I am depositing superconducting thin films (mainly Bi-2212). I have had troubles understanding why their resistance is so high and the superconducting transition temperature comparably low when it comes to films I did way back.
My potential issue:
For the deposition process, the target is rotated by an external motor outside of the chamber leading inside. A while back when my films were good, I had to change this motor. I found the new motor leaked oil into the chamber which might have vaporized and degraded the films during depposition. There was yellow redsidue on the chamber wall.
I cleaned the chamber with ethanol and switched to a motor without oil (or so the technitian ensured me). The chamber was then heated to 800°C under vakuum to get rid of all the residues.
However, I still find a yellowish-brown layer in my chamber after each deposition.
Of course, I also use a cooling trap vor the vacuum pump, so it cannot come from there.
Any ideas on what to do in this situation?
Have any of you had similar issues?
It seen to me you still have some contamination inside the chamber. Not sure if its helpfull for you but i once had a similar problem in a sputtering chamber due to expired vaccum grease, we had to disasemble the chamber and scrub it with a jewelry polishing compound. This type of compound has nanoparticles on it that acts kinda of a sand paper removing the remaining residue on walls, after scrubing it we used isopropyl alcohol to remove the jewelry compound.
I will probably have to do the same then and hope for the best.
Thank you very much for your answer!
It's crucial to address potential sources of contamination in the deposition process for superconducting thin films. The persistent yellowish-brown layer in your chamber could be indicative of residual contaminants affecting film quality and properties.
Here are steps you may consider:
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