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.

Raman spectroscopy is an effective tool for stress and compositional metrology in the semiconductor industry. However, its application toward decoupling a complex stress state in semiconductor materials requires the use of liquid immersion lenses that are process line incompatible. In this work, a practical design concept for off-axis Raman spectroscopy is presented. By tilting the incident light away from the normal incident axis, forbidden Raman modes can be accessed allowing determination of the in-plane stress tensor in semiconductor materials. Furthermore, we benchmark off-axis Raman spectroscopy against oil-immersion Raman spectroscopy for stress characterization in 20 nm-wide strained Ge fin field-effect transistor channels. We demonstrate that off-axis Raman allows anisotropic stress metrology without reliance on liquid immersion lenses, highlighting its viability in the process line. The stress state is validated through nanobeam diffraction measurements.

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