Process Pathway Controlled Evolution of Phase and Van-der-Waals Epitaxy in In/In<sub>2</sub>O<sub>3</sub>on Graphene Heterostructures

Kenan Elibol, Clemens Mangler, Tushar Gupta, Georg Zagler, Dominik Eder, Jannik C. Meyer, Jani Kotakoski, Bernhard C. Bayer

Many applications of 2D materials require deposition of non-2D metals and metal-oxides onto the 2D materials. Little is however known about the mechanisms of such non-2D/2D interfacing, particularly at the atomic scale. Here, atomically resolved scanning transmission electron microscopy (STEM) is used to follow the entire physical vapor deposition (PVD) cycle of application-relevant non-2D In/In(2)O(3)nanostructures on graphene. First, a "quasi-in-situ" approach with indium being in situ evaporated onto graphene in oxygen-/water-free ultra-high-vacuum (UHV) is employed, followed by STEM imaging without vacuum break and then repeated controlled ambient air exposures and reloading into STEM. This allows stepwise monitoring of the oxidation of specific In particles toward In(2)O(3)on graphene. This is then compared with conventional, scalable ex situ In PVD onto graphene in high vacuum (HV) with significant residual oxygen/water traces. The data shows that the process pathway difference of oxygen/water feeding between UHV/ambient and HV fabrication drastically impacts not only non-2D In/In(2)O(3)phase evolution but also In2O3/graphene out-of-plane texture and in-plane rotational van-der-Waals epitaxy. Since non-2D/2D heterostructures' properties are intimately linked to their structure and since influences like oxygen/water traces are often hard to control in scalable fabrication, this is a key finding for non-2D/2D integration process design.

Physics of Nanostructured Materials
External organisation(s)
Technische Universität Wien
Advanced Functional Materials
No. of pages
Publication date
Peer reviewed
Austrian Fields of Science 2012
103042 Electron microscopy, 104011 Materials chemistry, 103018 Materials physics
ASJC Scopus subject areas
Condensed Matter Physics, Chemistry(all), Materials Science(all)
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