Polarization dependence of the optical response in SnO2 and the effects from heavily F doping
2009 (English)In: Thin Solid Films, ISSN 0040-6090, E-ISSN 1879-2731, Vol. 517, no 23, 6301-6304 p.Article in journal (Refereed) Published
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<h omega<3.9 eV), the optical transitions Gamma(+)(3) -> 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<h omega<5.1 eV) the Gamma(-)(5) -> 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<h omega eV). Heavily F doped TO (FTO) with doping concentrations n(F) = 4 x 10(20) cm(-3) changes the absorption significantly: (iv) Substitutional F-O generates strong inter-conduction band absorption at 0.8, 2.2, and 3.8 eV which affects also the high frequency dielectric constant epsilon(infinity). (v) Interstitial F-i is inactive as a single dopant, but act as a compensating acceptor in highly n-type FTO. This explains the measured non-linear dependence of the resistivity with respect to F concentration.
Place, publisher, year, edition, pages
2009. Vol. 517, no 23, 6301-6304 p.
Tin oxide, Fluorine doping, Optical properties, Polarization effect
Other Engineering and Technologies not elsewhere specified
IdentifiersURN: urn:nbn:se:kth:diva-26007DOI: 10.1016/j.tsf.2009.02.063ISI: 000269930400021ScopusID: 2-s2.0-68349118134OAI: oai:DiVA.org:kth-26007DiVA: diva2:362411
QC 20101109 Uppdaterad från submitted till published 20101109.2010-11-092010-11-092010-11-09Bibliographically approved