Vacuum Ultraviolet Characterization
Most dielectrics have an energy bandgap that lies between 5-10 eV, which is within the vacuum ultraviolet range (200-10 nm, 5-30 eV). As a result, VUV photons can examine the photoemission, photoconductive, and photoinjection processes within dielectrics. We perform two types of experiments to characterize dielectrics (1) the accumulation of charge within dielectrics during VUV irradiation and (2) the valence-band structure and energy levels of trap states within the bandgap of dielectrics using VUV spectroscopy. In both cases, we monitor the photoemission current and the substrate current.
In addition, VUV can be used to obtain the optical parameters (index of refraction and extinction coefficients—n and k) of various dielectrics in the VUV range.