There is some uncertainty regarding the energy calibration in our UPS measurements. We used gold (Au), a metallic reference, alongside our samples for instrumental calibration. However, since our samples are semiconductors or insulators, direct comparison with metallic Au poses challenges due to differences in Fermi level alignment and surface charging. When plotting the valence band spectra, we observe binding energy shifts across samples. This raises an important question: should these shifts be interpreted as actual changes in the valence band maximum (VBM), potentially caused by doping or defect-induced band structure modifications, or should all spectra be aligned to a common reference—such as the secondary electron cutoff or a selected sample—for consistent comparison? Expert guidance on best practices for energy referencing in UPS, especially when comparing insulating/semiconducting samples to a metallic standard, would be greatly appreciated.