Excitonic and band-band transitions of Cu2ZnSiS4 determined from reflectivity spectra

• Reflection spectra of Cu2ZnSiS4 were studied for E⊥c and E∥c light polarizations.
• Three excitonic series are revealed in the reflection spectra at 10 K.
• Model of exciton dispersion and the presence of a dead-layer.
• Exciton Rydberg energies and free carriers effective masses were calculated.
• Reflectivity for E⊥c and E∥c was analyzed in the region at 3–6 eV at 300 K.

Exciton spectra of Cu2ZnSiS4 single crystals are investigated by reflection spectroscopy at 10 and 300 K for light polarized perpendicular (E⊥c) and parallel (E∥c) to the optical axis. The parameters of the excitons and dielectric constant are determined. The free carriers effective masses have been estimated. The room temperature reflectivity spectra at photon energies higher than the fundamental band gap in the polarization Е⊥с and E∥с were measured and related to the electronic band structure of Cu2ZnSiS4.