How to get deep thermal oxidation of Al thin film (~40 nm) deposited on glass substrate?!
Instead of oxidizing an deposited aluminum film you can deposit Al2O3 by exposing the substrate to Trimethylaluminum and water at 10-6mbar on the heated glass substrate at elevated temperatures.
Depending on the vacuum you make the deposition in, you could already have partial oxidation throughout the film thickness. Heating the glass plate in air will complete the oxidation and accomplish what you want.
Why you don't anneal your film in air or oxygen at certain temperature?
Thanks for all.
@Christian Pettenkofer .. I need to keep an Al layer under Al2O3 to serve as a Gate structure in the organic transistor while the oxide layer represents the gate dielectric. Therefore, the density of oxide surface defects should be very low . Is this method proper for this purpose.
I have tried to use annealing process in air at 200 C for several hours but the oxide layer which formed was ultra thin about 2 nm. What I need is a partial oxidation with thickness at least 10 nm.
@Hatem Maraqah It is interesting , I wll read it.
Thaks again.
You could also try to anodize the Al thin film. Although the anodic alumina formed in this way is usually of porous-type and can have some impurities, you can easily tune it by changing the electrolyte type, concentration, temperature and applied potential used during the anodization process (http://faraday.fc.up.pt/cfp/Members/jmenezes/walls/nanopore-formation-mariana.pdf). Additionally, there is always an alumina barrier layer formed on top of the Al thin film, with a tunable thickness that could go from around 25 to 200 nm.
Aluminium surface oxidation tends to be self-limiting. Beyond a few nanometres you don't get much more oxidation, that's why aluminium is so resistant to corrosion. Growing an oxide layer is probably a much better and more controllable option.
Sure, the best way is to grow through magnetron sputtering, Al target in presence of reactive Oxygen gas at your controlled conditions on glass substrates
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