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Mota-Santiago P, Vazquez H, Bierschenk T, Kremer F, Nadzri A, Schauries D, Djurabekova F, Nordlund K, Trautmann C, Mudie S, Ridgway MC, Kluth P. Nanoscale density variations induced by high energy heavy ions in amorphous silicon nitride and silicon dioxide. Nanotechnology 2018; 29:144004. [PMID: 29384134 DOI: 10.1088/1361-6528/aaabdb] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
The cylindrical nanoscale density variations resulting from the interaction of 185 MeV and 2.2 GeV Au ions with 1.0 μm thick amorphous SiN x :H and SiO x :H layers are determined using small angle x-ray scattering measurements. The resulting density profiles resembles an under-dense core surrounded by an over-dense shell with a smooth transition between the two regions, consistent with molecular-dynamics simulations. For amorphous SiN x :H, the density variations show a radius of 4.2 nm with a relative density change three times larger than the value determined for amorphous SiO x :H, with a radius of 5.5 nm. Complementary infrared spectroscopy measurements exhibit a damage cross-section comparable to the core dimensions. The morphology of the density variations results from freezing in the local viscous flow arising from the non-uniform temperature profile in the radial direction of the ion path. The concomitant drop in viscosity mediated by the thermal conductivity appears to be the main driving force rather than the presence of a density anomaly.
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Affiliation(s)
- P Mota-Santiago
- Department of Electronic Materials Engineering, Research School of Physics and Engineering, Australian National University, Canberra ACT 2601, Australia
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Mota–Santiago P, Schauries D, Nadzri A, Vora K, Ridgway MC, Kluth P. Characterization of ion track morphology formed by swift heavy ion irradiation in silicon oxynitride films. EPJ Web of Conferences 2015. [DOI: 10.1051/epjconf/20159100008] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Cobas Acosta R, Muñoz-Pérez S, Cadogan JM, Hutchison W, Ridgway MC. Magnetocaloric effect and temperature coefficient of resistance of La0.85Ag0.15MnO3epitaxial thin films obtained by polymer-assisted deposition. EPJ Web of Conferences 2014. [DOI: 10.1051/epjconf/20147504006] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Karolewski MA, Cavell RG, Gordon RA, Glover CJ, Cheah M, Ridgway MC. Predicting XAFS scattering path cumulants and XAFS spectra for metals (Cu, Ni, Fe, Ti, Au) using molecular dynamics simulations. J Synchrotron Radiat 2013; 20:555-566. [PMID: 23765297 DOI: 10.1107/s0909049513010303] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/01/2013] [Accepted: 04/15/2013] [Indexed: 06/02/2023]
Abstract
The ability of molecular dynamics (MD) simulations to support the analysis of X-ray absorption fine-structure (XAFS) data for metals is evaluated. The low-order cumulants (ΔR, σ(2), C3) for XAFS scattering paths are calculated for the metals Cu, Ni, Fe, Ti and Au at 300 K using 28 interatomic potentials of the embedded-atom method type. The MD cumulant predictions were evaluated within a cumulant expansion XAFS fitting model, using global (path-independent) scaling factors. Direct simulations of the corresponding XAFS spectra, χ(R), are also performed using MD configurational data in combination with the FEFF ab initio code. The cumulant scaling parameters compensate for differences between the real and effective scattering path distributions, and for any errors that might exist in the MD predictions and in the experimental data. The fitted value of ΔR is susceptible to experimental errors and inadvertent lattice thermal expansion in the simulation crystallites. The unadjusted predictions of σ(2) vary in accuracy, but do not show a consistent bias for any metal except Au, for which all potentials overestimate σ(2). The unadjusted C3 predictions produced by different potentials display only order-of-magnitude consistency. The accuracy of direct simulations of χ(R) for a given metal varies among the different potentials. For each of the metals Cu, Ni, Fe and Ti, one or more of the tested potentials was found to provide a reasonable simulation of χ(R). However, none of the potentials tested for Au was sufficiently accurate for this purpose.
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Affiliation(s)
- M A Karolewski
- Department of Chemistry, University of Alberta, Saskatchewan Drive, Edmonton, AB, Canada.
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Ridgway MC, Bierschenk T, Giulian R, Afra B, Rodriguez MD, Araujo LL, Byrne AP, Kirby N, Pakarinen OH, Djurabekova F, Nordlund K, Schleberger M, Osmani O, Medvedev N, Rethfeld B, Kluth P. Tracks and voids in amorphous Ge induced by swift heavy-ion irradiation. Phys Rev Lett 2013; 110:245502. [PMID: 25165936 DOI: 10.1103/physrevlett.110.245502] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/17/2013] [Revised: 05/02/2013] [Indexed: 06/03/2023]
Abstract
Ion tracks formed in amorphous Ge by swift heavy-ion irradiation have been identified with experiment and modeling to yield unambiguous evidence of tracks in an amorphous semiconductor. Their underdense core and overdense shell result from quenched-in radially outward material flow. Following a solid-to-liquid phase transformation, the volume contraction necessary to accommodate the high-density molten phase produces voids, potentially the precursors to porosity, along the ion direction. Their bow-tie shape, reproduced by simulation, results from radially inward resolidification.
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Affiliation(s)
- M C Ridgway
- Research School of Physics and Engineering, Australian National University, Canberra 0200, Australia
| | - T Bierschenk
- Research School of Physics and Engineering, Australian National University, Canberra 0200, Australia
| | - R Giulian
- Research School of Physics and Engineering, Australian National University, Canberra 0200, Australia
| | - B Afra
- Research School of Physics and Engineering, Australian National University, Canberra 0200, Australia
| | - M D Rodriguez
- Research School of Physics and Engineering, Australian National University, Canberra 0200, Australia
| | - L L Araujo
- Research School of Physics and Engineering, Australian National University, Canberra 0200, Australia
| | - A P Byrne
- Research School of Physics and Engineering, Australian National University, Canberra 0200, Australia
| | - N Kirby
- Australian Synchrotron, Clayton 3168, Australia
| | - O H Pakarinen
- Department of Physics and Helsinki Institute of Physics, University of Helsinki, 00014 Helsinki, Finland
| | - F Djurabekova
- Department of Physics and Helsinki Institute of Physics, University of Helsinki, 00014 Helsinki, Finland
| | - K Nordlund
- Department of Physics and Helsinki Institute of Physics, University of Helsinki, 00014 Helsinki, Finland
| | - M Schleberger
- Fakultät für Physik, Universität Duisburg-Essen, 47057 Duisburg, Germany
| | - O Osmani
- Fakultät für Physik, Universität Duisburg-Essen, 47057 Duisburg, Germany and Department of Physics and OPTIMAS Research Center, Technical University of Kaiserslautern, 67663 Kaiserslautern, Germany
| | - N Medvedev
- Department of Physics and OPTIMAS Research Center, Technical University of Kaiserslautern, 67663 Kaiserslautern, Germany
| | - B Rethfeld
- Department of Physics and OPTIMAS Research Center, Technical University of Kaiserslautern, 67663 Kaiserslautern, Germany
| | - P Kluth
- Research School of Physics and Engineering, Australian National University, Canberra 0200, Australia
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Decoster S, Glover CJ, Johannessen B, Giulian R, Sprouster DJ, Kluth P, Araujo LL, Hussain ZS, Schnohr C, Salama H, Kremer F, Temst K, Vantomme A, Ridgway MC. Lift-off protocols for thin films for use in EXAFS experiments. J Synchrotron Radiat 2013; 20:426-432. [PMID: 23592621 DOI: 10.1107/s0909049513005049] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/14/2012] [Accepted: 02/20/2013] [Indexed: 06/02/2023]
Abstract
Lift-off protocols for thin films for improved extended X-ray absorption fine structure (EXAFS) measurements are presented. Using wet chemical etching of the substrate or the interlayer between the thin film and the substrate, stand-alone high-quality micrometer-thin films are obtained. Protocols for the single-crystalline semiconductors GeSi, InGaAs, InGaP, InP and GaAs, the amorphous semiconductors GaAs, GeSi and InP and the dielectric materials SiO2 and Si3N4 are presented. The removal of the substrate and the ability to stack the thin films yield benefits for EXAFS experiments in transmission as well as in fluorescence mode. Several cases are presented where this improved sample preparation procedure results in higher-quality EXAFS data compared with conventional sample preparation methods. This lift-off procedure can also be advantageous for other experimental techniques (e.g. small-angle X-ray scattering) that benefit from removing undesired contributions from the substrate.
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Affiliation(s)
- S Decoster
- Instituut voor Kern- en Stralingsfysica, KU Leuven, Celestijnenlaan 200D, Leuven, Belgium.
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Afra B, Rodriguez MD, Trautmann C, Pakarinen OH, Djurabekova F, Nordlund K, Bierschenk T, Giulian R, Ridgway MC, Rizza G, Kirby N, Toulemonde M, Kluth P. SAXS investigations of the morphology of swift heavy ion tracks in α-quartz. J Phys Condens Matter 2013; 25:045006. [PMID: 23238277 DOI: 10.1088/0953-8984/25/4/045006] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
The morphology of swift heavy ion tracks in crystalline α-quartz was investigated using small angle x-ray scattering (SAXS), molecular dynamics (MD) simulations and transmission electron microscopy. Tracks were generated by irradiation with heavy ions with energies between 27 MeV and 2.2 GeV. The analysis of the SAXS data indicates a density change of the tracks of ~2 ± 1% compared to the surrounding quartz matrix for all irradiation conditions. The track radii only show a weak dependence on the electronic energy loss at values above 17 keV nm(-1), in contrast to values previously reported from Rutherford backscattering spectrometry measurements and expectations from the inelastic thermal spike model. The MD simulations are in good agreement at low energy losses, yet predict larger radii than SAXS at high ion energies. The observed discrepancies are discussed with respect to the formation of a defective halo around an amorphous track core, the existence of high stresses and/or the possible presence of a boiling phase in quartz predicted by the inelastic thermal spike model.
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Affiliation(s)
- B Afra
- Department of Electronic Materials Engineering, Research School of Physics and Engineering, The Australian National University, Canberra ACT 0200, Australia.
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Ridgway MC, Giulian R, Sprouster DJ, Kluth P, Araujo LL, Llewellyn DJ, Byrne AP, Kremer F, Fichtner PFP, Rizza G, Amekura H, Toulemonde M. Role of thermodynamics in the shape transformation of embedded metal nanoparticles induced by swift heavy-ion irradiation. Phys Rev Lett 2011; 106:095505. [PMID: 21405636 DOI: 10.1103/physrevlett.106.095505] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/04/2010] [Indexed: 05/30/2023]
Abstract
Swift heavy-ion irradiation of elemental metal nanoparticles (NPs) embedded in amorphous SiO(2) induces a spherical to rodlike shape transformation with the direction of NP elongation aligned to that of the incident ion. Large, once-spherical NPs become progressively more rodlike while small NPs below a critical diameter do not elongate but dissolve in the matrix. We examine this shape transformation for ten metals under a common irradiation condition to achieve mechanistic insight into the transformation process. Subtle differences are apparent including the saturation of the elongated NP width at a minimum sustainable, metal-specific value. Elongated NPs of lesser width are unstable and subject to vaporization. Furthermore, we demonstrate the elongation process is governed by the formation of a molten ion-track in amorphous SiO(2) such that upon saturation the elongated NP width never exceeds the molten ion-track diameter.
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Affiliation(s)
- M C Ridgway
- Research School of Physics and Engineering, Australian National University, Canberra, Australia
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Abstract
ABSTRACTThe thermally-induced Co/SixGe1-x reaction has been studied for a series of isochronal (25–600°C/20 min) and isothermal (600°C/u-240 min) annealing sequences using Rutherford backscattering spectrometry, transmission electron microscopy and sheet resistance measurements. Annealing at 600°C yields a reacted surface layer comprised of Si-rich CoSixGe1-x, Ge-rich SiyGe1-y and possibly CoSi2, with the two former constituents exhibiting a degree of epitaxial alignment with the substrate. The formation of Co/SiSixGe1-x alloys is discussed in terms of the ternary phase diagram.
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Giulian R, Araujo LL, Kluth P, Sprouster DJ, Schnohr CS, Foran GJ, Ridgway MC. Temperature-dependent EXAFS analysis of embedded Pt nanocrystals. J Phys Condens Matter 2009; 21:155302. [PMID: 21825361 DOI: 10.1088/0953-8984/21/15/155302] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
The vibrational and thermal properties of embedded Pt nanocrystals (NCs) have been investigated with temperature-dependent extended x-ray absorption fine structure (EXAFS) spectroscopy. NCs of diameter 1.8-7.4 nm produced by ion implantation in amorphous SiO(2) were analysed over the temperature range 20-295 K. An increase in Einstein temperature (∼194 K) relative to that of a Pt standard (∼179 K) was evident for the smallest NCs while those larger than ∼2.0 nm exhibited values comparable to bulk material. Similarly, the thermal expansion of interatomic distances was lowest for small NCs. While the amorphous SiO(2) matrix restricted the thermal expansion of interatomic distances, it did not have a significant influence on the mean vibrational frequency of embedded Pt NCs. Instead, the latter was governed by finite-size effects or, specifically, capillary pressure.
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Affiliation(s)
- R Giulian
- Department of Electronic Materials Engineering, Research School of Physics and Engineering, Australian National University, Canberra, ACT 0200, Australia
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Kluth P, Schnohr CS, Pakarinen OH, Djurabekova F, Sprouster DJ, Giulian R, Ridgway MC, Byrne AP, Trautmann C, Cookson DJ, Nordlund K, Toulemonde M. Fine structure in swift heavy ion tracks in amorphous SiO2. Phys Rev Lett 2008; 101:175503. [PMID: 18999762 DOI: 10.1103/physrevlett.101.175503] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/22/2008] [Indexed: 05/27/2023]
Abstract
We report on the observation of a fine structure in ion tracks in amorphous SiO2 using small angle x-ray scattering measurements. Tracks were generated by high energy ion irradiation with Au and Xe between 27 MeV and 1.43 GeV. In agreement with molecular dynamics simulations, the tracks consist of a core characterized by a significant density deficit compared to unirradiated material, surrounded by a high density shell. The structure is consistent with a frozen-in pressure wave originating from the center of the ion track as a result of a thermal spike.
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Affiliation(s)
- P Kluth
- Department of Electronic Materials Engineering, Australian National University, Canberra ACT 0200, Australia.
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Xu Q, Sharp ID, Yuan CW, Yi DO, Liao CY, Glaeser AM, Minor AM, Beeman JW, Ridgway MC, Kluth P, Ager JW, Chrzan DC, Haller EE. Large melting-point hysteresis of Ge nanocrystals embedded in SiO2. Phys Rev Lett 2006; 97:155701. [PMID: 17155336 DOI: 10.1103/physrevlett.97.155701] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/04/2006] [Indexed: 05/12/2023]
Abstract
The melting behavior of Ge nanocrystals embedded within SiO2 is evaluated using in situ transmission electron microscopy. The observed melting-point hysteresis is large (+/-17%) and nearly symmetric about the bulk melting point. This hysteresis is modeled successfully using classical nucleation theory without the need to invoke epitaxy.
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Affiliation(s)
- Q Xu
- Department of Materials Science and Engineering, University of California, Berkeley, California 94720, USA
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Glover CJ, Ridgway MC, Yu KM, Foran GJ, Clerc C, Hansen JL, Nylandsted-Larsen A. Structure and low-temperature thermal relaxation of ion-implanted germanium. J Synchrotron Radiat 2001; 8:773-775. [PMID: 11512927 DOI: 10.1107/s0909049500012620] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/31/2000] [Accepted: 09/12/2000] [Indexed: 05/23/2023]
Abstract
The structure of implantation-induced damage in Ge has been investigated using high resolution extended X-ray absorption fine structure spectroscopy (EXAFS). EXAFS data analysis was performed with the Cumulant Method. For the crystalline-to-amorphous transformation, a progressive increase in bond-length was observed without the presence of an asymmetry in interatomic distance distribution (RDF). Beyond the amorphization threshold the RDF was dose dependent and asymmetric, where the bond-length and asymmetry increased as functions of ion dose. Such an effect was attributed to the formation of three- and five-fold coordinated atoms within the amorphous phase. Low-temperature thermal annealing resulted in structural relaxation of the amorphous phase as evidenced by a reduction in the centroid, asymmetry and width of the RDF, as consistent with a reduction in the fraction of non four-fold coordinated atoms. The results have been compared to other EXAFS studies of amorphous Ge, and it is suggested that the range of bond-lengths reported therein is related to the sample preparation method and state of relaxation.
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Affiliation(s)
- C J Glover
- Research School of Physical Sciences and Engineering, Australian National University, Canberra
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Deenapanray PNK, Hillie KT, Demanet CM, Ridgway MC. Atomic force microscopy and high-resolution RBS investigation of the surface modification of magnetron sputter-etched Si(111) in an argon plasma at different pressures. SURF INTERFACE ANAL 1999. [DOI: 10.1002/(sici)1096-9918(199910)27:10<881::aid-sia644>3.0.co;2-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Schultz PJ, Jagadish C, Ridgway MC, Elliman RG, Williams JS. Crystalline-to-amorphous transition for Si-ion irradiation of Si(100). Phys Rev B Condens Matter 1991; 44:9118-9121. [PMID: 9998888 DOI: 10.1103/physrevb.44.9118] [Citation(s) in RCA: 45] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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