Ultraviolet binding energy

Figure 4.31 shows ultraviolet photoelectron spectra recorded during the same interface experiment shown in Fig. 4.26. A clear transition from the Cu(In,Ga)Se2 valence band structure with a valence band maximum at 0.8eV binding energy to the ZnO valence band structure with a valence band maximum at 3eV is observed with increasing ZnO deposition. The well-resolved valence band features are enabled by the in situ sample preparation. Also very sharp secondary electron cutoffs are obtained, which allow for an accurate determination of work functions. The work functions of Cu(In,Ga)Se2 and ZnO are determined as 5.4 and 4.25 eV, respectively. These result in ionization potentials of 6.15 and 7.15 eV for Cu(In,Ga)Se2 and ZnO.

An ultraviolet photoelectron spectrum is a plot of electron binding energies versus intensity, it provides detailed information on the electronic structures of a solid in the valence region... 

Free Atom Subshell Binding Energies, in Handbook of X-ray and Ultraviolet Photoelectron Spectroscopy (Ed. D. Briggs), Heyden, London, Philadelphia, Rheine, 1977. 

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