Dresden 2006 – scientific programme
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DS: Dünne Schichten
DS 24: Poster presentation
DS 24.15: Poster
Tuesday, March 28, 2006, 15:00–17:30, P2
Reactively sputtered TiO2 layers on SnO2:F substrates: a Raman and SPS study — •Julius Mwabora1, Klaus Ellmer2, Abdelhak Belaidi2, Jörg Rappich2, and Thomas Dittrich2 — 1Department of Physics, University of Nairobi, P.O. Box 30197-00100 Nairobi, Kenya — 2Hahn-Meitner-Institut, Glienicker Str. 100, 14109 Berlin, Germany
Reactively sputtered TiO2 layers on SnO2:F substrates were investigated by Raman and surface photovoltage spectroscopy (SPS). The deposition temperature, the O2 / (O2 + Ar) ratio and the deposition time were changed systematically. With increasing temperature, the layers become crystalline while rutile is dominating. Anatase starts to form at prolonged deposition and at lower O2 / (O2 + Ar) ratios. The workfunction and its light induced change show only well defined trends for the temperature dependent deposition (increase with increasing deposition temperature). Since the SPS saturates under absorption, the SPS signal is related to the density of states in the spectral region near the band gap of the TiO2. The values of the band gap and of the energy parameter of the exponential tails decrease from about 3.28 and 140 meV to 3.14 and 60...80 meV with increasing deposition temperature of about 30 ∘C to 380 ∘C. The TiO2 layers deposited at 380 ∘C are of high electronic quality as demonstrated with SnO2:F / TiO2 / graphite Schottky-diodes.