Thin Solid Films, Vol.517, No.23, 6301-6304, 2009
Polarization dependence of the optical response in SnO2 and the effects from heavily F doping
The optical properties of intrinsic SnO2 (TO) and fluorine doped (FTO) are characterized in terms of the dielectric function epsilon(h omega) = epsilon(1) (h omega) + i epsilon(2)(h omega) by electronic structure calculations. The intrinsic TO shows intriguing absorption characteristics in the 3.0-8.0 eV region: (i) the low energy region of the fundamental band gap (3.2 Gamma(+)(1) (valence-band maximum to conduction-band minimum) is symmetry forbidden, and the band-edge absorption is therefore extremely weak. (ii) In the higher energy region (3.9 Gamma(+)(1), transitions (from the second uppermost valence band) is strongly polarized perpendicular to the main c axis. (iii) Transitions with polarization axis parallel to c axis are generated from Gamma(-)(2) -> Gamma(+)(1) transitions (from the third uppermost valence bands), and dominates at high energies (5.1