Elliott's model and thermoreflectivity: Application to the layered structure ZrSe3.

Abstract

The Elliott model has found widespread use in the analysis of semiconductor absorption data. In this work, its application has been extended to reflectivity and, in particular, to thermoreflectivity data. The layered semiconducting compound ${\mathrm{ZrSe}}_{3}$ is a suitable material for such a study, since its structure produces a negligible surface effect, thus facilitating the analysis. Good-quality single crystals were grown and the thermoreflectivity was measured between 40 K and room temperature. Taking into account both the band and exciton contributions, an excellent fit was obtained allowing a characterization of the excitons in ${\mathrm{ZrSe}}_{3}$. A large exciton binding energy was found (49 meV) along with a large value of the coupling constant, illustrating the importance of the electron-phonon interaction in this material.