I have been working on depositing metal oxide nano-particle dispersions (ZnO, TiO2, NiO) on glass, and baking them to form conductive thin films. I need to know how to characterize the quality of the films produced.
I am most particularly interested in the transport characteristics of the films, but other measurements could help me understand the the effect of changing the processing conditions. What are the best methods, as well as easiest methods, of probing these films, and what information will they reveal?
Furthermore, I encourage any suggestions on how to effectively make conductive thin films from metal oxide nano-particles. Thanks.
Dear James,
The most informative and detailed method that I can think of is conductive force microscopy. This will actually help you map the conductivity and structure simultaneously on a very local level.
I hope this was helpful.
Regards
In our experience, it is also possible for some oxide films to quickly change conductivity from p-type to n-type and then to insulating depending on growth conditions, annealing conditions, and even oxygen exposure afterward. You shouldn't run into that issue with ZnO, but NiO might surprise you, and others. I'd suggest also measuring Hall Effect on the ones for which you aren't certain of the carrier type.
Electrical conductivity is the ability of a substance to transfer (conduct) electric current. It is the reciprocal of electrical resistivity (ohms). Measure resistivity (rho), with four probe method. Then find conductivity, k = 1/rho. For metal material you can use Sigmascope-10.
as Artur Braun (van der Pauw) and Eis. Take a (time) series of Z-spectra (0.1Hz
Bulk conductivity is probably of most interest. There are standard methods for measuring the conductivity. These involve using a gold (or gold coated) probe of a certain radius with a slowly applied (so as not to damage the film) force of an exact amount. I modified a metallurgical hardness tester to do this when I was doing my doctor research many years ago on the conductivity of ruthenium oxide films. You should be able to find the standards in literature.
If you are just interested in sheet resitance/conductivity I recommend the four point probe method as mentioned by Posman Manurung, it is very easy and non-destructive. If you have a way of determining your film thickness and you assume homogeneous anisotropic conductivity you can also derive bulk resisitivity values.
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