Abstract
Chemical vapour deposition (CVD) growth of graphene has attracted much attention, aiming at the mass production of large-area and high-quality specimens. To optimize the growth condition, CVD grown graphene is conventionally characterized after synthesis. Real-time observation during graphene growth enables us to understand the growth mechanism and control the growth more easily. Here we report the optical microscope observation of the CVD growth of graphene in real time by focusing the radiation emitted from the growing graphene, which we call 'radiation-mode optical microscopy'. We observe the growth and shrinkage of graphene in response to the switching on and off of the methane supply. Analysis of the growth feature reveals that the attachment and detachment of carbon precursors are the rate-determining factor in the CVD growth of graphene. We expect radiation-mode optical microscopy to be applicable to the other crystal growth at high temperatures in various atmospheres.
Highlights
Chemical vapour deposition (CVD) growth of graphene has attracted much attention, aiming at the mass production of large-area and high-quality specimens
Since the sufficient contrast can be obtained at the temperatures characteristic of the CVD growth of graphene on Cu from CH4, we evaluate the nucleation density, growth rate and shrinkage rate of graphene
Optical measurements can be performed under high temperature and high pressure conditions in which graphene grows on Cu
Summary
Chemical vapour deposition (CVD) growth of graphene has attracted much attention, aiming at the mass production of large-area and high-quality specimens. We report the optical microscope observation of the CVD growth of graphene in real time by focusing the radiation emitted from the growing graphene, which we call ‘radiation-mode optical microscopy’. If the CVD process is observed in real time, it helps the optimization of parameters and the elucidation of the growth mechanism. We report a radiation-mode optical microscopy (Rad-OM) for in situ and real-time observation on the CVD growth of graphene on Cu from CH4. At the high temperatures at which graphene grows by CVD, the material emits radiation light even in the visible light region[30] depending on its emissivity. It is known that the emissivity strongly depends on the flatness, chemical state of the surface and so on, the Cu substrate is flattened and reduced by the exposure to the chemically reductive molecules such as H2 and CH4 at high temperatures before and during the growth.
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