Partial density of states in the CuInSe₂ valence bands

The valence band spectra of a vacuum cleaved CuInSe₂ (011) surface were measured with synchrotron radiation at photon energies between 16 and 95 eV. The strong dependence of the photoionization cross section of atomic levels between 28 and 60 eV is used to divide the valence band emissions into contributions from Se 4p and Cu 3d states in order to map the respective partial density of states. The derived partial density of Cu 3d states to the total valence band density of states is around 50% in the upper part of the valence band and about 75% at its maximum corresponding to non-bonding Cu d states.