Ion‐Induced Defects in Graphite: A Combined Kelvin Probe and Raman Microscopy Investigation

Abstract

Carbon nanomaterials are important for future sensors and electronics. Defects determine the material properties, therefore, it is critical to find new ways to investigate defects at the nanoscale. In this context, Raman spectroscopy (RS) is the tool of choice to study defects in carbon nanomaterials. On the other hand, Kelvin probe force microscopy (KPFM) provides structural and surface potential information at the nanoscale. Here, the authors demonstrate the synergistic application of these methods in the investigation of ion-beaminduced defects in graphite. KPFM and RS imaging are used for visualizing ioninduced defects in a wide range of ion doses from 10 10 to 10 16 ions cm À2 . For the lower range of ion dose, the authors find that RS provides image contrast for the different defect regions in graphite up to a dose of 5 Â 10 13 ions cm À2 . For higher doses, the sp 2 carbon concentration becomes so small that the Raman spectra get dominated by broad amorphous carbon bands. For this dose range, the KPFM contrast allows the defective regions to be differentiated. This contrast in KPFM originates from sp 3 carbons that act as charge traps. The results show that KPFM and Raman microscopy make a powerful and necessary combination for studying the spatial distribution of defects in carbon.

Beyond graphene oxide: laser engineering functionalized graphene for flexible electronics

“…This was previously shown in a systematic analysis of defects made by focused ion beams on graphite showing also broad amorphous bands below 1000 cm À1 . 51 That amorphous signature is exactly what we observe in the case of GO films before laser irradiation (see Raman spectra in Fig. 5a), but not on Mod-G films even without laser irradiation.…”

Watching (De)Intercalation of 2D Metals in Epitaxial Graphene: Insight into the Role of Defects

“…The increase in surface potential, as shown in Figure 7c, could indicate the presence of intercalated gallium, [4] defective graphene, [37] or defective graphite. [38] These triangular features are also observed by PEEM (Figure 7e) and SEM on Gr/SiC with and without plasma treatment of the CHet process. Similar triangular and elongated motifs have been observed in SiC wafers and homoepitaxy of SiC, and they originate from basal plane dislocations, threading edge dislocations, and stacking faults from the SiC crystal.…”

Direct observation of bandgap opening at the metasurface of nano-scale highly oriented pyrolytic graphite

“…Moreover, the ion beam is the cause of the disordered structures (dominated by sp 3 ) that were observed by the Raman technique. The disorder structure depends on the density of ion dose, and the HOPG surface becomes amorphous at a high ion dose [36][37] . Additionally, the sp 3 defect can transform metallic into semiconducting in multilayer graphene 38 .…”