How Does Time Between Depositions Affect Cohesion of Au Layers?

[Si14]

I have deposited about 200nm of Au and I am going to deposit another 200nm layer of Au on top of this layer. All deposition are with e-beam evaporation and are done in vacuum. I have two questions:

1- Do you know how the cohesion between these two layers is?
2- I am going to deposit the second (top) layer of Au, two or three weeks after depositing the first layer. Should I do any cleaning before depositing the second layer? I, personally, think it is not necessary, since Au is an inert material and there shouldn't be any layer formed on top of that, right?

Thank you very much.
Regards.

 

[Mapes]

I have tried this and the second layer doesn't stick well enough to pass the tape test. As soon as you vent the chamber after the first deposition, a layer of hydrocarbons will adsorb upon it and will interfere (to some extent) with the bonding between the two layers. This layer can't be removed except by sputter cleaning in a vacuum.

It's still worth a shot to try, but the line of thinking that a material will remain perfectly clean as long as it's inert is off base.