Hi,

these are thickness fringes of your layer.  From the separation of these fringes  you can calculate the related thickness. I estimated a thickness of about 12 nm from the blue curve.

For an almost perfect thin epitaxial layer the FWHM of the diffraction peak is also related to the thickness.

Hi,

these are thickness fringes of your layer.  From the separation of these fringes  you can calculate the related thickness. I estimated a thickness of about 12 nm from the blue curve.

For an almost perfect thin epitaxial layer the FWHM of the diffraction peak is also related to the thickness.

I think, all satellite peaks will correspond to the kinematical reflection curves for a perfect crystal. Since this also leads to the formation of a system of pseudoplanes, the explanation of peak splitting within the framework is unjustified. The only reason for distortion of the reflection profile is variation of the scattering power in the depth of the crystal, related to the lattice strain gradient. This leads to a characteristic variation of the planes of X-ray waves reflected from various layers with different crystal lattice strains.

Satellite peaks are observed in the superlattice (thin film structures e.g. InGaAs/GaAs Multilayers andAlGaN/GaN/ZnO )

The main peak is the oth order peak. Both side of the main peak, there are many satellite peaks. These peaks give the value of average lattice constant of superlattice.

We can obtain the thickness of the superlattice structure by fitting the obtained spectra.(similar to XRR)

Paper given below will give more information.

Journal of Crystal Growth 310 (2008) 4904–4907

doi:10.1016/j.jcrysgro.2008.07.071

            You have not marked position of the satellite peaks, their intensity and two-theta difference. However, in my opinion, satellite peaks are observed due to phase difference with the main peak. This occurs by the segregation of the elements during growth and forming of the thin film. The nano crystallite of this segregation have the  alienation longitudinal with the main peak and having similar orientation.   

              The figures provided here have large FWHM and broadness, which reveals that these films have lower crystalliny may be due to the grain boundaries, defects and dislocation density. I would suggest you the composition analysis for these films.

Dear J.F. Woitok,

I've confirm the film thickness by SE and HRTEM

the thickness was ~17nm, which was still much higher than that calculated from XRD fringe(~12nm)

is there some reason?

PS: the thickness calculated from FWHM using scherrer equation was~15nm 

Thanks

From the 2theta position of the AlN peak it can be concluded that your layer is full relaxed. Due to the relaxation state the layer will contain a lot of defects. These will affect the peak width and the modulation of the thickness fringes. For the comparison of the thickness values from different techniques more information about your sample is needed.  Was the AlN grown on a blanket sapphire or any kind of buffer layer? How did you measure the XRD? 

Find attached a picture showing simulations of a full relaxed AlN layer on Sapphire with thickness 15 nm(red) and 12 nm(blue). Please note the log scale.

Excellent discussion! Great feed-back! Delighted to learn :-)

• Huan_Yu_Shih! Please describe the XRD instrumentation used including beam conditioners, slit dimensions, detector type etc. used. What is the difference between the 2 profiles you have shown? Just the scale? Try "Log Scale" as well. Have you recorded a standard (e.g., NIST 2000 SRM) with the same XRD tool? What about the substrate peak? Have you considered including a sapphire peak in your scan range as a reference? Know anything about RSM?
• J.F. Woitok! Thanks for the detailed analyses and simulations. What tools did you employ for these contributions? Your expertise is amply evident. Thanks for sharing! Is there any particular reason these fringes (satellites) would not appear for the NIST 2000 SRM example noted below? How do I go about computing the XRD film thickness for the LaSrCuO4/LaSrAlO4 example if I'm able to provide the RCP (rocking curve profile) in ASCII or Excel format? As noted by you the presence of "buffer layers" would modify strain state significantly and hence the XRD profile.
•  Savan V Katba! Good point. "Satellite Peak" is far too general a terminology and may result from many Nano structural morphologies including the one you have noted. See YouTube example of super-lattice MBE material, similar to that you have noted, using a Panalytical X'Pert HRXRD system and a real time 2D AXIS (Advanced XRD Imaging System). https://www.youtube.com/watch?v=qGG78GKDa7w&index=8&list=PL7032E2DAF1F3941F
• Dattatray Gadkari! Good observations regarding the "large FWHM" of nearly 1.5o for the AlN main peak. In the LaSrCuO4/LaSrAlO4 example the FWHM are only 140-330 Arc Sec. Please note that "super-lattice peak" marked on this image is a misnomer and ought to be deleted. These are thickness/flatness fringes.  I'd be really curious what slits (integrating window) and optics were used to get such large FWHM as 1.5o. Without knowing the instrumental FWHM and profile, interpretation may be tough. I don't necessarily agree with the conclusions without additional information :-)
• BTW besides Bragg Peak Position and FWHM, there are other features of the Bragg Profile (aka RCP - Rocking Curve Profile) that may be used to interpret other Nano structural characteristics such as defect types as well.

Attached is the example of MBE grown 50nm LaSrCuO4 epi on (001) LaSrAlO4 which exhibits similar "satellite peaks" as current AlN/Saphire sample being discussed. Any helpful comments and suggestions would be deeply appreciated.

There seems to be so much more to know than I know presently! It's exciting and not scary how little I know yet :-)

https://www.researchgate.net/post/What_is_the_best_way_to_interpret_REAL_TIME_3D_X_Y_o-2TH_o_ph_ch_reciprocal_space_relative_intensity_data_from_HRXRD_rocking_curve_analyses

https://www.researchgate.net/post/X-ray_Rocking_Curve_Analysis_of_Super-lattice_SL_Epitaxial_Structures_What_are_some_of_your_practical_experiences_with_this_method

https://www.youtube.com/watch?v=qGG78GKDa7w&index=8&list=PL7032E2DAF1F3941F

https://www.flickr.com/photos/85210325@N04/8036406846/

https://www.researchgate.net/post/Is_it_possible_to_determine_the_type_morphology_of_defects_in_single_crystals_by_the_shape_of_the_Bragg_XRD_Rocking_Curve_Profile

http://homepage.ntu.edu.tw/~kcyuan/form/For-Rigaku-Upload_thinfilm.pdf

Hi all!

Have a look on Pendellosung fringes, they might explain what you are observing:

https://en.wikipedia.org/wiki/Dynamical_theory_of_diffraction

All the best!

Just one short comment to those already given: From the intensity of the side fringes, the roughness of the film may be estimated. The fringes only occur if the films are smooth, they are strongly smeared with increasing roughness. See the discussion and the data in:

W. Schlemminger & D. Stark, Thin Solid Films 137 (1986) 49-57

doi: 10.1016/0040-6090(86)90193-8

and

K. Häupl, H.L. Kreuzer and P. Wissmann, Z. Naturforsch. A 39 (1984) 5 

and the attached figure based on those papers. Cheers, Dirk

"I've confirm the film thickness by SE and HRTEM"

Any reason you haven't tried the obvious method, XRR?

"I've confirm the film thickness by SE and HRTEM"

Any reason you have overlooked the obvious method, XRR? Reflectivity!

You may achieve this by acquiring the diffractogram from 0o to 2o + with any of the diffractometers you may have and comparing with numerical simulations :-)

An example of XRR profile with the NIST 2000 SRM is attached below.

https://www.researchgate.net/post/What_depths_can_one_typically_probe_with_XRR_X-ray_Reflectivity_Reflectometery/1

https://www.researchgate.net/post/Can_XRR_X-Ray_Reflectivity_be_implemented_in_the_Topographic_Mode_with_spatial_resolution_over_the_sample_surface_Is_there_value_for_such_analyses

https://www.linkedin.com/pulse/epitaxial-thin-film-nano-structure-characterization-using-ravi-ananth

It is related to the interference of thin films. Also indicates that the interface between sub. and thin film is sharp. you can know the thickness of thin films according to the distance of peaks.

These are pendellosung fringes and can be fitted very easily using the equation in the following paper: "Two-dimensional and three-dimensional vortex lattice dynamics in DyBazCu307-(Y, Pr )Ba2Cu307 coupled heterostructures", published in PHYSICAL REVIEW B VOLUME 50,NUMBER 2, 1 JULY 1994-II,1229. The equation that I am referring to is in section III. Characterization and calibration. 

You can use origin pro to do this fitting. Its very straightforward.If fitted properly, you can get out-of plane lattice constant and the number of unit cells.

Is this it? I've requested a full copy from the authors. I'm keenly interested in this topic:-)

It would be interesting to be able to determine "interface Nano structure" through high order Bragg profiles. I do remember seeing the "pendellosung fringes" or "satellite peaks" on the Bragg profile for a sample of superconducting epitaxial material wafer from BNL.. Data is attached. I intend to reanalyze the data with some new software advantages. I'll post in new discussion.

https://www.researchgate.net/post/Is_it_possible_to_precisely_estimate_the_epitaxial_film_thickness_with_XRD_rocking_curve_analysis_2kW_Power_Sealed_Tube_Source?_tpcectx=profile_questions

https://www.researchgate.net/post/Is_it_possible_to_determine_the_epitaxial_film_thickness_precisely_using_Bragg_XRD_Microscopy?_tpcectx=profile_questions

https://www.flickr.com/photos/85210325@N04/8036412739/

https://www.flickr.com/photos/85210325@N04/8036406846/in/photostream/

Article Two-dimensional and three-dimensional vortex lattice dynamic...

J.F. Woitok!

Does Panalytical offer numerical simulation software equivalent of Bruker LEPTOS?

It would be helpful to simulate the Bragg profile and compute layer thickness and interface characteristics.

 Dear Ravi,

Please see the attachments. The first one is the paper and the second one a simulation that I have done. It's for a perovskite oxide on a SrTiO3 substrate. As you can see the simulation is quite good but i am not sure how one can get the "interface nanostructure", but perhaps its possible. Actually, if u look closely at the fitting, the oscillations closer to the main peak are fitting but those far away are not. Perhaps those are due to the film near the interface? 

Regarding the softwares, they do exist but are limited to semiconductors such as III arsenides, nitrides, phosphides, antimonides. Hope this adds to the discussion. 

Good work Paritosh! What was the XRD equipment, optics, beam size and slit sizes used for the "Data" in red?

Is the software available to download? Got a link?

Rather than rain on Huan-yu Shih's parade, I'll create a new question/project on RG with this data set and then post a link here for those interested in continuing the conversation regarding the analyses of such data sets and the interpretation of the corresponding Nano structural details.

Dear Ravi,

The XRD was measured with a two circle Panalytical X’Pert PRO diffractometer (Co Ka1), Sample was rotating at 5 rpm, I cannot exactly recall the details about beam size and slit size, if I recall it is 10 mm 10 mm and 5 mm.

Not sure I understood your question about the software link? did u mean Origin Pro ? or the commercial software. If it's the latter, sorry I don't have the link.

I think that creating a new question/project is a great idea. I have some other articles/math lab codes that can be used to simulate pendellosung fringes fitting for one epilayer on the substrate or even two epilayers on a substrate, provided they have the same in-plane lattice constant.

Hope such discussion will be helpful and can generate ideas how to implement this program to fitting superlattices diffraction patterns. 

"Sample was rotating at 5 rpm,"? About which axis? A flat sample with epitaxial film rotating? Really?

Who offers the "commercial software"?

Can you simulate the NIST 2000 SRM (004)s with Cu K Alpha 1? Si (001) substrate + Si-Ge 50nm + strained Si top layer 25nm!

https://www.linkedin.com/pulse/epitaxial-thin-film-nano-structure-characterization-using-ravi-ananth?trk=mp-reader-card

https://www.researchgate.net/post/What_is_the_best_way_to_interpret_REAL_TIME_3D_X_Y_o-2TH_o_ph_ch_reciprocal_space_relative_intensity_data_from_HRXRD_rocking_curve_analyses?_tpcectx=profile_questions

Sure send me the data theta-2theta scan ..for that structure and i will try to do fit it