How to make a very thin plate with some resistance

Question

I'm doing experiments with electric fields and would (ideally) like a very thin solid box (not hollow) as shown in this picture:

It would need a very thin \$h\$ (of about 200 um at most, if possible), an \$l\$ of about 10 cm and a \$w\$ that would allow a resistance of about 180 ohms. Since $$ R = \rho \frac{w}{h*l} $$

that would mean w would depend on the resistivity \$ \rho \$ of the material.

Also, it would really help if the top and bottom surfaces are covered with an even thinner insulator (~5 um would be possible? The smaller the better).

I was thinking about a silicon wafer. Some shops sell it with an \$ h = 130um \$, \$ \rho = 0.01 \Omega m \$ , \$ l = 10 cm\$ which would mean \$ w = 23cm\$. But if \$ \rho \$ is even smaller than better (as long as \$ l > 1cm \$ its good so I can still work on it with my hands)

But I never bought a wafer before and dicing it (a "circular" wafer doesn't suit me at all) seems to be nontrivial, specially for more or less precise (< 30% error) cuts and unfortunately I'm not so handy (I think I will break most of them)...

Also, I saw that we can purchase the wafer with a coating but as far as can tell (which maybe is wrong), its not just for the top and bottom sides, the coating would reach every side of the wafer. Since I want to plug in a power supply to the front and back sides of the wafer, these sides need to be "accessible". Even without coating, I don't know if it possible to solder some wire directly into the silicon to connect it to the power supply...?

Another solution could be graphite or germanium plates?

Is there a better idea than the wafer? If the wafer is a "good" solution, can you recommend some (European would help) manufacturer?

If no thin (small h) solution is possible, then it could be relaxed to \$ h = 1 mm \$ if needed, but having a top/down insulator would be extremely helpful.

Also, please keep in mind that is a hobby experiment, not an application and certainly not for a commercial system so I can spend some money, but not $1000 :).

Answer 1

Thick Film Method. Not a perfect answer, but I can't put a picture in my comments.

The conductive area allows you to connect to the resistive plane. You can solder to the conductive area. Otherwise, there is no easy way to connect to the resistive plane.

I have assumed that you want to connect to the ends. If you want more of a point connection, use a small area of conductive paste.

layers are applied with a screen process, similar to silk screen, except the screen is metal.

The conductive layer is put down first. After each layer, you need to cure at a high temperature. You need a slight overlap between the conductive layer and resistive layer, the registration between layers is never perfect.