Silicon, having band gap of E = 1.1 eV, is doped so that the Fermi energy Ef is lowered by 0.23 eV. At a temperature of around 320 K, determine the majority charge carrier density in the relevant band, relative to the electron density in the valence band at 0 K, given (if required) that the density of states in the conduction band is around 1.73 times the density of states in the valence band?