I have titania films growth by ALD and current resistivity is very high (typical 4pp method gives error and multimeter measurements give MOhms values). What experimental methods can be used to reduce resistivity in titania? Thank you in advance
Dear Maksym,
The question which you ask is the general for oxygen-containing materials with ions of variable valency (for such materials presence of the dot defects connected with oxygen vacancies is characteristic).
The simplest method to increase resistivity and absorption coefficient (visible and IR spectral region) in titania films is vacuum annealing (a fore vacuum pump, residual pressure about 10-2 Torr). The demanded resistivity can be received, changing temperature and time of the procedure. Usually vary annealing time at a temperature of 200 - 300 0C. Even more effective way - conducting annealing in a hydrogen atmosphere. This is stated in the article "The role of hydrogen in the reduction of lithium niobate crystals during their thermal treatment in vacuum", Elektronnaya Tekhnika. Ser. 6. Materiali, issue 8 (207), p.3 (1985). In the near future this article I will present on my page.
Regards, Leonid A. Skvortsov.
Dear Dr. Skvortsov
Thank you for detailed description. I would really appreciate if you could find the paper.
Best regards,
Maksym P.
I do quite a lot of photoemission using titania crystals and we usually anneal at 500-600 degrees centigrade at pressures less than 1e-9 mbar (as part of the sputter/annealing cycles we used to clean the surface) and see that the resistivity drops sufficiently such that charging of the surface is not problematic.
Sorry - I have never measured the resistivity at different annealing temperatures/times but figured I should post on the off chance it could be a good starting point.
to find the resistivity do not use multimeter...
if your sample is in powder form (then make a pallet) or if it is in the thin film then use four point probe method to find the conductivity.
best regards
Nouman
Thank you, Robert and Nouman. Those are precious advices.
Best regards
Maksym
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