A Cu/ZnO bilayer film is deposited with RF sputtering at room temperature
The XPS-depth was conducted and we found that the Cu diffuse into ZnO2 layer.
The Cu2p3/2 peak located at 932.6 eV (from Cu layer) then shifted about ~0.3 eV to higher binding energy.
No CuO (934 eV) nor Cu2O (932.5) peak/shoulder is observed, as depicted in the attachment.
Can anyone please comment on that phenomenon?
Any advice and suggestion are welcome. Thank you.
Hi,
Did you use Argon sputtering for depth profiling? In that case, sputter induced reduction of Cu as well as Zn is possible (check Zn XPS too). Sputtering conditions matter a lot it should be reduced to avoid any artefacts.
I don't clearly see the Sat. peaks which is typically observed above 940 eV (and one above 960 eV) for CuO and a weak Sat. Peak above 940 eV for Cu2O. There are several reports on metal-oxides sputtering induced reduction in XPS. This could possibly sputter effects. Check literature. Hope this clue might help you.
Dear colleague Firman Mangasa
Have a nice time and good day.
Please use XRD and TEM to check the structure of mentioned material it may be changed!
Yours
A. El-Denglawey
@Dear Dr. Santhanagopalan, Thank you very much for your suggestion. Yes we use Ar for sputtering. In fact the for early cycles, we set higher sputter rate for the upper layer (Cu layer) then we decrease the rate when closser to ZnO2/ZnO layer. After doing some literature study, we guess this is due to the sputter induced reduction as you mentioned. Therefore, we intend to redo the XPS experiment to confirm this phenomena.
@Dear Dr. Eldenglawey, Thank you very much for your advice. Based on GIXRD, we are unable to find any significant structural changes at the interface of Cu/ZnO2 layer.
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