In my ITO sol contains PVA as a binder/stabilizer. I did annealing and I got brown colored layer instead of transparent layer (After annealing my samples were not opaque but it was not good transparent one). If someone knows what is happening in here please let me know.
If you are doing vacuum annealing, there may be a possibility of creating oxygen vacancy in the ITO film. You can do a XPS study of the film after vacuum annealing to know what exactly happening.
Dear colleague Naveen Harindu,
Have a nice time an good day.
There are two major factors affecting the transmittance, namely, surface
scattering and grain-boundary scattering. If the surface of the sample is relatively rough and its grain-boundary is irregular, the surface scattering and grain boundary
scattering of sample are strong, accordingly inducing a low transmittance in the visible range. The transmittance of the sample increases if surface roughness is decreased or the grain sizes are more uniform and grain-boundary is clear and regular. So the resultant will be the increasing of the transmittance of the sample [Applied Surface Science 256 (2010) 4543–4547].
So the annealing may increase or decrease the transmittance according to the aforementioned factors.
XRD, SEM and TEM can help you to investigate the morphology and the structure of the annealed material.
I wish this is useful and help you.
Yours
A. El-Denglawey
I concur with Shankar that most likely you loose oxygen during the anneal. If you create oxygen vacancy's very often transparant materials become gray/brown. I did have similar experience in the past with ITO and Al2O3. You can check this easily by annealing e.g in x%O2 instead of using vacuum or pure Ar or N2.
Dear Naveen,
Greeting to all colleagues! i would like to add to the answers of the colleagues, that the post annealing temperature of the deposited films are utilized to enhance the the adhesion of the deposited film to the substrate and to enhance the strucural and electric properties of the film.
This is valid for ITO its properties is affected by annealing at different temperatures and different environments. The paper in the given link below has useful information on this topic. The author concluded that the optimum annealing temperature for their ITO films is about 400 degree centigrade. Annealing at 600 results in a worse material.The linkk: http://www.nanomagnetics-inst.com/usrfiles/files/Articles/Ambient-AFM-MFM/AFM5.pdf
wish you success
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