Band-Gap Assignment in SnO2by Two-Photon Spectroscopy

Abstract

We present for the first time two-photon measurements on rutile Sn${\mathrm{O}}_2$. The detailed polarization analysis yields ${{\Gamma }_3}^{+}$ symmetry for the direct forbidden $1S$ exciton and the upper valence band. Our results clear up the long-standing controversy concerning the symmetry of the upper valence band.