Were the SEM micrographs (SEMM) generated under identical conditions? Above SEMM looks like film structure even though the surface is unclear due to poor contrast and low resolution. The second SEMM seems to be formed ZnO particles. ZnO formation proceeds through the 3 step process, such as particles nucleation, growth and Ostwald ripening. The presence of Cu in the system may hindered the growth process of ZnO particles and favoured the Ostwald ripening after nucleation, resulted particles with uneven/irregular surface. The picture of ZnO-Cu particles should be taken under higher magnification with lower EHT and WD.

Hello, Fateme,

How did you prepare the thin films? Sputtering? What about the substrates? The film morphology not only relies on the material composites and also the the deposition procedure. You may try different deposition conditions to see what's going on.

Very best

Xuhua

I have no idea but it is an interesting example of how worderful is Nature. Please can you added the scale of both microphotographs?

Md. Abdur Rahman

Thanks for your answer

Yes, both SEM micrographs were generated under exactly identical conditions.

I have another SEMMs, that all of them show this morphological difference.The first SEMM is related to pure ZnO and the second SEMM is related to doped(Cu) ZnO.

Xuhua Wang

Hello, Xuhua,

I prepared the thin films with Sol-Gel method(dip coating) and used the glass as substrate.

P. Grima Gallardo

Yes, it was really interesting for us, but we could not find a significant reason for that. I used other elements as dopants(as Ni), but their thin films morphology was almost like pure zinc oxide, while copper completely changed morphology. You can see SEMMs with scale bar in attachments.

It seems that for pure ZnO you have "laminar" structures that are formed over your film and for Cu-dopped ZnO these structures do not form. I suggest SEM (I hope that this technique is avalaible for you) measurements on these structures in order to be sure of their stoichiometry and also in the Cu-dopped ZnO.

All ideas give by dear researchers above are good approaches but according to my experience doping should not effect on the structure properties such as materials formation in regard of crystal growth and structure. It affects strongly on physical properties such as optical and electricaI. However doping means extra amoun of foreign elements in around part per million. For more percentages crystal structure and growth conditions will be affected and if reaches to one percentage and more then alloy system or disocoation as a second phase will be expected.

All the explanation given by the numerous dear researchers are worth important which also enhance my knowledge. But, according to my observations, the structure of the ZnO would have been changed at specific percentage of the Cu, like (30% or any other).

Dear Question asker,

please prepare the different samples with various concentrations of Cu doped in ZnO and evaluate the minimum %age of Cu doped in ZnO at which morphology of un-doped ZnO can withstand . After that you will be able to explain the clear difference between doped and un-doped ZnO.

For your knowledge, you can go through articles given below which explain the Cu doped in IrO2 structure.

1. https://pubs.acs.org/doi/10.1021/acsenergylett.7b01032

2.http://pubs.rsc.org/en/content/articlelanding/2015/sc/c5sc01251a#!divAbstract

Regards

Tariq

Omar M S

Thanks for your answer

According to the results of xrd, each films have a polycrystalline hexagonal wurtzite structure (JCPDS card no. 36-1451) while the diffraction peaks of copper oxides (CuO or Cu2O) were not detected.

Muhammad Tariq Thank you very much for your answer . Do you know why the structure of the ZnO would have been changed at specific percentage of the Cu?

Dear Moosavi

The compound you try to prepare is not a copper doping case as I mentioned in my previous statement the Cu percentage you added makes an alloy case for the material. Then if you don’t have any second phas, that’s what you said in your comment, you a complete solid solution between ZnO and CuO. Of course the case should mean exchange some Zn lattices by Cu and new structures could be obtaimed.

Dear Omar M S

I want to ask you to read my article and tell me your opinion about the results in it.

Article Effects of Cu doping on nano structure, morphology and photo...