Part V SiGe nanowires 115
9.5 Summary & Outlook
Part VI
Appendix
I
Appendix A
Precision of lattice constant determination
The lattice constant of a crystalline material can be determined from the position of the Bragg peak in a diffraction experiment. However, how accurate the peak position can be determined depends on how accurate all relevant parameters, such as the energy of the X-ray source, the precision of the angular movements of the goniometer and a possible misalignment of the centre of rotation (COR) are defined.
A.1 Relevant parameters
Energy
Usually the energy is determined with a reference crystal by comparing the measured Bragg angles with theoretical ones. In this way the energy can be given with an accu-racy up to ∼0.4 eV.
Remark: For beamlines such as ID13 where no motorized detector movement is avail-able and the Bragg peak position is used to calibrate the detector position, the given energy has to be believed or has to be determined with another method (powder diffraction with reference signal in primary beam for example).
Accuracy of angular movements
The accuracy of the angular movements depends on the used goniometer. For the relevant ω and 2θ movements this is usually in the order of 0.0001◦.
Misalignment
If the sample is aligned slightly out of the centre of rotation for example by misaligning the sample at half beam, the measured 2θvalue is incorrect. An exaggerated sketch of this situation is shown in Fig. A.1.
Resolution
Mainly the secondary beam resolution enters which is governed by the accuracy of the detector movements (see angular movements above), the size of the detector in the scattering plane and the distance between sample and detector. For a Maxipix or PIXcel detector a pixel is 55 µm which results in an accuracy of 0.0016 ◦ at a sample-detector distance of 1 m.
Refraction shifts
Refraction changes the actual angles under which the X-ray beam impinges onto and emerges from the probed lattice planes within the material. Additionally the wave-length in the material changes toλ= λn0.
III
Figure A.1: Misalignment of centre of rotation (COR) yields an offsetδin the detector angle 2θ.
Fitting accuracy
How accurate the position of a peak can be fitted depends on the shape and width of the Bragg peak. Heuristic investigations at one of the laboratory machines have shown that the peak position can not be defined better than 2/1000 of the peak width.
A.2 Error propagation in lattice constant determination
The lattice constants parallel and perpendicular to the inplane direction of a layer with cubic crystal structure and tetragonal distortion are given by
a⊥= 2π Q⊥
l (A.1)
ak = 2π Qk
ph2+k2 (A.2)
where Q⊥,k is the position of the Bragg peak in reciprocal space and h, k, and l are the Miller indices for the chosen reflection.
The Gaussian propagation of uncertainties is the effect of the variables uncertainties (or errors) on the uncertainty of a function based on them [132]. Measurement uncertainties propagate into the combination of variables in the function. The uncertainties of the inde-pendent variablesxi of a functionf(xi) are usually given by the standard deviationsσi and the propagation of uncertainties has the following form:
σf2 =X
i
(∂f
∂xi)2σi2
| {z }
σfxi
+cov(xi, xj) (A.3)
The cov(xi, xj) are the correlation terms of the errors of the different parameters.
For the error in lattice constant determination this gives a dependence only on the uncertainty in the Bragg peak determination in Q-space:
σ2a⊥,k=
"
2π Q2⊥,k
q
(h2+k2, l2)
#2
σQ2⊥,k (A.4)
A.2 Error propagation in lattice constant determination V Therefore, the accuracy of the real space parameters mentioned above have to be taken into account in the conversion from real to reciprocal space to determine σQ⊥,k. The conversion formulas within coplanar diffraction are given by
Q⊥= 4π
λ sin(θ) cos(θ−ω) (A.5)
Qk = 4π
λ sin(θ) sin(θ−ω). (A.6)
The accuracy of the angular movements as well as the misalignment uncertainty can be considered to be uncorrelated. The error in the energy might not be uncorrelated to the misalignment and the angular uncertainties due to the way of energy determination at the synchrotron. Nevertheless, these correlations are neglected and a larger uncertainty is as-signed to the energy.
The total error inQ-space is therefor given by σ2Q⊥,k =σQ2E
⊥,k
+σ2Q2θ
⊥,k
+σQ2ω
⊥,k+... (A.7)
where
σQ2E
⊥,k
=
∂Q⊥,k
∂E 2
σ2E, (A.8)
σ2Q2θ
⊥,k
=
∂Q⊥,k
∂2θ 2
σ2θ2 , (A.9)
σQ2ω
⊥,k =
∂Q⊥,k
∂ω 2
σ2ω. (A.10)
A.2.1 Energy uncertainty
With the relation λ= hcE the uncertainty in energy produces the following error:
σQ2E
⊥
= 4π
hcsin(θ) cos(θ−ω) 2
σE2 (A.11)
σQ2E k
= 4π
hcsin(θ) sin(θ−ω) 2
σE2 (A.12)
The energy and its uncertainty have to be given in eV and h and c are Planck’s constant and speed of light, respectively.
A.2.2 Angular uncertainties
Sample angle uncertainty
If the sample is big enough and homogeneous, the misalignment, which results in a change of the illuminated area on the sample, does not have an effect on the sample angle uncertainty.
The error in the sample rotation is then governed by the accuracy of theω-motor movement.
σQ2ω
⊥ = 4π
λ sin(θ) sin(θ−ω) 2
σω2 (A.13)
σ2Qω
k = 4π
λ sin(θ) cos(θ−ω) 2
σω2. (A.14)
Detector angle uncertainty
The uncertainty in the detector angle is governed by several effects: accuracy of the detector-motor movement, detector pixel size and sample misalignment. These errors can be consid-ered to be independent.
The alignment error δ (see Fig. A.1) can be calculated by the trigonometric cosine law cos(δ) = L2+|L−d|2−d2
2L|L−d| (A.15)
withL= (sin(2θ0),cos(2θ0),0) anddis the displacement of the real centre of rotation. δ has its maximum value when d is perpendicular toL and therefor an upper limit can be given with
δ = arctan(d
L) (A.16)
Nevertheless this error is mostly corrected for when the position of a close-by substrate Bragg peak is used as a reference position. Then only the angular difference of the substrate peak and the peak of interest produces an error. This reduces the effective length of the misalignment roughly by a factor of sin(α) where α is the angular difference between the two peaks.
The total error in the detector angle is then given by
σ2θ2 = (δ2+σaccuracy2 +σ2pixelsize) (A.17) For measurements where an analyzer is used theσpixelsizehas to be replaced by the acceptance angle of the analyzer.
The Q-uncertainty resulting from the 2θ uncertainty is then given by σ2Q2θ
⊥
= 2π
λ cos(2θ−ω) 2
σ2θ2 (A.18)
σQ22θ k
= 2π
λ sin(2θ−ω) 2
σ2θ2 . (A.19)
A.2.3 Systematic error due to refraction
Refraction changes the actual angles under which the X-ray beam impinges onto and emerges from the probed lattice planes within the material. Additionally the wavelength in the material changes toλ= λn0. This error can be corrected.
A.2 Error propagation in lattice constant determination VII
Figure A.2: Snell’s law for the case of X-rays, where n2 < n1. The refraction process is described by well known Snell’s law:
n1sin(β1) =n2sin(β2) (A.20) In 3D it is given by
k2 = n1
n2k1−sign(s·k1) n1
n2cos(β2)−cos(β1)
s (A.21)
where
cos(β1) =|s·k1| (A.22)
cos(β2) = s
1− n1
n2 2
(1−cos2(β1)). (A.23)
Using the wavelength in the material the real ω and 2θ can be calculated:
2θ= 2 arcsin
λ|Q|
4π
(A.24)
ω=θ±arccos(s·Q) (A.25)
The deviations ∆ω and ∆2θare in the order of 1 · 10−3 ◦ inω and 2 · 10−3 ◦ in 2θfor high incidence reflections.
A.2.4 Fitting error
The uncertainty in the fitting error depends on several things such as peak shape and width, signal to noise ratio, step-size of the scan etc. Usually a Gaussian peak is fitted into the measured data, even though a Gaussian shape is only valid for the centre of the peak. Since the central part carries the most of the intensity and information on the peak position, a Gaussian shape is nevertheless a good approximation. Usually the scans are chosen in a way that a reasonable signal to noise ratio is ensured. The step width is chosen according to the peak width in the correspondent direction. Studies at our Panalytical machine show, that the position of the peak can be fitted in the order of 2/1000 of the peak width. For
reasonable parameters (high signal to noise ratio and well defined peaks) the error can be estimated not to be higher as
σQfit
⊥,k
= 1 · 10−4 Å−1. (A.26)
A.3 Error propagation in strain determination
The in-plane and out of plane strain of a material with cubic crystal structure and tetragonal distortion is simply given by
εk = ak−abulk abulk
(A.27) ε⊥= a⊥−abulk
abulk (A.28)
whereak,⊥and abulk are the determined in-plane, out of plane and bulk (unstrained) lattice constants, respectively.
Thus following the propagation of uncertainties (Eq. A.3) the error in the strain depends only on the error in lattice constant determination:
σεk,⊥ = ∂εk,⊥
∂ak,⊥
!
σk,⊥ (A.29)
leading to
σεk,⊥ = σk,⊥
abulk (A.30)
A.4 Exemplary uncertainties for different setups IX
A.4 Exemplary uncertainties for different setups
A.4.1 Panalytical MRD, Hybrid Monochromator, PIXCel detector
Energy (eV) 8048.000 σE (eV) 0.40 L (mm) 1000.00000 σaccuracy (◦) 0.00010 COR (dmax) (mm) 0.10000 σfit (Å−1) 0.00020
Table A.1: General parameters which influence the accuracy of the lattice parameter deter-mination. σfit was estimated with 0.0002 Å−1 since the peaks are often determined by hand.
Si (004) Si (224)
k ⊥ k ⊥
ω|2θ(◦) 34.5642 69.1285 79.2776 88.0291
σω(◦) 0.00010
σQω (Å−1) 0.00001 0.00000 0.00001 0.00001
σ2θ(◦) 0.00654
σQθ (Å−1) 0.00013 0.00019 0.00004 0.00023 σQE (Å−1) 0.00000 0.00023 0.00016 0.00023
σfit (Å−1) 0.00020
σQtotal (Å−1) 0.00024 0.00036 0.00026 0.00038
σa (Å) - 0.00042 0.00043 0.00045 σε(%) - 0.00778 0.00796 0.00825
Table A.2: Individual terms contributing to the final precision of the lattice parameter σa
and hence on the strain εk,⊥ at the angular position of the nominal Si (004) and (224) Bragg peaks.
Ge (004) Ge (224)
k ⊥ k ⊥
ω|2θ(◦) 32.9974 65.9947 77.0985 83.6753
σω(◦) 0.00010
σQω (Å−1) 0.00001 0.00000 0.00001 0.00001
σ2θ(◦) 0.00654
σQθ (Å−1) 0.00013 0.00020 0.00003 0.00023 σQE (Å−1) 0.00000 0.00022 0.00016 0.00022
σfit (Å−1) 0.00020
σQtotal (Å−1) 0.00024 0.00036 0.00026 0.00038
σa (Å) - 0.00045 0.00046 0.00048 σε(%) - 0.00835 0.00847 0.00885
Table A.3: Individual terms contributing to the final precision of the lattice parameter σa
and hence on the strain εk,⊥ at the angular position of the nominal Ge (004) and (224) Bragg peaks.
A.4.2 Beamline ID13 @ ESRF, nanofocus-endstation, Maxipix detector
Energy (eV) 15198.000 σE (eV) 3.00 L (mm) 1013.54000 σaccuracy (◦) 0.03000 COR (dmax) (mm) 0.10000
Table A.4: General parameters which influence the accuracy of the lattice parameter determination.
Ge (008) Ge (228)
k ⊥ k ⊥
ω|2θ(◦) 35.2229 70.4457 57.1868 75.4317
σω(◦) 0.03000
σQω (Å−1) 0.00465 0.00000 0.00465 0.00164
σ2θ(◦) 0.03069
σQθ (Å−1) 0.00119 0.00168 0.00065 0.00196 σQE (Å−1) 0.00000 0.00175 0.00062 0.00175
σfit (Å−1) 0.00300
σQtotal (Å−1) 0.00566 0.00386 0.00561 0.00431
σa (Å) 0.00000 0.00246 0.01010 0.00275 σε(percent) 0.00000 0.04347 0.17851 0.04857
Table A.5: Individual terms contributing to the final precision of the lattice parameter σa and hence on the strain εk,⊥ at the angular position of the nominal Si (008) and (228) Bragg peaks.
A.4 Exemplary uncertainties for different setups XI
Ge (004) Ge (117)
k ⊥ k ⊥
ω|2θ(◦) 16.7616 33.5232 42.4098 61.9765
σω(◦) 0.03000
σQω (Å−1) 0.00233 0.00000 0.00407 0.00082
σ2θ(◦) 0.03069
σQθ (Å−1) 0.00059 0.00197 0.00069 0.00194 σQE (Å−1) 0.00000 0.00088 0.00031 0.00153
σfit (Å−1) 0.00300
σQtotal (Å−1) 0.00384 0.00370 0.00511 0.00398
σa (Å) 0.00000 0.00471 0.01842 0.00289 σε(percent) 0.00000 0.08323 0.32555 0.05115
Table A.6: Individual terms contributing to the final precision of the lattice parameter σa
and hence on the strain εk,⊥ at the angular position of the nominal Ge (004) and (117) Bragg peaks.
Acknowledgements
First and foremost I would like to thank Julian Stangl for supervising this thesis and the great support in all belongings. In this respect I also want to thank Günther Bauer and Václav Holý for taking care of me whenever it was needed.
Furthermore, my dearest thanks go to all present and former colleagues of the X-ray group, Dominik Kriegner, Mario Keplinger, Nina Hrauda, Bernhard Mandl, Dorian Ziss, Eugen Wintersberger, Marc Watzinger and Raphael Grifone for their great support and the amazing times we spent together on beamtimes, conferences and all kind of group activities. You all are friends to me rather than colleagues. The same holds for all other former and present members of the OOCE, Elisabeth Lausecker, Alisha Truhlar, Markus Steindl and Thomas Lettner, thank you for the fun in the office.
Many thanks also to the great staff at the semiconductor devision, without whom successful work would not be possible. Susanne Schwind, Fritz Binder, Ernst Vorhauer, Stefan Bräuer and Alma Halilovic, thank you for your support.
A big big thank you goes to Magdalena Schatzl for the everlasting friendship and support in every circumstance.
I also would like to acknowledge the many people involved in the different collaborations:
Within the GREEN Si project special thanks go to Stefano Cecchi, Danny Chrastina and Giovanni Isella for the growth of the samples, Elisabeth Müller for the TEM analysis and Douglas Paul, Antonio Samarelli and Lourdes Ferre Llin for the fabrication and characteri-zation of the devices.
Concerning the magic superlattices I’d like to thank Stefano Cecchi and Giovanni Isella for the idea and the growth of the structures, Mohammad Ahmadpor Monazam for the theoretical calculations and Eleonore Gatti and Fabio Pezolli for the PL investigations.
My gratitude goes to Martin Süess and Andi Wyss for providing the Ge microbridges, the support at the beamtimes and the following never ending teamwork. In this respect I’d also like to thank Ana Diaz for the great support.
Many thanks also to the beamline staff at ID01 and ID13 at the ESRF in Grenoble and P08 at DESY in Hamburg.
Finally, I would like to thank also my dear friends Sylvia Viertlmayr and Katrin Baumgartner for the open ears in all and every belongings and the exhilarating discussions on physics-topics in a non physicists way.
Last but not least I would like to thank my family for the incredible support during my whole life, no matter which decisions I made.
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Curriculum Vitae
Personal Data
Name Tanja Etzelstorfer
Address Römerstr. 23, 4020 Linz, AUSTRIA
Telephone +43 650 4950200
E-Mail tanja.etzelstorfer@gmx.at
Date an place of birth 30.03.1987 in Linz, AUSTRIA grown up in St. Oswald b. Fr.
Education
01/2012 – 08/2015 Doctorate Degree Studies in Technical Sciences Institute of Semiconductor and Solid State Physics Johannes Kepler University Linz, Austria
Major field of study: Technical Physics
Topic of PhD thesis: „X-ray based investigations of semiconductor multilayer and microbridges“
10/2006 – 12/2011 Diploma Degree in Technical Physics
Institute of Semiconductor and Solid State Physics Johannes Kepler University Linz, Austria
Title of diploma thesis: „Structural investigations of nanomaterials for renewable energy applications“
10/2009 – 07/2010 Study abroad in Great Britain Lancaster University, Lancaster, UK
09/2001 – 06/2006 Vocational education and training college Leonding HTBLA Leonding, Austria
Major field of study: Data processing & Organisation
Awards
05/2015 IRIS 2015 Recognition-Prize
environmental prize of the city of Linz
04/2012 Wilhelm-Macke-Recognition-Prizefor outstanding diploma theses of the Wilhelm Macke foundation
Teaching Experience
since summer term 2014 Access to Higher Education Diplomain Physics, JKU Linz since summer term 2012 Practical in X-ray Diffraction, JKU Linz
2009-2011 European Computer Driving Licence(ECDL), BBRZ Linz
Computer Skills
Programming Python, Matlab, C, C++, Java, Fortran
Other Software Latex, Comsol Multiphysics (Finite Element Modelling software), Office, various imaging editing software
Qualifications
Languages German (native), English (fluent)
Personal Interests
Mountaineering, Travelling, Gardening, Music XV
List of publications
T. Etzelstorfer, M.R. Ahmadpor Monazam, S. Cecchi, D. Kriegner, D. Chrastina, E. Gatti, E. Grilli, N. Rosemann, S. Chatterjee, V. Holý, F. Pezzoli, G. Isella, and J. Stangl. Structural investigations of the α12 Si-Ge superstructure. Journal of Applied Crystallography, 48(1):
262–268, Feb 2015. doi: 10.1107/S1600576715000849. URLhttp://dx.doi.org/10.1107/
S1600576715000849
T. Etzelstorfer, M.J. Süess, G.L. Schiefler, V.L.R. Jacques, D. Carbone, D. Chrastina, G. Isella, R. Spolenak, J. Stangl, H. Sigg, and A. Diaz. Scanning X-ray strain microscopy of inhomogeneously strained Ge micro-bridges. Journal of Synchrotron Radiation, 21(1):
111–118, Jan 2014. doi: 10.1107/S1600577513025459. URLhttp://dx.doi.org/10.1107/
S1600577513025459
H.I.T. Hauge, M.A. Verheijen, S. Conesa-Boj, T. Etzelstorfer, M. Watzinger, D. Kriegner, I. Zardo, C. Fasolato, F. Capitani, P. Postorino, S. Kölling, A. Li, S. Assali, J. Stangl, and E.P.A.M. Bakkers. Hexagonal Silicon Realized. Nano Letters, 0(0):null, 2015. doi: 10.1021/
acs.nanolett.5b01939. URLhttp://dx.doi.org/10.1021/acs.nanolett.5b01939. PMID:
26230363
A. Samarelli, L.Ferre Llin, S. Cecchi, D. Chrastina, G. Isella, T. Etzelstorfer, J. Stangl, E.Muller Gubler, J.M.R. Weaver, P. Dobson, and D.J. Paul. Multilayered Ge/SiGe Material in Microfabricated Thermoelectric Modules. Journal of Electronic Materials, 43(10):3838–
3843, 2014. ISSN 0361-5235. doi: 10.1007/s11664-014-3233-z. URL http://dx.doi.org/
10.1007/s11664-014-3233-z
A. Samarelli, L.Ferre Llin, S. Cecchi, D. Chrastina, G. Isella, T. Etzelstorfer, J. Stangl, E.Muller Gubler, J.M.R. Weaver, P. Dobson, and D.J. Paul. Multilayered Ge/SiGe Material in Microfabricated Thermoelectric Modules. Journal of Electronic Materials, 43(10):3838–
3843, 2014. ISSN 0361-5235. doi: 10.1007/s11664-014-3233-z. URL http://dx.doi.org/
10.1007/s11664-014-3233-z
A. Samarelli, L. Ferre Llin, S. Cecchi, J. Frigerio, D. Chrastina, G. Isella, E. Müller Gubler, T. Etzelstorfer, J. Stangl, Y. Zhang, J.M.R. Weaver, P.S. Dobson, and D.J. Paul. Prospects for SiGe thermoelectric generators. Solid-State Electronics, 98(0):70 – 74, 2014. ISSN 0038-1101. doi: http://dx.doi.org/10.1016/j.sse.2014.04.003. URL http://www.sciencedirect.
com/science/article/pii/S0038110114000513. Selected Papers from {ULIS} 2013 Con-ference
A. Samarelli, L. Ferre Llin, S. Cecchi, J. Frigerio, T. Etzelstorfer, E. Müller Gubler, J.n Stangl, D. Chrastina, G. Isella, and D. Paul. (Invited) The Thermoelectric Properties of Ge/SiGe Based Superlattices: from Materials to Energy Harvesting Modules. ECS Trans-actions, 64(6):929–937, 2014. doi: 10.1149/06406.0929ecst. URLhttp://ecst.ecsdl.org/
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content/64/6/929.abstract
S. Cecchi, T. Etzelstorfer, E. Müller, A. Samarelli, L. Ferre Llin, D. Chrastina, G. Isella, J. Stangl, J.M.R. Weaver, P. Dobson, and D.J. Paul. Ge/SiGe Superlattices for Ther-moelectric Devices Grown by Low-Energy Plasma-Enhanced Chemical Vapor Deposition.
Journal of Electronic Materials, 42(7):2030–2034, 2013. ISSN 0361-5235. doi: 10.1007/
s11664-013-2511-5. URLhttp://dx.doi.org/10.1007/s11664-013-2511-5
S. Cecchi, T. Etzelstorfer, E. Müller, A. Samarelli, L. Ferre Llin, D. Chrastina, G. Isella, J. Stangl, and D.J. Paul. Ge/SiGe superlattices for thermoelectric energy conversion de-vices. Journal of Materials Science, 48(7):2829–2835, 2013. ISSN 0022-2461. doi: 10.1007/
s10853-012-6825-0. URLhttp://dx.doi.org/10.1007/s10853-012-6825-0
L. Ferre Llin, A. Samarelli, S. Cecchi, T. Etzelstorfer, E. Müller Gubler, D. Chrastina, G. Isella, J. Stangl, J. M. R. Weaver, P. S. Dobson, and D. J. Paul. The cross-plane ther-moelectric properties of p-Ge/Si_0.5Ge_0.5 superlattices. Applied Physics Letters, 103(14):
143507, 2013. doi: http://dx.doi.org/10.1063/1.4824100. URLhttp://scitation.aip.org/
content/aip/journal/apl/103/14/10.1063/1.4824100
A. Samarelli, L. Ferre Llin, S. Cecchi, J. Frigerio, T. Etzelstorfer, E. Müller, Y. Zhang, J. R.
Watling, D. Chrastina, G. Isella, J. Stangl, J. P. Hague, J. M. R. Weaver, P. Dobson, and D. J.
Paul. The thermoelectric properties of Ge/SiGe modulation doped superlattices. Journal of Applied Physics, 113(23):233704, 2013. doi: http://dx.doi.org/10.1063/1.4811228. URL http://scitation.aip.org/content/aip/journal/jap/113/23/10.1063/1.4811228 D. Chrastina, S. Cecchi, J.P. Hague, J. Frigerio, A. Samarelli, L. Ferre–Llin, D.J. Paul, E. Müller, T. Etzelstorfer, J. Stangl, and G. Isella. Ge/SiGe superlattices for nanostruc-tured thermoelectric modules. Thin Solid Films, 543(0):153 – 156, 2013. ISSN 0040-6090.
doi: http://dx.doi.org/10.1016/j.tsf.2013.01.002. URL http://www.sciencedirect.com/
science/article/pii/S0040609013000473. International Conference NanoSEA (NANOs-tructures {SElf} Assembly) 2012
L. Ferre Llin, A. Samarelli, Y. Zhang, J.M.R. Weaver, P. Dobson, S. Cecchi, D. Chrastina, G. Isella, T. Etzelstorfer, J. Stangl, E.Muller Gubler, and D.J. Paul. Thermal Conductiv-ity Measurement Methods for SiGe Thermoelectric Materials. Journal of Electronic Ma-terials, 42(7):2376–2380, 2013. ISSN 0361-5235. doi: 10.1007/s11664-013-2505-3. URL http://dx.doi.org/10.1007/s11664-013-2505-3
N Hrauda, J J Zhang, H Groiss, T Etzelstorfer, V Holý, G Bauer, C Deiter, O H Seeck, and J Stangl. Strain relief and shape oscillations in site-controlled coherent SiGe islands.
Nanotechnology, 24(33):335707, 2013. URLhttp://stacks.iop.org/0957-4484/24/i=33/
a=335707
N. Hrauda, J. J. Zhang, H. Groiss, J. C. Gerharz, T. Etzelstorfer, J. Stangl, V. Holý, C. Deiter, O. H. Seeck, and G. Bauer. Closely spaced sige barns as stressor structures for strain-enhancement in silicon. Applied Physics Letters, 102(3):032109, 2013. doi: http://
dx.doi.org/10.1063/1.4789507. URL http://scitation.aip.org/content/aip/journal/
apl/102/3/10.1063/1.4789507
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Dominik Kriegner, Simone Assali, Abderrezak Belabbes, Tanja Etzelstorfer, Václav Holý, Tobias Schülli, Friedhelm Bechstedt, Erik P. A. M. Bakkers, Günther Bauer, and Julian Stangl. Unit cell structure of the wurtzite phase of GaP nanowires: X-ray diffraction studies and density functional theory calculations. Phys. Rev. B, 88:115315, Sep 2013. doi: 10.1103/
PhysRevB.88.115315. URL http://link.aps.org/doi/10.1103/PhysRevB.88.115315 D. Kriegner, J.M. Persson, T. Etzelstorfer, D. Jacobsson, J. Wallentin, J.B. Wagner, K. Dep-pert, M.T. Borgström, and J. Stangl. Structural investigation of GaInP nanowires using X-ray diffraction. Thin Solid Films, 543:100 – 105, 2013. ISSN 0040-6090. doi: http:
//dx.doi.org/10.1016/j.tsf.2013.02.112. URL http://www.sciencedirect.com/science/
article/pii/S0040609013003829. International Conference NanoSEA (NANOstructures {SElf} Assembly) 2012
A. Samarelli, L.Ferre Llin, Y. Zhang, J.M.R. Weaver, P. Dobson, S. Cecchi, D. Chrastina, G. Isella, T. Etzelstorfer, J. Stangl, E.Müller Gubler, and D.J. Paul. Power Factor Charac-terization of Ge/SiGe Thermoelectric Superlattices at 300 K. Journal of Electronic Ma-terials, 42(7):1449–1453, 2013. ISSN 0361-5235. doi: 10.1007/s11664-012-2287-z. URL http://dx.doi.org/10.1007/s11664-012-2287-z
D Jacobsson, J M Persson, D Kriegner, T Etzelstorfer, J Wallentin, J B Wagner, J Stangl, L Samuelson, K Deppert, and M T Borgström. Particle-assisted GaxIn1−xP nanowire growth for designed bandgap structures. Nanotechnology, 23(24):245601, 2012. URLhttp:
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