Electronic structure of Cu2ZnSnS4 probed by soft x-ray emission and absorption spectroscopy

The electronic structure of Cu2ZnSnS4 has been investigated by S L-2,L-3 x-ray emission and absorption spectroscopy. An empirical assignment of the most prominent spectral features of the valence and conduction band, respectively, can be made based on a comparison with spectra of corresponding binary compounds and with calculated densities of states. We find that the top of the valence band is dominated by hybridized antibonding Cu 3d-S 3p states, while the bottom of the conduction band is dominated by respective Sn 5s-S 3p states. We also determine the electronic band gap near the Cu2ZnSnS4 surface to be 1.5 (+/- 0.3) eV.