I'm planning to deposit a thin layer (40-50 nm) of metal oxides on ITO coated glass slides. Can I use electron beam evaporation for this? I'm worried about the oxygen vacancies associated with such films.
Is it possible to overcome the oxygen vacancy by creating a oxygen rich chamber while deposition?
The intense heat generated during the deposition procedure would destroy the ITO coating. You can try this on metal coated quartz substrate.
An easy and controllable way to deposit ZnO is by MOMBE or ALD using diethylzink (DEZ) and water as precursors. Just expose the sample heated to 250°C-300°C to DEZ and water at 6.10-6mbar and you obtain clean carbon free ZnO. If you want to dope just add a little trimethylAl.
Check the following articles
http://www.sciencedirect.com/science/article/pii/S0169433298006540
http://www.sciencedirect.com/science/article/pii/S0040609004009149
http://iopscience.iop.org/0268-1242/18/6/322
http://dx.doi.org/+10.1063/1.2204333
The melting temperature of theses material is high, sputter might be better way to deposit.
Electron-beam evaporation is commonly conducted using a high-vacuum chamber (due to the interaction of the electrons with any gas). Even under reduced vacuum conditions (increased pressure, as far as it is possible), my experience is that you end up with a slightly under-stoichiometric metal oxide exhibiting vacancies (especially if you have to cool the substrate during deposition). Only post-treatment in oxidizing atmosphere (at higher temperature) would solve that problem.
But alternative techniques like PLD do so as well as they are performed under high-vacuum conditions. Depending on the metal oxide sputtering (not as homogeneous as e-beam evaporation or PLD) or a precursor-based technique (that doesn't necessitate any thermal oxidation) like ALD, as already mentioned above, would be suitable (although ALD takes a while to deposit such "thick" layers).
Short answer: No. If you evaporate a compound material then, due to the different boiling points, the one component always evaporates faster so you will not get stoichiometric transfer to your substrate. Read the Handbook of thin film deposition. Articles by Draper (I think) mention this. Sputter deposition may be your cheapest way to go but results are not always predictable. PLD is also an option until you need a large wafer size sample. Good luck.
You can do the coating keeping the chamber pressure at 1-2 x 10^-4 mbar of O2.
Try to keep the substrate at maximum possible distance ( ~ 20cm if it is a12" bell jar) from the e gun.
Dear Ramesh Vasan,
You should use pressed palets made from powder of metal oxide to be deposited.
It is possible to deposit vacancy free TiO2 thin films (high transperancy and very, very low conductivity at room temperature) by the electron-beam evaporation of pressed TiO2 powder (vacuum 5*10^-5 mbar). I did it many times.
I tryed to deposit ZnO thin films the same way. However, ZnO is different comparing with TiO2. TiO2 target can be melted by electron beam, but you can not do the same with ZnO target. It sublimates in vacuum at high temperatures. It is possible to deposit ZnO thin film but the deposition process is not controllable.
You should try with other metal oxides. I think that some of them can be deposited under contollable conditions by means of the electron-beam evaporation.
Good luck!
Its possible of course, but the deposition process is not controllable.
We are growing MgO tunnel barriers in spintronic devices by means of electron beam evaporation. An epitaxial growth of the MgO tunnel barriers can be achieved e.g. on a GaAs(001)-(4x6) surface. More details can be found in the following publications:
http://dx.doi.org/10.1063/1.3646390
http://link.aip.org/link/doi/10.1063/1.4769180
http://dx.doi.org/10.1143/APEX.5.033003
http://dx.doi.org/10.1063/1.3476265
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