Resonant photoemission spectroscopy of materials for photovoltaics
The electronic structure of CuIn1-xGaxSe2 single crystals has been determined by the method of resonant photoemission, and the main regularities of its transformation have been established with a change in the concentration x from 0 to 1. The dependence of the shape of the spectra of valence bands on photon energy has been studied. It is shown that the integrated intensities of photoemission are determined by atomic photoionization cross sections. The processes of direct and two-step generation of photoelectrons accompanying photoemission and the participation of internal states in electron spectra from valence bands were studied. In the case of threshold excitation of the Cu 2p level, two-hole final states in photoemission were obtained. The strong interaction of the holes leads to a multiplet splitting of these states. Using the energy dependence of the atomic photoionization cross sections, the partial densities of the states of the components are determined.