I would like to ask you for a help.
I am producing metallic coating on my lab glass (Ag/ZnOx/SnOx/TiO2). Everything looks fine after the pvd process. The problem starts when I try to heat up the glass above Tg. From the tin part of glass I have brown-orange spots/marks.
If I try to investigate by Raman, I see very probably amorphous material. SEM shows me the same chemical composition like the coating itself = heavy Zn, Sn (roughly 75% Zn+Sn), Ag, Ti (roughly 10% Ag+Ti) + Fe, Al, Na, Ca (probably caused by diffusion from glass). In the glass volume I see just Ag(0) - nucleated silver causing this brown-orange colloration. The problem is that I do not see anything before heating treatment above Tg. Why?
When I check the defect on the microscope I see something that looks like a peel. I am able to remove the top peel (heavy Brown) and I am getting just Ag nucleated crystals in the glass. So the peel has the composition mentioned above (Zn,Sn,Ag,Ti,Fe,Al,.) and the peel is removable.
Please could you give me any help how is it possible that I have these brown defects on the tin side of my glass? Should I consider some problem with the PVD chamber?
Thank you very much,