Hello,
Au does not form a good metal-oxide interface, we obviously need to insert an adhesion metal layer (Cr, Ti, etc) to make a good bonding with the substrate. I was wondering if there is any way to improve the adhesion between gold and a transition metal oxide film (SrTiO3 thin film) without an extra adhesion layer. Would thermal annealing be helpful? Or plasma cleaning of SrTiO3 surface right before Au deposition? I use electron beam evaporator for Au deposition (~30nm).
I would greatly appreciate any suggestion!
This is all depends what kind of film and what kind of adhesion you want. The easiest approach to improve the adhesion would be to pretreat both surfaces with any atmospheric pressure air plasma (for few tens of seconds would be enough, can use either plasma jet or dielectric barrier discharge - and air treatment should be cheap enough). Even the as produced surface relatively fast gets covered by airborne hydrocarbons, which are typically measured in XPS by a presence of C 1s peak for almost any sample you place from air to vacuum. This might help for sure, yet it is necessary to keep in mind that efficiency of plasma cleaning is not endless, and the shorter the time between treatment and bonding - better it is, in my opinion, few tens of minutes would give the best results, if wait hours - cleaning effect would gradually dissappear due to readsorption. For example you can have a look: Article Influence of humidity on atmospheric pressure air plasma tre...
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Jack Park
look
Fig. 3: SrTiO3 on Au/Ti/LaAlO3 grown at 600°C
in publication
https://www.researchgate.net/publication/3909330_Structural_and_dielectric_characterization_of_SrTiO3_and_BST_thin_films_for_microwave_applications/figures?lo=1&utm_source=google&utm_medium=organic
due to noble nature of gold, it does not make bonds with the material, and some time material is also passive due to upper surface bond formation with oxide and other atoms, not pinning of gold atom is difficult...pretreatment will help but best way too bond it properly is by putting Cr in-between.
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