Dear Researchers,
I have to do the Dielectric measurements of the BiFeO3 thin films. In order to study the Dielectric properties, I am not sure How to perform dielectric measurements. Kindly, disclose to me the procedure in detail.
Thank you in advance.
Have a good insulating substrate.
Put an adherent metallic electrode on top of the substrate. This electrode layer will be your bottom contact.
Then grow your insulating film on top of the electrode layer.
Finally deposit top of your insulating layer (say BFO) dot electrodes of small diameter of 1mm to 2mm. In this way you will make a MIM strcuture and knowing the area of the top electrode, and the thickness of your dielectric film you can measure the capacitance with a LCR meter, and then calculate the dielectric constant of the film.
Use any standard LCR meter/ impedance analyzer with a parallel plate arrangement.
Place your sample between those parallel plate electrodes to measure its dielectric property
Dear Shubham Roy
Thank you for your response.
I am talking about thin films.
Dear K. Sreenivas Sir,
Is it not possible to do the measurements if we deposit the thin films on a conducting substrate.
Dear Nadeem,
How did you deposited BFO. What is your BFO thickness. What is the substrate have you used. As suggested by Sreenivas, you can make DOT electrode on either side of the film.
Please check some of my thin films papers. Maybe you will get some idea for your question.
Wish you good luck.
Dear Venkata Ramana Mudinepalli Sir,
Thank you very much.
I have deposited BFO thin films on Si substrate using PLD. The thickness of the thin films ranges from 100-150 nm.
Is it possible to do the PE and dielectric measurements of these films or I have to deposit films again for these measurements.
Since bottom electrode is not there presently to make the geometry like capacitor.
Dear Nadeem,
Whether it is 100 or less, we can do all electrical and ferroelectric properties of BFO thin films. But you should make proper electrode before for this measurements. You can try once to measure, if not possible try to do another film. Don't worry it is not a big issue. You will be succeed to get good properties on BFO thin films. Have you done XRD on BFO? If yes, please send me some details on my personal email, [email protected].
Hi Nadeem, since I am also working on similar project I am sharing my experience. The standard process is the same as Dr Sreenivas described. I grown BFO on conducting SrRuO3 substrate and deposited Pt top electrode on it for electrical measurements. But the problem is there is short-circuiting when I try to connect top-top or top-bottom electrodes. In my opinion, the shorting is coming from diffusion of Pt metal vapor through pin-holes on the surface, therefore, the deposition method is very important. You may succeed if you could deposit very smooth film of BFO that intrinsically tends to grow little rough with RMS roughness around 5 nm. Best of luck! And share whether you got success in the measurement or not.
Dear Venkata Ramana Mudinepalli Sir,
Thank you very much.
I have done XRD measurement of the BFO thin film and I have sent you the data.
Dear Mahendra Acharya
Thank you very much for sharing your experience with us.
Have you made both the contacts on the top of the film for the dielectric measurement.
Definitely I will share my experience with you.
Just to add to the above replies, there are also contact less methods available, though they are expensive, but they can be essential if there is problems forming a capacitor structure without short circuits and pinholes. See for example:
https://speag.swiss/products/dak/dak-dielectric-probe-systems/dak3-5tl-p-200mhz-20ghz/
Dear Phil Denby,
Thank you very much for sharing information about this technique.
I think this facility will not be available in India.
Hi Mohd. Nadeem , we have tried both top-top and top-bottom approach. The top-bottom approach seemed to be more effective for our case.
Dear Mohd. Please find this paper
Lead-free piezoelectrics: V3+ to V5+ ion conversion promoting the performances of V-doped Zinc Oxide
https://www.nature.com/articles/srep41957
I have also attached the schematic from that paper...
I hope its helpful to you...
Recommend the answer if it helped you.. so that it can help others
Hi Mohd. Nadeem!
In my case, I fabricated BFO on ITO substrate. To deposit the electrode on the top of the BFO film, I used the electron beam lithography system to deposit Al pattern with deposit rate 0.3A/s, thickness 300nm. You need to make sure that your sample has good adhesion and high density.
Good luck!
@Nura Nguyen Hi, how do you control the adhesion and density of the material? BFO deposits in 3d growth mode with basket-weaved like pattern, how do you make sure that there is no short-circuit between top and bottom electrodes.
Hi Mahendra Acharya , I don't know which method you use to synthesize. For me, I control the adhesion and density by changing the temperature as well as pressure through hydrothermal method. I also make seed layers to make sure that there is no short-circuit between electrodes.
Nura Nguyen Thank you for the comment. I used chemical vapor deposition technique for growing BFO. Can you please elaborate little bit about the seed layer and how do you make it? Thank you very much.
Mahendra Acharya A seed layer was deposited on the substrate via sol-gel spin coating method as a template to grow BFO with various morphology. Prepare sol-gel solution with precursors and solvent, after dripping the sol-gel solution onto the substrate, under the speed and time set for the spin coating machine, a thin film is dispersed on the substrate’s surface. To adjust the seed layer thickness, repeat several times the spin coating process to increase the layered deposit on the substrate.
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