Hi,
I need to deposit SiO2 on top of sputtered gold films and I find that tha adhesion between both layers is too bad. I ca not use any other material as it will interfere in the performance os the device.
I am thinking in testing a O2 plasma between the Au and the SiO2 depositions, a BIAS, a time of codeposition...
Anyone has experience in this multilayers? If so, I will really appreciate a suggestion or hint.
Thank you very much,
Ana
Hello.
You can try to use oxides with high refractive index such as TiO2, ZrO2. This oxides will be adhesive layer between gold and SiO2. Thiсkness of such adhesive layer should be 10 nm or less. In this case adhesive layer would not influence on optical properties of coating.
Good luck!
Alexander.
Hi,
The poor adhesion is due to the electronegativity of gold and the oxide which are similar and therefore repulse each other somewhat. Using an adhesion layer such as titanium or chromium , mitigates this. See: https://www.researchgate.net/post/Why_are_Cr_and_Ti_good_adhesion_layer_in_thermal_evaporation
https://www.researchgate.net/post/Why_chromium_thin_films_are_used_as_an_adhesion_layer_in_several_applications
Ti ultra thin film (~10 nm) will not only form Au-Ti alloy but also it will strongly bond with SiO2. In addition, I recommended to avoid room temperature deposition in order to obtain high quality films.
You can flash an ultrathin layer of Chromium by thermal evaporation so that it remains transparent, (you may need probably the reflectivity of gold for your study), and then deposit your SiO2 layer on the Cr layer.
,
Ana,
if you will want try to use the ultra thin layer of Ti or Cr you should understand that 10nm Cr give only ~15% of transparence, 5nm Cr - ~35% T, 3nm - ~55-60%T
So, if optical properties of gold coating is important you need to use Cr layer less 1nm. But in this case Cr/Ti may not working like adhesive for gold/SiO2.
- Badges
- Science topic
- Similar topics
- Physical Sciences
- Materials Science
- Materials Chemistry
- Polymer Chemistry