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(Laalo3)0.3(Sr2taalo6)0.7(001) Richard T Single Crystal Perovskites Analyzed Using X-ray Photoelectron Spectroscopy: 4. (LaAlO3)0.3(Sr2TaAlO6)0.7(001) Richard T. Haasch, Eric Breckenfeld, and Lane W. Martin Citation: Surface Science Spectra 21, 112 (2014); doi: 10.1116/11.20140904 View online: http://dx.doi.org/10.1116/11.20140904 View Table of Contents: http://scitation.aip.org/content/avs/journal/sss/21/1?ver=pdfcov Published by the AVS: Science & Technology of Materials, Interfaces, and Processing Articles you may be interested in Single Crystal Rare-earth Scandate Perovskites Analyzed Using X-ray Photoelectron Spectroscopy: 3. GdScO3(110) Surf. Sci. Spectra 21, 149 (2014); 10.1116/11.20140908 Single Crystal Perovskites Analyzed Using X-ray Photoelectron Spectroscopy: 5. NdGaO3(110) Surf. Sci. Spectra 21, 122 (2014); 10.1116/11.20140905 Single Crystal Perovskites Analyzed Using X-ray Photoelectron Spectroscopy: 3. LaAlO3(001) Surf. Sci. Spectra 21, 103 (2014); 10.1116/11.20140903 Single Crystal Perovskites Analyzed Using X-ray Photoelectron Spectroscopy: 2. YAlO3(110) Surf. Sci. Spectra 21, 95 (2014); 10.1116/11.20140902 Single Crystal Perovskites Analyzed Using X-ray Photoelectron Spectroscopy: 1. SrTiO3(001) Surf. Sci. Spectra 21, 87 (2014); 10.1116/11.20140901 Redistribution subject to AVS license or copyright; see http://scitation.aip.org/termsconditions. Download to IP: 73.15.5.18 On: Sun, 18 Jan 2015 23:45:09 Single Crystal Perovskites Analyzed Using Accession #: 01313 X-ray Photoelectron Spectroscopy: 4. Technique: XPS (LaAlO ) (Sr TaAlO ) (001) Host Material: Single crystal 3 0.3 2 6 0.7 (LaAlO3)0.3(Sr2TaAlO6)0.7 Richard T. Haascha) Instrument: Kratos Axis Ultra Department of Materials Science and Engineering and Materials Research Laboratory, University Major Elements in Spectra: La, Sr, of Illinois, Urbana-Champaign Al, Ta, O Eric Breckenfeld Minor Elements in Spectra: C Department of Materials Science and Engineering and Materials Research Laboratory, Published Spectra: 11 University of Illinois, Urbana-Champaign; and Naval Research Laboratory, Washington, DC Spectra in Electronic Record: 11 Lane W. Martin Spectral Category: comparison Department of Materials Science and Engineering and Materials Research Laboratory, University of Illinois, Urbana-Champaign; Department of Materials Science and Engineering, University of California, Berkeley; and Materials Science Division, Lawrence Berkeley National Laboratory (Received 3 October 2014; accepted 4 December 2014; published 29 December 2014) X-ray photoelectron spectroscopy (XPS) was used to analyze a commercially available (LaAlO3)0.3(Sr2TaAlO6)0.7 (001) bulk single crystal. XP spectra were obtained using incident monochromatic Al Ka radiation at 0.83401 nm. A survey spectrum together with La 3d, O 1s, C 1s, Sr 3p, Ta 4d, La 4p, Sr 3d, Al 2s, La 4d, Al 2p, Ta 5p, La 5s, Ta 4f, O 2s, Sr 4p and La 5p core level spectra and the valence band are presented. The spectra indicate the principle core level photoelectron and Auger electron signals and show only minor carbon contamination. Making use of the O 1s, Sr 3d, La 4d, Al 2p Ta 4f lines and neglecting the components related to surface contaminants, XPS quantitative analysis reveals an altered stoichiometry of the air-exposed crystal surface of La0.34Sr0.88Al0.82Ta0.43O3. VC 2014 American Vacuum Society. [http://dx.doi.org/10.1116/11.20140904] Keywords: lanthanum strontium aluminum tantalum oxide; perovskite INTRODUCTION SPECIMEN DESCRIPTION (ACCESSION #01313) Transition metal oxides present an impressive variety of func- Host Material: Single crystal (LaAlO3)0.3(Sr2TaAlO6)0.7 tionality which is not available in more traditional systems CAS Registry #: 272780-20-8 such as group IV and III-V semiconductors or elemental met- als. Among the many possible functionalities are, for instance, Host Material Characteristics: homogeneous; solid; single crys- ferroelectricity (Ref. 1) and magnetism (Ref. 2), colossal mag- tal; dielectric; inorganic compound netoresistance (Ref. 3), and high temperature superconductiv- Chemical Name: Lanthanum strontium aluminum tantalum ity (Ref. 4), with transport character ranging from insulating to oxide semiconducting to metallic. Furthermore, these properties are Source: Crystec, GmbH. Grown by the Czochralski method. extremely sensitive to perturbations from chemistry, structural defects, strain and many other effects and this, in turn, pro- Host Composition: (LaAlO3)0.3(Sr2TaAlO6)0.7 vides the materials engineer a number of routes by which to Form: single crystal engineering new functionalities in this class of materials Structure: cubic Pn3(bar)m mixed perovskite, a = 0.7730 nm (Ref. 5). While even simple oxide systems, such as binary (Ref. 7) oxides, exhibit a broad diversity of properties, it is the complex oxide systems which have received the most attention in recent History & Significance: (LaAlO3)0.3(Sr2TaAlO6)0.7 has been years. In particular, materials possessing the perovskite and widely used as a designed substrate for a number of important substituded perovskite structure (with chemical formula applications. It originally rose to prominence as a competitive ABO3) have been observed to exhibit an incredible variety of substrate for high TC oxide superconductors due to its low functionality and phenomena. Advances in thin film epitaxy, dielectric response, exceptional crystallinity, cubic symmetry, particularly pulsed laser deposition, RF magnetron sputtering, and small lattice constant (Ref. 8). Since then, it has been used and molecular beam epitaxy, have enabled researchers to care- as an epitaxial substrate for ferroelectric materials (Ref. 9), fully tune material properties using epitaxial strain. Such high-quality optoelectronic semiconductors (Ref. 10), and co- approaches have provided an opportunity to apply large biaxial lossal magnetoresistive materials (Ref. 11). In order to gain an strains (as much as several percent in some cases) to nanoscale increased understanding of the surfaces and hetero-interfaces films of various materials which would lead to cracks in bulk of perovskite-based materials, (LaAlO3)0.3(Sr2TaAlO6)0.7 bulk materials under similar values of hydrostatic strain (Ref. 6). single crystal was analyzed using X-ray photoelectron spectroscopy. a)Author to whom correspondence should be addressed. As Received Condition: as grown 112 Surface Science Spectra, Vol. 21, 2014 1055-5269/2014/21(1)/112/10/$30.00 VC 2014 American Vacuum Society Redistribution subject to AVS license or copyright; see http://scitation.aip.org/termsconditions. Download to IP: 73.15.5.18 On: Sun, 18 Jan 2015 23:45:09 Analyzed Region: same as host material Peak Shape and Background Method: Background: Custom Ex Situ Preparation/Mounting: Samples were cleaned ultrasoni- three parameter Tougaard background (Ref. 12), U 4 Tougaard VR (B, C, D, T0 ¼ 0) (Ref. 13), was used. O 1s, C 1s, Sr 3d, La 4d, cally for 5 min each in Formula 409 , methyl alcohol, and 2 2 2 deionized water. Samples were mounted onto the sample Al 2p, Ta 4f: B ¼ 299 eV ,C¼ 542 eV ,D¼ 275 eV . holder using double-sided carbon tape (Pella product number Quantitation Method: Quantification was done using region and 16074). component definitions with CasaXPS version 2.3.15. Sensitivity factors were supplied by Kratos Analytical. Errors In Situ Preparation: none are given as 61 standard deviation. Standard deviations are Pre-Analysis Beam Exposure: less than 2 min; no x-ray degra- calculated by CasaXPS using a Monte Carlo method for deter- dation effects observed mining the error distribution for the computed areas. Charge Control: low energy flood gun/magnetic immersion lens combination, filament current = 1.8A, charge balance = 3V, fil- ament bias = 1V ACKNOWLEDGMENTS Temp. During Analysis: 300 K This work was carried out in the Frederick Seitz Materials Pressure During Analysis: <3  10À7 Pa Research Laboratory Central Research Facilities, University of Illinois. E.B. and L.W.M. acknowledge support from the National Science Foundation under grants DMR - 1124696 and DMR - INSTRUMENT DESCRIPTION 1451219. Manufacturer and Model: Kratos Axis Ultra Analyzer Type: spherical sector REFERENCES Detector: channeltron electron multiplier 1. M. Dawber, K. M. Rabe, and J. F. Scott, Rev. Mod. Phys. 77, Number of Detector Elements: 8 1083 (2005). 2. S. A. Chambers, T. C. Droubay, C. M. Wang, K. M. Rosso, S. INSTRUMENT PARAMETERS COMMON TO ALL SPECTRA M. Heald, D. A. Schwartz, K. R. Kittilstved, and D. R. ᭿ Gamelin, Mater. Today 9, 28 (2006). Spectrometer 3. A. P. Ramirez, J. Phys.: Condens. Matter 9, 8171 (1997). Analyzer Mode: constant pass energy 4. J.-M. G. Chen Langlois, Y. Guo, and W. A. Goddard III, Proc. Throughput (T 5 EN): N ¼ 0 Natl. Acad. Sci. U.S.A. 86, 3447 (1989). 5. D. G. Schlom, L.-Q. Chen, C.-B. Eom, K. M. Rabe, S. K. Excitation Source Window: not specified Streifffer, and J.-M. Triscone, Annu. Rev. Mater. Res. 37, 589 Excitation Source: Al Ka, monochromatic (2007). 6. L. W. Martin and D. G. Schlom, Curr. Opin. Solid State Source Energy: 1486.6 eV Mater. Sci. 16, 199 (2012). Source Strength: 180 W 7. W. Wierzchowski, K. Wieteska, W. Graeff, H. Sakowska, T. Source Beam Size: 2000 lm  2000 lm Łukasiewicz, and M. Pawłowska, Cryst. Res. Technol. 40, 517 (2005). Signal Mode: multichannel direct 8. V. Dusastre, Materials for Sustainable Energy, 2nd ed. ᭿ (Nature Publishing Group, New Jersey, 2011), Vol. 1, p. 321. Geometry 9. D. Y. Wang, Y. Wang, J. Y. Dai, H. L. W. Chan, and C. L. Incident Angle: 54 Choy, J. Electroceram. 16, 587 (2006). Source to Analyzer Angle: 54 10. H. Sakowska, M. Swirkowicz, M. Mazur, T. Lukasiewicz, and A. Witek, Cryst. Res. Technol. 36, 851 (2001). Emission Angle: 0 11. M. K. Srivastava, M. P. Singh, A. Kaur, F. S. Razavi, and H. Specimen Azimuthal Angle: 45 K. Sing, J. Appl. Phys. 110, 123922 (2011). 12. S. Tougaard, Surf. Interface Anal. 25, 137 (1997). Acceptance Angle from Analyzer Axis: 0 13. N. Fairley and A. Carrick, The Casa Cookbook Part 1: Analyzer Angular Acceptance Width: 40  40 Recipes for XPS Data Processing (Acolyte Science, Cheshire, UK, 2005), pp.
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