Dear Bogdan,

you can measure the distance of FFT reflections in camera software, the same way as for electron diffraction pattern. You get distance in reciprocal units and just convert to real units. This value corresponds to certain interplanar distance.

But, ... I don´t believe what you are claiming is possible. First at all, the FFT power image originates from real image. If you have some abberations influencing the HRTEM image (e.g. astigmatism), you get slightly deformed FFT pattern after transformation. This may lead to mistaken conclusion that there is deformations of lattice parameters.

The second, from one FFT pattern you can get lattice constants only of two lattice axis. In order to get all three lattice constants, you need a few FFT pattern from different tilts of sample. The point is to have (100), (010) and (001) reflection on pattern. If I am right, the lattice of AlN is hexagonal and GaN tetragonal, for which a=b and differ in c. It is still possible that you were lucky and have (100) or (010) reflection together with (001) on the attached FFT pattern.

Dear Vladimír!

Thank you for your answer to my question. GaN and FFT have a hexagonal crystal structure. At the moment I'm interested in the parameter from the hexagonal crystal lattice. Unfortunately, I do not have the microscope software and all the calculations I'm doing in Python and ImageJ. But I have a TEM image in dm3 format.

As far as I was able to figure it out, I need to determine the interplanar distance d from the BFP results. And the lattice parameter c = 1 / d (I hope I'm right). But how to determine d I can not yet understand.

Can you tell me how to get out of this situation?

Dear Bogdan,

do you have HRTEM image (not FFT) in dm3 or dm4 file format? I´ll try to help you.

Dear Vladimír!

Thank you for your response to the call for help. I attached the image file. But I would very much like to learn how to determine the parameters of the crystal lattice from the TEM images.

Hi, there is a whole literature on what is deemed 'strain mapping', i.e. measuring the local  changes in lattice parameters and deducing the underlying chemical changes indirectly. Most of the papers related to this you will find in the journal Ultramicroscopy. Let me know if you need more details to help you start your search. 

Mr. Thomas!

Thanks for the help! Can you recommend with what works in this journal you can start studying my question?

Hi, just did a small literature survey and found 60 articles by authors I know on this topic from the last 20 years. Here it is. I suggest you start reading from the bottom.  

FN Clarivate Analytics Web of Science

VR 1.0

PT J

AU Cooper, D

Bernier, N

Rouviere, JL

Wang, YY

Weng, WH

Madan, A

Mochizuki, S

Jagannathan, H

AF Cooper, David

Bernier, Nicolas

Rouviere, Jean-Luc

Wang, Yun-Yu

Weng, Weihao

Madan, Anita

Mochizuki, Shogo

Jagannathan, Hemanth

TI High-precision deformation mapping in finFET transistors with two

nanometre spatial resolution by precession electron diffraction

SO APPLIED PHYSICS LETTERS

AB Precession electron diffraction has been used to systematically measure the deformation in Si/SiGe blanket films and patterned finFET test structures grown on silicon-on-insulator type wafers. Deformation maps have been obtained with a spatial resolution of 2.0 nm and a precision of ± 0.025%. The measured deformation by precession diffraction for the blanket films has been validated by comparison to energy dispersive x-ray spectrometry, X-Ray diffraction, and finite element simulations. We show that although the blanket films remain biaxially strained, the patterned fin structures are fully relaxed in the crystallographic planes that have been investigated. We demonstrate that precession diffraction is a viable deformation mapping technique that can be used to provide useful studies of state-of-the-art electronic devices. Published by AIP Publishing.

SN 0003-6951

EI 1077-3118

PD MAY 29

PY 2017

VL 110

IS 22

AR 223109

DI 10.1063/1.4983124

UT WOS:000403341300054

ER

PT J

AU Barcena-Gonzalez, G

Guerrero-Lebrero, MP

Guerrero, E

Fernandez-Reyes, D

Gonzalez, D

Mayoral, A

Utrilla, AD

Ulloa, JM

Galindo, PL

AF Barcena-Gonzalez, G.

Guerrero-Lebrero, M. P.

Guerrero, E.

Fernandez-Reyes, D.

Gonzalez, D.

Mayoral, A.

Utrilla, A. D.

Ulloa, J. M.

Galindo, P. L.

TI Strain mapping accuracy improvement using super-resolution techniques

SO JOURNAL OF MICROSCOPY

AB Super-resolution (SR) software-based techniques aim at generating a final image by combining several noisy frames with lower resolution from the same scene. A comparative study on high-resolution high-angle annular dark field images of InAs/GaAs QDs has been carried out in order to evaluate the performance of the SR technique. The obtained SR images present enhanced resolution and higher signal-to-noise (SNR) ratio and sharpness regarding the experimental images. In addition, SR is also applied in the field of strain analysis using digital image processing applications such as geometrical phase analysis and peak pairs analysis. The precision of the strain mappings can be improved when SR methodologies are applied to experimental images.

OI Gonzalez Robledo, David/0000-0001-6879-444X; Mayoral,

Alvaro/0000-0002-5229-2717

SN 0022-2720

EI 1365-2818

PD APR

PY 2016

VL 262

IS 1

BP 50

EP 58

DI 10.1111/jmi.12341

UT WOS:000372994800006

PM 26501744

ER

PT J

AU Cooper, D

Denneulin, T

Bernier, N

Beche, A

Rouviere, JL

AF Cooper, David

Denneulin, Thibaud

Bernier, Nicolas

Beche, Armand

Rouviere, Jean-Luc

TI Strain mapping of semiconductor specimens with nm-scale resolution in a

transmission electron microscope

SO MICRON

AB The last few years have seen a great deal of progress in the development of transmission electron microscopy based techniques for strain mapping. New techniques have appeared such as dark field electron holography and nanobeam diffraction and better known ones such as geometrical phase analysis have been improved by using aberration corrected ultra-stable modern electron microscopes. In this paper we apply dark field electron holography, the geometrical phase analysis of high angle annular dark field scanning transmission electron microscopy images, nanobeam diffraction and precession diffraction, all performed at the state-of-the-art to five different types of semiconductor samples. These include a simple calibration structure comprising 10-nm-thick SiGe layers to benchmark the techniques. A SiGe recessed source and drain device has been examined in order to test their capabilities on 2D structures. Devices that have.been strained using a nitride stressor have been examined to test the sensitivity of the different techniques when applied to systems containing low values of deformation. To test the techniques on modern semiconductors, an electrically tested device grown on a SOI wafer has been examined. Finally a GaN/AlN superlattice was tested in order to assess the different methods of measuring deformation on specimens that do not have a perfect crystalline structure. The different deformation mapping techniques have been compared to one another and the strengths and weaknesses of each are discussed. (C) 2015 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

RI Cooper, David/E-5659-2011

OI Beche, Armand/0000-0002-8004-4593

SN 0968-4328

PD JAN

PY 2016

VL 80

BP 145

EP 165

DI 10.1016/j.micron.2015.09.001

UT WOS:000366770100018

PM 26606463

ER

PT J

AU Cooper, D

Bernier, N

Rouviere, JL

AF Cooper, David

Bernier, Nicolas

Rouviere, Jean-Luc

TI Combining 2 nm Spatial Resolution and 0.02% Precision for Deformation

Mapping of Semiconductor Specimens in a Transmission Electron Microscope

by Precession Electron Diffraction

SO NANO LETTERS

AB Precession electron diffraction has been used to provide accurate deformation maps of a device structure showing that this technique can provide a spatial resolution of better than 2 nm and a precision of better than 0.02%. The deformation maps have been fitted to simulations that account for thin specimen relaxation. By combining the experimental deformation maps and simulations, we have been able to separate the effects of the stressor and recessed sources and drains and show that the Si3N4 stressor increases the in-plane deformation in the silicon channel from 0.92 to 1.52 ± 0.02%. In addition, the stress in the deposited Si3N4 film has been calculated from the simulations, which is an important parameter for device design.

RI Cooper, David/E-5659-2011

SN 1530-6984

EI 1530-6992

PD AUG

PY 2015

VL 15

IS 8

BP 5289

EP 5294

DI 10.1021/acs.nanolett.5b01614

UT WOS:000359613700066

PM 26218789

ER

PT J

AU Cooper, D

Bernier, N

Rouviere, JL

AF Cooper, David

Bernier, Nicolas

Rouviere, Jean-Luc

GP IEEE

TI Field mapping of semiconductor devices in a transmission electron

microscope with nanometre scale resolution by off-axis electron

holography and precession electron diffraction

SO 2015 IEEE 15TH INTERNATIONAL CONFERENCE ON NANOTECHNOLOGY (IEEE-NANO)

CT IEEE NANO 2015 15th INTERNATIONAL CONFERENCE ON NANOTECHNOLOGY

CY JUL 27-30, 2015

CL ROME, ITALY

SP Univ di Roma, SAPIENZA UNIV DI ROMA, IEEE, IEEE NANO, USN DEPT OF THE NAVY SCI & TECHNOL, ISTITUTO ITALIANO DI TECNOLOGIA, CAMBRIDGE UNIV PRESS, Centro Studi e Documentazione sulla Sensoristica, FEI, Nanoscale Horizons, UNIV NOTRE DAME

AB It is necessary to understand the distribution of the electrostatic potentials and strain fields in semiconductor devices in order to improve their performance. In this paper we will present results showing active dopant mapping that have been obtained on state-of-the-art devices obtained by off-axis electron holography. We will also present a range of different techniques that can be used to map the strain in these devices with nm-scale resolution.

BN 978-1-4673-8155-0

PY 2015

BP 777

EP 780

UT WOS:000380515200105

ER

PT J

AU Javon, E

Lubk, A

Cours, R

Reboh, S

Cherkashin, N

Houdellier, F

Gatel, C

Hytch, MJ

AF Javon, E.

Lubk, A.

Cours, R.

Reboh, S.

Cherkashin, N.

Houdellier, F.

Gatel, C.

Hytch, M. J.

TI Dynamical effects in strain measurements by dark-field electron

holography

SO ULTRAMICROSCOPY

AB Here, we study the effect of dynamic scattering on the projected geometric phase and strain maps reconstructed using dark-field electron holography (DFEH) for non-uniformly strained crystals. The investigated structure consists of a {SiGe/Si} superlattice grown on a (001)-Si substrate. The three dimensional strain held within the thin TEM lamella is modelled by the finite element method. The observed projected strain is simulated in two ways by multiplying the strain at each depth in the crystal by a weighting function determined from a recently developed analytical two-beam dynamical theory, and by simply taking the average value. We demonstrate that the experimental results need to be understood in terms of the dynamical theory and good agreement is found between the experimental and simulated results. Discrepancies do remain for certain cases and are likely to be from an imprecision in the actual two-beam diffraction conditions, notably the deviation parameter, and points to limitations in the 2-beam approximation. Finally, a route towards a 3D reconstruction of strain fields is proposed. (C) 2014 Elsevier B.V. All rights reserved.

RI Gatel, Christophe/F-6046-2014

OI Gatel, Christophe/0000-0001-5549-7008; Cherkashin,

Nikolay/0000-0002-0322-0864

SN 0304-3991

EI 1879-2723

PD DEC

PY 2014

VL 147

BP 70

EP 85

DI 10.1016/j.ultramic.2014.06.005

UT WOS:000343157400009

PM 25062040

ER

PT J

AU Vigouroux, MP

Delaye, V

Bernier, N

Cipro, R

Lafond, D

Audoit, G

Baron, T

Rouviere, JL

Martin, M

Chenevier, B

Bertin, F

AF Vigouroux, M. P.

Delaye, V.

Bernier, N.

Cipro, R.

Lafond, D.

Audoit, G.

Baron, T.

Rouviere, J. L.

Martin, M.

Chenevier, B.

Bertin, F.

TI Strain mapping at the nanoscale using precession electron diffraction in

transmission electron microscope with off axis camera

SO APPLIED PHYSICS LETTERS

AB Precession electron diffraction is an efficient technique to measure strain in nanostructures by precessing the electron beam, while maintaining a few nanometre probe size. Here, we show that an advanced diffraction pattern treatment allows reproducible and precise strain measurements to be obtained using a default 512 x 512 DigiSTAR off-axis camera both in advanced or non-corrected transmission electron microscopes. This treatment consists in both projective geometry correction of diffraction pattern distortions and strain Delaunay triangulation based analysis. Precision in the strain measurement is improved and reached 2.7 x 10(-4) with a probe size approaching 4.2 nm in diameter. This method is applied to the study of the strain state in InGaAs quantum-well (QW) devices elaborated on Si substrate. Results show that the GaAs/Si mismatch does not induce in-plane strain fluctuations in the InGaAs QW region. (C) 2014 AIP Publishing LLC.

SN 0003-6951

EI 1077-3118

PD NOV 10

PY 2014

VL 105

IS 19

AR 191906

DI 10.1063/1.4901435

UT WOS:000345216100037

ER

PT J

AU Denneulin, T

Cooper, D

Rouviere, JL

AF Denneulin, T.

Cooper, D.

Rouviere, J. L.

TI Practical aspects of strain measurement in thin SiGe layers by (004)

dark-field electron holography in Lorentz mode

SO MICRON

AB Dark-field electron holography (DFEH) is a powerful transmission electron microscopy technique for mapping strain with nanometer resolution and high precision. However the technique can be difficult to set up if some practical steps are not respected. In this article, several measurements were performed on thin Si(i-x)Gex layers using (004) DFEH in Lorentz mode. Different practical aspects are discussed such as sample preparation, reconstruction of the holograms and interpretation of the strain maps in terms of sensitivity and accuracy. It was shown that the measurements are not significantly dependent on the preparation tool. Good results can be obtained using both FIB and mechanical polishing. Usually the most important aspect is a precise control of the thickness of the sample. A problem when reconstructing (0 0 4) dark-field holograms is the relatively high phase gradient that characterises the strained regions. It can be difficult to perform reconstructions with high sensitivity in both strained and unstrained regions. Here we introduce simple methods to minimise the noise in the different regions using a specific mask shape in Fourier space or by combining several reconstructions. As a test, DFEH was applied to the characterization of eight Si(1-x)Gex samples with different Ge concentrations. The sensitivity of the strain measured in the layers varies between 0.08% and 0.03% for spatial resolutions of 3.5-7 nm. The results were also compared to finite element mechanical simulations. A good accuracy of ± 0.1% between experiment and simulation was obtained for strains up to 1.5% and ± 0.25% for strains up to 2.5%. (C) 2014 Elsevier Ltd. All rights reserved.

RI Cooper, David/E-5659-2011

SN 0968-4328

PD JUL

PY 2014

VL 62

BP 52

EP 65

DI 10.1016/j.micron.2014.02.017

UT WOS:000336711900007

PM 24811992

ER

PT J

AU Norris, DJ

Qiu, Y

Dobbie, A

Myronov, M

Walther, T

AF Norris, D. J.

Qiu, Y.

Dobbie, A.

Myronov, M.

Walther, T.

TI Similarity of Stranski-Krastanow growth of Ge/Si and SiGe/Si (001)

SO JOURNAL OF APPLIED PHYSICS

AB This study investigates the onset of islanding (Stranski-Krastanow transition) in strained pure germanium (Ge) and dilute silicon-germanium (SiGe) alloy layers grown by chemical vapour deposition on Si(001) substrates. Integration of compositional profiles is compared to a novel method for quantification of X-ray maps acquired in cross-sectional scanning transmission electron microscopy, together with simulations of surface segregation of Ge. We show that Si1-xGex alloys for germanium concentrations x

Dear Bogdan, 

I am guessing you have some orientation information about your image, that is the zone axis of the HRTEM image that will help you at the start.

Very practically before digging in the literature Thomas suggested, you should "solve" your FFT by indexing the reflections. Do not forget FFT is not an electron diffraction pattern and forbidden reflections can show up. Also, you got the FFT from the whole image or from a specific area? Both GaN and AlN reflections will be on the FFT and will be very close to each other, so you need to pay abit more attention to your measurements. You can also measure directly on the HRTEM image.

What you need to calculate the lattice parameters are the (0001) planes to give you the c and the (1-100) planes to give you the a [d(1-100)=a√(3/2)]. But since you have a superlattice structure it will be much more helpful to do your initial measurements in an area that it might be known to get as a reference (e.g. a buffer/nucleation layer or on the interface with the substrate).

You can also use the centre of the thicker layers you have, avoiding the interfaces and see how close you are with the bulk values. Lattice strain mapping techniques use a reference are according to which the lattice variations are measured. The ideal would be to have somewhere in your structure a relatively thicker layer of either GaN or AlN abit away from the superlattice. 

The literature suggested above will help you quite a lot.

Good luck!!!