XRD measurements of TiO2 thin films coated by sputtering method gives only amorphous peaks corresponding to SiO2 (glass). How to make XRD measurements of the thin films (TiO2) without the background glass (SiO2)peaks?
You are going to want to have a much lower incident angle. You will want to do scans with incidence angles between 0.05 and 0.5 degrees. If you have an idea of the density of your thin films, you can determine the penetration depth of the X-rays into your films using the Beer-Lambert law.
I(f)=I(i)exp(-μρx): where I(f) and I(i) are final and initial beam intensities respectively, μ = mass absorption coefficient, ρ = density, and x is the distance. Tables for some of these values are available on the NIST website linked below.
http://www.nist.gov/pml/data/xraycoef/
try glancing angle XRD it is useful for analysis of coatings and thin films
For very thin films (~ 5 nm or thin) glancing -angle XRD may work (take the incident angle very low (~ 1-5 degree).
Further, you may deposite the same film by proving the little high (~ 200 C) substrate temperature. then you can try powder XRD or G-XRD.
Dear Aditya Sharma Sir,
I have coated in 1micron thickness of TiO2 compound using sputtering. But the Powder XRD patterns of the thin films shows only the Glass substrate's broad amorphous peaks. Now what can i do sir?
You are going to want to have a much lower incident angle. You will want to do scans with incidence angles between 0.05 and 0.5 degrees. If you have an idea of the density of your thin films, you can determine the penetration depth of the X-rays into your films using the Beer-Lambert law.
I(f)=I(i)exp(-μρx): where I(f) and I(i) are final and initial beam intensities respectively, μ = mass absorption coefficient, ρ = density, and x is the distance. Tables for some of these values are available on the NIST website linked below.
http://www.nist.gov/pml/data/xraycoef/
Glancing angle will be better to get the result. If you are interested, you can send the samples to me.
It depends on the thickness of the films. Glancing angle incidence with X-rays will do the job for structural characterization
Use the same alignment and scanning conditions and compare the XRD spectra of an identical glass substrate with nothing on it. Then overlay the two curves. If they are identical then you have no crystallinity in the TiO2 - at least not within your experimental resolution (assuming that the XRD measurement and sample alignment were done correctly and optimally).
You can try to confirm this by other measurements such as electron diffraction in a TEM, EBSD in an SEM etc.
RHEED (Reflection High Energy Electron Diffraction) can be a suitable analysis, alternative to GAXRD/GIXRD.
As mentioned by others, Glancing Incidence angle X-ray Diffraction (GI-XRD) is a good method for thin film characterization. Varying the incidence angle, you can also control the penetration depth.
It does depend on the capability of the XRD unit that you have available, the option of Glancing Angle XRD (or Grazing Incidence XRD) is really a fundamental solution for you. Provided you can drop the angle of incidence to
If you used sputtering, it is quite possible that the film is amorphous as well, which will make it hard to distinguish between your film versus substrate peaks. First you should run the substrate alone in XRD and in glancing angle XRD, then run the substrate with TiO2 film on it in both as well, and if you cannot distinguish between film and substrate after that, then try another substrate. Hope that helps.
As said by others glancing angle is best option to test the thin film with removal of substrate effect. In your case since thickness is in micron the incident or fixed angle can be 1.5 to 2 degrees . But as u said u prepare your sample using RF technique, it is difficult to get crystalline phase. By controlling oxygen pressure during sputtering with Ti target one can easily get crystalline phase or one has to do annealing during or after sputtering to get crystalline phase. Check ur case. Also confirm crystalline phase using Raman spectroscopy.
Dear by Changing the incident angle you can study the thin film characterization by XRD use.Also by proper adjusting the angle you can manage the penetration depth of the beam.
SiO2 in glass is amorphous, so it is expected that you will get a large hump preferably in the low 2-theta region (10 to 30 deg) instead of having any PEAK from SiO2, if you do simple XRD. GI-XRD will reduce the problem a lot. However, as mentioned by Corson Cramer, the sputtered TiO2 may have some amorphous nature as well. So, a post deposition annealing in air or oxygen may be found fruitful (or heating the substrate in oxygen environment during deposition). If you do not have the option of GI-XRD and do not want your sample to be annealed/heated, simply deposit it on some gold foil or silicon wafer. This will give you some distinguishable XRD pattern of TiO2.
Depending on the periodicity you intend to characterize in your "amorphous" or "crystalline" thin/thick film on amorphous glass substrate I suggest you use XRR, X-ray Reflectivity, an in situ, NDE, real time technique. This method will unequivocally identify the following parameters precisely:
See attached RG discussion for a lot more details for NIST2000SRM.
1um film is more a "thick" film than "thin" relatively. I wonder how the XRR signal would look like in that case and what maximum thicknesses could be resolved. Suggestions are welcome.
Intuitively, I'd think that the crystallinity and Nanostructural character of the film would also depend on the substrate material. So depositing on other foils or surfaces may not duplicate the subject sample.
https://www.researchgate.net/post/What_is_the_best_way_to_interpret_3D_reciprocal_space_data_from_XRD_rocking_curve_analysis2
If it is structure information for the polycrystalline component in the film (1um) that you are interested in, then the interrogation depth may be limited to the surface film by minimizing the incidence angle, GIXRD, grazing incidence XRD. Do keep in mind the larger sampling surface area as a result of the shallow incidence angles.
The whole idea behind XRD methods is to characterize the in situ Nanostructure of the sample, a key feature that has made it one of the most preferred methods for over a century now.
You can try small angle scattering at so you can get the crystallite size of you sample or try other method like optical (transmission curve) I have paper about that if you want I will send to you
What do you want to learn from the XRD? Something about the crystallinity? Then I would follow the previous answers and recommend you to use Grazing Incidence XRD.
But if you want to know the thickness, the density and the rougness, you should do x-ray reflectivity measurements (or ellipsometry). But it is not so trivial to make smooth TiO2 films on SiO2 (it further depends on how smooth your glass is). But it further depends on what you want to make with these films. In my case, I wanted to use them for reflectivity measurements where you need substrates with a very small roughness (1nm) and no curverture over 1 cm.
Dear Gokul,
As you said your films are 1 micron thick. If you are not getting any diffraction from the film there could be a chance that your film is amorphous. Did you performed any post-deposition annealing? I agree what other experts are suggesting that glancing angle will be the best to avoid background signal from substrate. From my experience 1 micron thick film should give some diffraction peaks if they are crystalline. You can also try Raman spectroscopy which might give you more clues about the phase present in your film. You can also try plotting your XRD data intensity in log scale. Sometime it become easier to see low intensity peaks. Will you also tell me how did you measure the thickness of you films?
Nitin
Go with GI XRD that could be useful to you to get diffraction pattern from your deposited areas alone.
If you try with incident angle (2t) of X-ray 1 or 2 degree (in general is is 5 degrees) some extent you can avoid the background signal. Though the intensity of XRD profile may be low or week, you can see the signal only from you material!
Best of luck.
I would suggest to go for wide angle also rather than a grazing angle diffractometry.
1. The film is grown via sputter. So the film is sufficiently thicker to get a XRD pattern at wide angle. The grazing angle XRD is needed only when you are willing to see either the phase of surface material or the film is very very thin.
2. Basically, glass is an amorphous material, which would not generate any XRD pattern. So there is no point to move for grazing angle diffractometry in this case.
Respected Chandan Das Sir,
I have taken PXRD for my thin films which is showing only the amorphous peaks of glass and there is no difference between different materials coated by sputtering process in PXRD.
You can try for grazing angle instead, if the film is very thin.
You can come to a conclusion after finding your film thickness. Also, if the film is amorphous in nature, the pattern will be absent.
I suggest to those that want to post comments, to read the prior comments and not wantonly repeat advise previously posted. Try to add to the knowledge not just mindless regurgitation. Please be respectful and read others' comments too.
Gokul! Have you yet tried GIXRD with your sample that many have already advised you to try? The grazing incidence angle could be used to minimize the penetration (examination) depth in your sample to a small surface layer based in the angle. So you must compute the extinction depth in your sample material. Unless you limit the penetration depth of the X-ray beam, your XRD signal will be predominantly from the amorphous glass substrate. Any weak signal from a possibly crystalline film would be buried in the amorphous halo and difficult to deconvolute.
Do try to use XRR to establish the film thickness and roughness. You will need Bruker LEPTOS or some such tool for modeling your structure in order to extract parameters.
Intuitively, thin film Nanostructure usually duplicates the "parent" substrate Nanostructure. Chances of getting a crystalline film on an amorphous substrate using sputtering techniques would be small, even smaller for epitaxial. Once you have a "buffer layer" to accommodate the lattice mismatch, then the task becomes easier.
Please post some relevant literature examples of this material for the rest of us to get more familiar with your paradigm and make better suggestions to you.
Gokul! "I have taken PXRD for my thin films which is showing only the amorphous peaks"
What was the angle of incidence (Omega) for this measurement? Please post your diffractograms for the best feedback from the expert RG membership.
Mr.Gokul, I`ve studied TiO2-film obtained by activated chemical decomposition of
titanium-organic precursors. The fig.1 shows the film precipitated on different templates, the fig. 2 shows annealing of TiO2 on Cu foil in vaccuum.
The thickness of the films is 100-200nm.
As you can see there are peaks of anatase at heating to 500C and rutile after heating over 500C to 800C.
Hi Anna Mam,
Have you taken Glancing Angle XRD or normal Powder XRD?
I have some questions.
1st. What the purpose of your TiO2 films?
2nd. Can you precipitate TiO2 on foil?
3rd. Can you heat your films?
Answers,
1). My aim of TiO2 coating is to achieve a transparent coating which differs in some properties from glass
2). I can coat the same TiO2 over foil also.
3).Ya mam i can heat the samples upto some 500 C. As we are not maintaining any oxygen pressure while sputtering, some RG experts suggested me to heat it.
1st. I mean what for you make this coating, is it for photocatalytic purpose?
2nd. You cand deposite film on the foil and then carry out XRD of foil+sample.
3rd. I support the point of heating, because it is considered that at temperature below 500C there is only amorphous TiO2.
1. Gokul! Good discussion!
2. What is the expected penetration depth at 0.001o Incidence angle? BTW how did you ensure that the sample was in the beam at that shallow angle?
3. What is your expected film thickness?
4. What about the diffractograms for the substrate without any film?
5. Have you rotated the sample about its surface normal and repeated the diffractograms? To isolate any preferred orientation effects.
6. What is the XRD profile of the fully crystalline material? (from literature or ICCD old JCPDS)
7. Are you aware that you may edit your initial question any time to include relevant factors so that participants can get a good summary of all the facts in a snapshot?
8. Are you also aware that you may increase the number of topics up top to 15? This will increase the exposure to a larger pool of RG expertise with better feedback.
Hi Anna Mam,
1.No mam it is for self cleaning coatings
2.Can I use Al foil or Cu metal sheet instead glass
3.If I use these metal based substrates for coating, on heating do these metals transform to oxide?
I will also get the peaks corresponding to the substrate material with my thin film coating? How to overcome this issue?
Hi, Gokul.
You shouldn't use Al-foil as its peaks are closed to TiO2. Cu-foil is more appropriate substrate.
Dear Dr. Gokul Raja i attach my paper about optical property of SnS thin films
- Badges
- Science method
- Similar topics
- Methodology
- Crystallography
- X-ray Diffraction