Nb and F co-doped anatase TiO2 layers were deposited by low
pressure chemical vapor deposition (LPCVD) at pressure of 3 mtorr using
titanium-tetra-iso-propoxide (TTIP), O2 and NbF5 as precursor,
oxidant and dopant respectively. Resistivity beyond 100 Ωcm for undoped layer was decreased with increasing supply of the dopant
and dependent on the supply ratio of O2 to TTIP and decreased to 0.2 Ωcm by the optimization. X-ray fluorescent spectroscopy showed Nb-content
in the layer was decreased with the O2-supply ratio. X-ray
photo-spectroscopy indicated that F substituted O-site in TiO2 by O2-supply
but carbon-contamination and F missing substitution in the O-site were
significantly increased by excess O2-supply. Further, it was
suggested that the substituted F played an important role to reduce resistivity
without significant contribution of O-vacancies. XRD spectra showed F missing
substitution in the O-site degraded the crystallinity.
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