Hello
When it comes to thin-film which one is more desirable? (Particularly, where the thin film is used as the first layer of a multi-layer thin films fabrication)
1- a film with a higher internal tress and higher Tensile
Strength?
or
2-a film with a lower internal tress and lower Tensile
Strength?
Thank you for your time and help.
Best Regards
Ali
As far as I know, desirable is practically always compression since the surface - coated layer or generated zone of the same material - is produced to protect the surface, i.e. it should not form cracks which causes corrosion or other failures. If possible it should repair itself, cf. our teeth. This means that the layer below is under tension since everything has to be in equilibrium. For a multi-layer system this might have a complex stress-strain construct especially since some layers are less strength than other. Too high stress can also damage the entire system (spalling observed in coated materials but also in quenched and tempered surfaces like railroad tracks) so that the investigation of stress is essential in practically all technical fields.
Dear colleague,
Materials properties are normally tuned, targeting a specific application. Lower or higher stress/tensile strength, everything has a particular application.
These properties can be modulated following "Structure zone diagram". For more detail about this, kindly check this literature
A structure zone diagram including plasma-based deposition and ion etching
http://www.sciencedirect.com/science/article/pii/S0040609009018288
this will certainly clear your doubt.
When you say internal stress, is there much difference between external and internal stresses in a thin film? Internal as in in-plane or through thickness?
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