I deposited Zinc thin films on two types of substrate materials, one is ITO and second quartz substrate. When I calculated optical direct band gap there is difference in energy for 0.2-0.4 eV higher for Quartz.
Is there any reason why I am getting higher band gap for thin films deposited on quartz than on ITO?
Take a look at this article. In my opinion, such phenomena are not uncommon.
Article Influence of the substrate properties on the electronic stru...
Alexander N Titov when deposited on Quartz it increases. So I have thin films deposited in same way and conditions but the one deposited on ITO have lower band gap.
Take a look at this article. In my opinion, such phenomena are not uncommon.
Article Influence of the substrate properties on the electronic stru...
For thin film, the effect of substrate has to be taken into account. I suspect you have better nucleation on quartz (better lattice compatibility and less strain on Zn films from quartz) than ITO. For compressive (negative) strain, the band gap should increase. But without seeing the surface morphology, it is a bit difficult to say. You can check the quality of your film from AFM or SEM and XRD(crystallite size). And check the following papers which should answer your question. Article Effect of substrate-induced strain on the structural, electr...
Manisha Chhikara thank you very much, do you suggest me to do AFM? It is actually very hard to obtain XRD diffraction peak for samples prepared on ITO comparing with quartz. I am not sure how else I can check crystallite size of sample on ITO
Yes, AFM(or SEM), You can compare the surface morphology. You can do PL as well if not done yet. From AFM images, you can find out the grain size of films on both the substrates, you can relate it to the strain as discussed in the paper. If the substrate is more crystalline, the overgrown film has a higher band gap. See this paper that is exactly what I was saying about the crystalline nature of Quartz. Article Substrate Effects on Structural and Optical Properties of Zn...
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