Measuring the thickness of a thin film of bismuth for Hall Effect experiment.

[adwodon]

Hello there,
I'm an undergrad in my 3rd year and I'm doing an investigation into the 'Preparation of Thin Films and their use in Hall Effect measurements.'

We are making thin films of bismuth on glass (with pre drilled terminals) in a vacuum system.

The way they suggest measuring the thickness is by measuring the mass of the film, although they are quick to point out that the scales arent the most accurate and will only give a very rough approximation.

One way I know read would work would be to have a rectangular / square segment of bismuth and measure its resistance, although I am not entirely sure how to go about this from a practical perspective as the shape of the bismuth film isn't rectangular, is it possible to do this for any shape provided you can easily calculate the area?

What other methods would there be to calculate the thickness. We were told we could request any equipment within reason, I doubt they would give us high tech expensive spectroscopy equipment for example, however if you know of any reasonably accurate and not overly technical, as I am only an average 3rd year undergrad, then I can at least ask and find out if its possible.

 

[K^2]

Numerically, you can compute resistance for any shape, but you basically need to do finite element analysis. If you're comfortable with programming, it's not that hard to do.

If you place an coil next to thin conductor film and apply AC, the inductance of the coil at different frequencies will depend on the thickness of the material, so long as the film is thinner than the skin layer at that frequency. This could give you precision of about 1% in measuring the thickness if you set it up right, and all you'd need is an oscilloscope and a function generator.