Investigation of the cleanliness of transferred graphene: The first step toward its application as a window material for electron microscopy and spectroscopy

Abstract

The cleanliness of transferred graphene is of significant importance for its application as the window material in environmental cells used for electron microscopy and spectroscopy. We investigated the dependence of the cleanliness of graphene on transfer routes, including FeCl 3 etching, (NH 4) 2 S 2 O 8 etching, electrochemical delamination, and O 2 - bubbling, by means of transmission electron microscopy and X-ray photoelectron spectroscopy. It was found that electrochemical delamination provided the cleanest graphene with only a small amount of poly(methyl methacrylate) (PMMA) residue existing on the surface.