Atomic Structures and Doping Effects in Intercalated Few-layer Graphene

Intercalation, the process of inserting atoms or molecules into host materials, has been extensively researched in graphite for energy storage and reaction catalysis applications. The recent ability to isolate graphite with controlled number of carbon layers has also led to a surge of interest in intercalated few-layer graphene (FLG) and bilayer graphene (BLG). Few-layer graphene intercalated with either single atomic species or molecules has been used to explore the physics of graphene with large numbers of free charge carriers (high doping) and for potential applications in next-generation battery electrode and flexible transparent conductors. The atomic structures, and the resulting doping effects those structures, in intercalation compounds are a key part of predicting the properties and applications of these materials. However, most of the data for atomic structures of intercalation compounds have been by x-ray diffraction, Raman spectroscopy, and other spatially averaged techniques. These techniques do not directly provide information about local atomic structures of intercalants. In this dissertation, we describe methods of fabricating intercalated FLG to be studied with aberration-correct scanning transmission electron microscopy, and we present atomic-resolution images of BLG and FLG intercalated with FeCl3. In BLG we discover two distinct intercalated structures that we identify as monolayer-FeClIntercalation, the process of inserting atoms or molecules into host materials, has been extensively researched in graphite for energy storage and reaction catalysis applications. The recent ability to isolate graphite with controlled number of carbon layers has also led to a surge of interest in intercalated few-layer graphene (FLG) and bilayer graphene (BLG). Few-layer graphene intercalated with either single atomic species or molecules has been used to explore the physics of graphene with large numbers of free charge carriers (high doping) and for potential applications in next-generation battery electrode and flexible transparent conductors. The atomic structures, and the resulting doping effects those structures, in intercalation compounds are a key part of predicting the properties and applications of these materials. However, most of the data for atomic structures of intercalation compounds have been by x-ray diffraction, Raman spectroscopy, and other spatially averaged techniques. These techniques do not directly provide information about local at