at high temperatures. Nucleation was mostly commencing from morphological defects in epitaxial graphene, such as step edges or wrinkles. Raman spectroscopy combined with x-ray photoelectron measurements confirm the formation of hexagonal boron nitride and prove the resilience of graphene against the nitrogen plasma used during the growth process. The electrical properties and defects in the heterostructures were studied with high lateral resolution by tunneling current and Kelvin probe force measurements. This correlated approach revealed a nucleation apart from morphological defects in epitaxial graphene, which is mediated by point defects. The presented results help understanding the nucleation and growth behavior during van der Waals epitaxy of 2D materials, and point out a route for a scalable production of van der Waals heterostructures.
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