Hi folks,

Just a quick question. Can someone explain to me the importance of adding the liquid nitrogen into the chamber?

We curently have a 'cold finger' at the top, this leads into the main chamber where the evaporation takes place. We place our samples at the top of the chamber also, looking down to the evaporation filaments (about 11 inches away, is this too far?)

My main question is this:

Is it possible that putting too much liquid nitrogen into the chamber can affect the surface of the substrate before the evaporation has even taken place?

The reason I ask this is because I am currently evaporating aluminium films at a rate of around 10-12 angstroms/second to obtain a thickness of around 200nm at a apressure of 4x10^-6 mBar. I am having trouble annodisation this surface and i think it is to do with the evaporation.

Any advice is much appreciated?

Thanks

Cat

[Edit Post]

The cold finger is in the system to help remove water vapor - there should be no nitrogen entering the vacuum chamber itself. If you can't anodize the film it may be because the surface is being contaminated - possibly from pump oil in the chamber or the ambient outside the chamber. References: J.K.G. Panitz et al J. Electrochem Soc. 131(10) (1984) 2227 & Anodization of mirrors - How to do it Stan Thomas. <http://astro.umsystem.edu/atm/ARCHIVES/APR95/0129.html> 1999 DMM

[Edit Post]

The cold finger is in the system to help remove water vapor - there should be no nitrogen entering the vacuum chamber itself. If you can't anodize the film it may be because the surface is being contaminated - possibly from pump oil in the chamber or the ambient outside the chamber. References: J.K.G. Panitz et al J. Electrochem Soc. 131(10) (1984) 2227 DMM

[Edit Post]