You need the resistance of whole sandwich? As far as I know the current will pass through the most conductive layer, so you will get the resistance of Ti layer only.

Hi Çoruhlu;

You may be should increase the oxygen flow into the chamber during the proses. Because as you know, the resistance of ITO films decreases due to the number of vacancies. It also depends on your sputtering temperature. But especially the oxygen vacancies causes free electrons in the structure. Namely one oxygen creates two additional electrons. So the carrier density increasing and the resistance is decreasing meaningly. However, the resistance of ITO films increased with the decrease in oxygen flow. This increase may be due to the fact that severe oxygen deficiencies may deteriorate the structure.

Regards.

Thank you very much for your answers.

@Arsen: Yes, I need whole sandwich structure and then I would compare it ITO single layer with the same thickness. You are right that the intermediate metal layer  is dominant factor in the sheet resistance. In some studies the contribution from ITO layer is neglected, too.

@Çetinkaya: Mostly we use only Ar as working gas. We had also used oxygen in some experiment and result was reasonable (but we have used silver as a metal). At least I had measured the sheet resistance. This is consistent with your explanation. Would you give me some references about the oxygen vacancies and sheet resistance (for ITO)? I want to learn the physics behind it and then I will use it to interprete my results in my thesis. 

Ti at low deposition rates may be oxidized to TiO2. ITO could also be a problem. Check its sheet resistance too.

Hi Torgay,

I just think you're facing a measurement problem, not something to do with the ITO process. Probing a oxide layer is difficult, normally you need something to have the proble needles go into (soft Au,Ag, Cu, Al) to be able to make good contact. Furthermore ITO behaves as a kind of semiconductor due to the vacancies present in the material. If you have a metallic probe needle you might just have a very high difference between work function of the metal and Fermi level of the ITO and you are maybe creating a Schottky contact. Most efficient is to deposit a thick aluminium layer on top of the ITO. This will have good adhesion and should give no Schottky contact. If you put a Van der Pauw pattern on the sample you can do an accurate four point probe measurement. Of course you have to compensate for the Al, but if you make this thick it will have hardly any influence on the total sample resistance. Also be aware that you measure this construction in the dark. ITO because of it's complicated band structure might be influenced by UV light, this changes the resistance.

Hi Çoruhlu;

You can read attached file. May be its references also could help you.

Regards.