UPS
A highly surface sensitive technique for the analysis of valence bands and the workfunction of materials
Ultraviolet Photoelectron Spectroscopy (UPS) is similar to application to XPS, the difference being that the ionising radiation, typically below 50 eV, are used. Ultraviolet photons are produced using a gas discharge lamp typically filled with helium (argon and neon can also be used); the photons emitted by helium gas have energies of 21.2eV (He I) and 40.8eV (He II).
As lower energy photons are used, most core level photoemission lines are not accessible using UPS, so spectral acquisition is limited to the valence band region.
Benefits
Applications
- High resolution valence band measurements
- Highly surface sensitive (very sensitive to contamination)
- Work function measurements
- Characterisation of adsorbed monolayers
- Dopant concentration measurements
- Semiconductor junction parameters (e.g. barrier heights and band edges)
Availability
Systems at Harwell and UCL are equipped with UPS capabilities.