Generally 4 point probe method used to measure the resistivity of a thin film. Can anybody give queries: "is it possible to measure the accurate resistivity of a thin film with substrate". Thank You.
Generally, substrate are highly insulating materials and their conductivity is negligible as compared to material of the films. In four probe method current flows through the material of the film rather then substrate. Hence , the voltage developed in other two probes is due to the film and not the substrate. This way we measure the resistivity of the thin film and not the substrate.
I don't think so. Resistivity measurement including substrate requires different transport mechanisms separately for substrate and substance. In my opinion: Even electrical field will differ inside the layers (substrate and substance) individually.
Generally, substrate are highly insulating materials and their conductivity is negligible as compared to material of the films. In four probe method current flows through the material of the film rather then substrate. Hence , the voltage developed in other two probes is due to the film and not the substrate. This way we measure the resistivity of the thin film and not the substrate.
Suppose I used an insulating substrate. Layerwise deposition have done. How i consider the resistivity of whole thin film (in case of multi-layer).
you can use an insulating substrate or you can do the following point
1- measurment the resistivity of substreat only
2-measurement the resustivity of thin film on substreat
3-measurment the resustivity of thin film on insulater substreat. then compared the three points you get the results
As per experimental evidence: it is not possible to measure the accurate resistivity of a thin film with substrate. Because owing to the uncertainty in the sample geometry, the absolute values of the resistivity ,however, may be in error by a few percent. It is generall that, sometime the noise components of the temperature and resistivity signals were resolved by subtracting best-fitting straight lines and cubic splines.
Hi all, I am currently doing similar experiment. I am trying to measure the sheet resistance of a silver film of 20nm thickness with a 4-point probe(force I=1mA, compliance=100v). I tried to use 2 substrate, glass and silicon wafer and get significantly different reading on both case. The glass substrate shows a reading of >450k Ohm/cmsquare while the wafer reading shows inconsistent readings across the areas of 10 to 50 Ohm/cmsquare.
I was wondering if the substrate actually affects the sheet resistance reading? and if there is any way for me to improve the reading consistency in the wafer substrate? Thanks!
Edwin, the 4 point probe technique measures the effective resistivity of the film plus the substrate. If the substrate is insulating (like glass), you get just the properties of the film. If the substrate is conducting (like silicon), you will measure a convolution of the properties of the film and the substrate.
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