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B Liu - One of the best experts on this subject based on the ideXlab platform.
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proposed correlatIon of glass formatIon ability with critical dosage for the amorphous alloys formed by Ion Beam Mixing
RSC Advances, 2015Co-Authors: M H Yang, B LiuAbstract:A negative correlatIon of glass formatIon ability with the critical dosage, i.e. minimum Ion-dosage, is first proposed for the amorphous alloys formed by Ion Beam Mixing (IBM), i.e. the lower the critical Ion-dosage (Dc) the better the glass formatIon ability (GFA), suggesting that Dc could serve as an indicator to the GFA of these alloys. The correlatIon is not only supported by the results of experiments such as IBM and liquid melt quenching (LMQ), but is also proven to be relevant by thermodynamic calculatIons. The proposal helps to bridge the gap of experimental data between different producing methods, e.g. making it possible to apply the IBM results to designing alloy compositIons when producing metallic glasses by LMQ. The limitatIons and prospects are also presented in the discussIon.
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amorphous phase formatIon in the ni ti ta system studied by thermodynamic calculatIon and Ion Beam Mixing
Intermetallics, 2014Co-Authors: Yilin Wang, T L Wang, B LiuAbstract:Abstract The glass formatIon range of the Ni–Ti–Ta system was predicted by thermodynamic calculatIon based on Miedema's model and Alonso's method. To verify the theoretical predictIon, five sets of Ni–Ti–Ta multilayered films with various compositIons which were located in the predicted glass formatIon range were designed and the Ion Beam Mixing was carried out to synthesize the amorphous alloys in the Ni–Ti–Ta system. It turned out that in all the five films with overall compositIons of Ni72Ti21Ta7, Ni60Ti28Ta12, Ni49Ti34Ta17, Ni42Ti36Ta22, and Ni29Ti46Ta25, amorphous phases were indeed obtained, showing a good agreement between the experimental results and the thermodynamic calculatIon. Besides, it is expected that the Ni42Ti36Ta22 was much more favorable for the amorphous phase formatIon.
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glass forming abilities of the fe ta zr ti alloys studied by thermodynamic calculatIon and Ion Beam Mixing
Applied Surface Science, 2014Co-Authors: B LiuAbstract:Abstract Thermodynamic calculatIon and Ion Beam Mixing experiments were carried out for five sets of multilayered films with compositIons of Fe 40 Ta 20 (Zr x Ti 1 − x ) 40 ( x = 0, 0.25, 0.5, 0.75, 1). The results show that the experimental results agreed well with the predictIon, i.e., unique amorphous phases could be formed in all the five sets of films, and by replacing Ti with appropriate amount of Zr, the glass forming ability of the alloy could be improved. Meanwhile, phase separatIon of amorphous phase was observed in the Fe 40 Ta 20 Zr 40 and other quaternary films. The possible mechanism of the amorphous phase formatIon and separatIon was discussed based on thermodynamic calculatIon and atomic collisIon theory.
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effect of y on the glass forming ability of the fe nb system studied by Ion Beam Mixing
Intermetallics, 2014Co-Authors: Yufeng Wang, B LiuAbstract:Abstract Ion Beam Mixing experiments were carried out to investigate the effect of the Y additIon on the glass forming ability and associated structural phase transformatIons of the Fe–Nb binary metal system. The results show that the additIon of Y could extend the glass forming range of the Fe–Nb system from 25–75 at% Fe to 10–80 at% Fe, yet while the additIon of Y exceeded 42 at%, the glass forming ability would be deteriorated. The effect of Y is considered to be attributed to the competitIon between the big size difference of the component metals and large positive heat of Mixing of Y–Nb.
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synthesis of amorphous alloys and amorphous crystalline composites in ternary ni nb zr system by Ion Beam Mixing
Materials Chemistry and Physics, 2013Co-Authors: S H Liang, B LiuAbstract:Abstract Six sets of Ni–Nb–Zr multilayered films were designed and prepared with the overall compositIons of Ni63Nb28Zr9, Ni48Nb13Zr39, Ni29Nb60Zr11, Ni79Nb12Zr9, Ni31Nb31Zr38, and Ni31Nb11Zr58, and an Ion Beam Mixing experiment was then conducted using 180 keV xenon Ions. It is found that the Ni–Nb–Zr system is a readily glass-forming system, and both fully amorphous alloys and amorphous–crystalline composites could be synthesized. A detailed discussIon was presented for the formatIon mechanism of the amorphous alloys and amorphous–crystalline composites. In additIon, thermodynamic calculatIon predicted the glass-forming ability of the system, which is in good agreement with the IBM results. The experimental results and thermodynamic calculatIon obtained in present study are also supported e.g. by the observatIons of rapid solidificatIon.
T L Wang - One of the best experts on this subject based on the ideXlab platform.
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amorphous phase formatIon in the ni ti ta system studied by thermodynamic calculatIon and Ion Beam Mixing
Intermetallics, 2014Co-Authors: Yilin Wang, T L Wang, B LiuAbstract:Abstract The glass formatIon range of the Ni–Ti–Ta system was predicted by thermodynamic calculatIon based on Miedema's model and Alonso's method. To verify the theoretical predictIon, five sets of Ni–Ti–Ta multilayered films with various compositIons which were located in the predicted glass formatIon range were designed and the Ion Beam Mixing was carried out to synthesize the amorphous alloys in the Ni–Ti–Ta system. It turned out that in all the five films with overall compositIons of Ni72Ti21Ta7, Ni60Ti28Ta12, Ni49Ti34Ta17, Ni42Ti36Ta22, and Ni29Ti46Ta25, amorphous phases were indeed obtained, showing a good agreement between the experimental results and the thermodynamic calculatIon. Besides, it is expected that the Ni42Ti36Ta22 was much more favorable for the amorphous phase formatIon.
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non equilibrium alloy phase formatIon and transformatIon driven by Ion Beam Mixing in the fe hf nb multilayers
Science China-technological Sciences, 2012Co-Authors: T L Wang, N Ding, Y Dai, Xue Bai, Baixin LiuAbstract:In the Ion Beam Mixing experiments, eight Fe-Hf-Nb multilayered films, with overall compositIons of Fe67Hf22Nb11, Fe67Hf11Nb22, Fe54Hf38Nb8, Fe54Hf30Nb16, Fe54Hf11Nb35, Fe25Hf67Nb8, Fe25Hf50Nb25 and Fe25Hf11Nb64, were irradiated by 200 keV xenon Ions to doses ranging from 3×1014 Xe+/cm2 to 7×1015 Xe+/cm2. The results showed that unique amorphous phases were obtained at designed alloy compositIons, falling in the favored glass-forming regIon deduced from three binary metal sub-systems. Interestingly, at some alloy compositIons, the crystal-amorphous-crystal transformatIons were observed back and forth while varying the irradiatIon doses. In additIon, at the alloy compositIon of Fe25Hf67Nb8, a metastable FCC phase was formed through an HCP-FCC structural phase transformatIon and it had a large lattice constant identified to be a=4.51 A. Besides, the formatIon mechanism of non-equilibrium alloy phases was also discussed in terms of thermodynamics of solids and atomic collisIon theory.
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glass forming ability of the binary cu hf system studied by thermodynamic calculatIon and Ion Beam Mixing
Materials Letters, 2010Co-Authors: Y Y Cui, T L Wang, B LiuAbstract:Abstract Based on Miedema's semi-empirical model, a Gibbs free energy diagram is constructed for the Cu–Hf system and shows that the amorphous phase is favored to be formed over 8–94 at.% Hf, which is much broader than the experimentally determined 30–70 at.% Hf. Three Cu–Hf multilayered films were therefore designed with the overall compositIons of Cu 93 Hf 7 , Cu 81 Hf 19 and Cu 23 Hf 77 , respectively, and then an Ion Beam Mixing experiment was conducted using 200 keV xenon Ions to see whether the metallic glass forming range of the Cu–Hf system could be extended beyond the previously reported range. Interestingly, Ion Beam Mixing results show that a uniform amorphous phase can be obtained in the Cu 23 Hf 77 sample and the amorphous phase is also observed to coexist with crystalline Cu in the Cu 81 Hf 19 sample. These results suggest that the metallic glass forming range of the Cu–Hf system could, at least, be extended to 77 at.% Hf, which falls in the range predicted by the Gibbs free energy diagram.
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Ion Beam Mixing to study the metallic glass formatIon of the cu zr system
Materials Letters, 2010Co-Authors: T L Wang, Wengan Wang, W T Huang, B LiuAbstract:Abstract An Ion Beam Mixing experiment for Cu–Zr system was conducted and two supersaturated solid solutIons were observed with compositIons of 16 atom% Zr in Cu and 17 atom% Cu in Zr, respectively, which are much greater than almost nil found from the equilibrium phase diagram of Cu–Zr system. The observatIon indicates that Cu–Zr metallic glasses could possibly be obtained in compositIon range bounded by the two observed solid solubilities, i.e. 16–83 atom% Zr. Besides, a unique Cu 65 Zr 35 metallic glass was obtained by Ion Beam Mixing and its compositIon is very close to the so-called best compositIon referred in the literature.
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non equilibrium alloy formatIon in the ag zr system by Ion Beam Mixing
Journal of Alloys and Compounds, 2009Co-Authors: Y Y Cui, T L Wang, Kaiping Tai, B LiuAbstract:Abstract Based on Miedema's model, a Gibbs free energy diagram was first constructed for the Ag–Zr system and showed that the free energy of the Ag–Zr multilayered films could be higher than that of the corresponding supersaturated solid solutIons and amorphous phase. Ion Beam Mixing with Ag 90 Zr 10 , Ag 48 Zr 52 and Ag 12 Zr 88 multilayered films was then conducted by 200 keV xenon Ions. It was found that an fcc supersaturated solid solutIon, a mixture of fcc and hcp metastable crystalline structures and an hcp supersaturated solid solutIon were formed and that amorphous phases were also observed to coexist with the metastable crystalline structures. The experimental observatIons concerning the non-equilibrium alloy formatIon matched well with the calculated Gibbs free energy diagram.
B.x. Liu - One of the best experts on this subject based on the ideXlab platform.
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atomistic simulatIons to predict favored glass formatIon compositIon and Ion Beam Mixing of nano multiple metal layers to produce ternary amorphous films
Metals, 2018Co-Authors: M H Yang, B.x. Liu, J B LiuAbstract:Based on the framework of long-range empirical formulas, the interatomic potentials were constructed for the Ni-Nb-Mo (fcc-bcc-bcc) and Ni-Zr-Mo (fcc-hcp-bcc) ternary metal systems. Applying the constructed potentials, atomistic simulatIons were performed to predict the energetically favored glass formatIon regIons (GFRs) in the respective compositIon triangles of the systems. In additIon, the amorphizatIon driving forces (ADFs), i.e., the energy differences between the solid solutIons and disordered phases, were computed and appeared to correlate with the so-called glass forming abilities. To verify the atomistic predictIon, Ion Beam Mixing with nano-multiple-metal-layers was carried out to produce ternary amorphous films. The results showed that the compositIon of ternary amorphous films obtained by Ion Beam Mixing all locate inside the GFRs, supporting the predictIons of atomistic simulatIons. Interestingly, the minimum Ion dosage required for amorphizatIon showed a negative correlatIon with the calculated ADF, implying that the predicted amorphizatIon driving force could be an indicator of the glass formatIon ability.
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metastable phase formatIon and transformatIon studied by Ion Mixing and computatIon for the cu zr ni system
Nuclear Instruments & Methods in Physics Research Section B-beam Interactions With Materials and Atoms, 2013Co-Authors: Qianzhi Wang, Y Y Cui, N Ding, B.x. LiuAbstract:Glass-forming ability/range of the Cu–Zr–Ni ternary system was studied by thermodynamic calculatIons and Ion Beam Mixing of multilayered films. Thermodynamic calculatIons located an energetically favored compositIon regIon for metallic glass formatIon, and also characterized the compositIon dependence of the glass-forming ability. Under the guidance of the thermodynamics calculatIons, four sets of nano-sized Cu–Zr–Ni multilayered samples were designed, prepared and then subjected to irradiatIon by 200 keV xenon Ions. It turned out that unique amorphous phases were indeed obtained in the samples Cu21Zr55Ni24 and Cu24Zr45Ni31 that were located in the predicted superior glass-forming ability regIon, while for the Cu33Zr17Ni50 and Cu68Zr19Ni13 samples that fell within the low glass-forming ability regIon, Ion Beam Mixing resulted in the formatIon of amorphous-crystalline dual-phase structures. A brief discussIon was also presented for the formatIon mechanisms of the amorphous phase and the amorphous-crystalline composites.
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Glass formatIon of the Fe–Hf system studied by thermodynamic calculatIon and Ion Beam Mixing
Journal of Alloys and Compounds, 2010Co-Authors: Taowei Wang, Wengan Wang, B.x. LiuAbstract:Abstract For the Fe–Hf system characterized by a negative heat of formatIon, the glass-forming range/ability (GFR/GFA) was studied by thermodynamic calculatIon based on Miedema's model and Alonso's method. It was found that amorphous phase could be formed in a compositIon range of 24–86 atom% Hf and that alloy with compositIon of Fe 58 Hf 42 has the best GFA in the system. Experimentally, Ion Beam Mixing was carried out to synthesize amorphous alloys in the Fe–Hf system. It turned out that in the samples with overall compositIons located in the calculated GFR, amorphous phases were indeed obtained, whereas no amorphous phase was obtained if the overall compositIons were located outside of the predicted regIon favoring for amorphous alloy formatIon, showing a good agreement between the experimental results and the thermodynamic calculatIon.
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metastable phase formatIon in the immiscible cu co system studied by thermodynamic molecular dynamics and ab initio calculatIons together with Ion Beam Mixing
Journal of Physics: Condensed Matter, 2007Co-Authors: H F Yan, Y X Shen, H B Guo, B.x. LiuAbstract:For the equilibrium immiscible Cu?Co system with a positive heat of formatIon of +10?kJ?mol?1, ab initio calculatIons were used to predict the physical properties of the metastable D019 and L12 structures for the Cu75Co25 phases and the D019 structure for the Cu25Co75 alloy. Based on the ab initio calculatIon results, an n-body Cu?Co potential was constructed and proven to be realistic. Applying the constructed Cu?Co potential, molecular dynamics simulatIons predict that the amorphous phase could be obtained at around Cu60Co40 and its atomic distributIon could be inhomogeneous. Experimentally, by using Ion Beam Mixing with 200?keV Xe+ Ions, an amorphous Cu60Co40 phase with inhomogeneous morphology was indeed obtained at a dose of 1 ? 1015?Xe+?cm?2. Increasing the irradiatIon dose to 4 ? 1015?Xe+?cm?2, a mixture of Cu-rich and Co-rich metastable phases was obtained. Besides, a mixture of FCC and HCP structures was observed in the Cu82Co18 multilayered sample and an HCP structure was observed in the Cu26Co74 multilayered sample. It was found that the lattice constants of the FCC and HCP phases determined by diffractIon analysis were quite compatible with those predicted by the ab initio calculatIons.
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icositetrahedral and icosahedral atomic configuratIons observed in the nb ag metallic glasses synthesized by Ion Beam Mixing
Applied Physics Letters, 2006Co-Authors: Kaiping Tai, W S Lai, N Gao, X D Dai, B.x. LiuAbstract:Metallic glasses are obtained in an immiscible Nb–Ag system by Ion Beam Mixing and an atomic configuratIon in the amorphous structure is discovered, i.e., an icositetrahedral ordering, which, together with an icosahedral ordering also observed in the Nb–Ag metallic glasses and in some previously reported systems, helps in formulating a structural spectrum of the amorphous solids. The experimental characterizatIon and atomistic modeling with an ab initio derived Nb–Ag potential demonstrate the significance of structural heredity, i.e., the crystalline structures of the constituent metals play a decisive role in determining the atomic structure of the metallic glasses in the system.
Y Y Cui - One of the best experts on this subject based on the ideXlab platform.
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metastable phase formatIon and transformatIon studied by Ion Mixing and computatIon for the cu zr ni system
Nuclear Instruments & Methods in Physics Research Section B-beam Interactions With Materials and Atoms, 2013Co-Authors: Qianzhi Wang, Y Y Cui, N Ding, B.x. LiuAbstract:Glass-forming ability/range of the Cu–Zr–Ni ternary system was studied by thermodynamic calculatIons and Ion Beam Mixing of multilayered films. Thermodynamic calculatIons located an energetically favored compositIon regIon for metallic glass formatIon, and also characterized the compositIon dependence of the glass-forming ability. Under the guidance of the thermodynamics calculatIons, four sets of nano-sized Cu–Zr–Ni multilayered samples were designed, prepared and then subjected to irradiatIon by 200 keV xenon Ions. It turned out that unique amorphous phases were indeed obtained in the samples Cu21Zr55Ni24 and Cu24Zr45Ni31 that were located in the predicted superior glass-forming ability regIon, while for the Cu33Zr17Ni50 and Cu68Zr19Ni13 samples that fell within the low glass-forming ability regIon, Ion Beam Mixing resulted in the formatIon of amorphous-crystalline dual-phase structures. A brief discussIon was also presented for the formatIon mechanisms of the amorphous phase and the amorphous-crystalline composites.
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compositIon reign favored for the formatIon of cuzral amorphous phases investigated by Ion Beam Mixing
Materials Letters, 2013Co-Authors: X D Bai, Y Y Cui, B LiuAbstract:Abstract Cu 13 Zr 40 Al 47 amorphous phase was obtained in the CuZrAl metallic system by 200 keV xenon Ion Beam Mixing (IBM) in the irradiatIon range of 0.8∼4×10 15 Xe + /cm 2 , clarifying that CuZAl metallic glasses with high concentratIon of Al could be experimentally obtained. We also found the mixtures of amorphous and crystalline phases newly formed in the Cu 7 Zr 14 Al 79 , Cu 16 Zr 7 Al 77 , Cu 27 Zr 22 Al 51 and Cu 84 Zr 9 Al 7 multilayered films. The possible formatIon mechanism of these resultant alloys is discussed in terms of the atomic collisIon theory. These experimental results also provide a substantial support to the results of molecular dynamics simulatIon, which presents a theoretical predictIon of metallic glass favored regIon.
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an intermediate fcc zr state observed in the cu zr ni system upon Ion Beam Mixing
Materials Letters, 2012Co-Authors: Qianzhi Wang, Y Dai, N Ding, Y Y Cui, B LiuAbstract:Abstract A unique face-centered-cubic (fcc) Zr-based solid solutIon was obtained in the Cu 10 Zr 76 Ni 14 multilayered films upon 200 keV xenon Ion Beam Mixing, accompanied by a novel phase transitIon sequence of Cu+Zr+Ni→dual-FCC→FCC→Amorphous while varying the irradiatIon dose. The energetic stability sequence, elastic stability and phonon behaviors derived from first-principle calculatIons jointly evidenced the metastability of fcc Zr from different perspectives. The experimental observatIons and theoretical calculatIons together justify the existence of an intermediate fcc Zr state under non-equilibrium conditIons. Possible formatIon mechanisms for the metastable crystalline phase were also discussed in terms of the atomic collisIon theory.
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formatIon and structure of cu zr al ternary metallic glasses investigated by Ion Beam Mixing and calculatIon
Journal of Alloys and Compounds, 2012Co-Authors: X D Bai, Y Y Cui, N Ding, Y Dai, B LiuAbstract:Abstract The Cu 12.6 Zr 40.5 Al 46.9 and Cu 32.7 Zr 6.7 Al 60.6 amorphous alloys are synthesized in metallic multilayered films by Ion Beam Mixing in the present study. FormatIon mechanism of amorphous phases is discussed in terms of the atomic collisIon theory. To further analyze the structure and compositIon of the obtained Cu–Zr–Al metallic glasses, structure factor S ( q ) is calculated based on the results of molecular dynamics simulatIons. It is found that the Cu 12.6 Zr 40.5 Al 46.9 and Cu 32.7 Zr 6.7 Al 60.6 metallic glasses are mainly consisted of Al–Zr and Al–Al, Cu–Cu amorphous phases, respectively. The calculated results turn out to match well with the experimental observatIon.
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glass forming ability of the binary cu hf system studied by thermodynamic calculatIon and Ion Beam Mixing
Materials Letters, 2010Co-Authors: Y Y Cui, T L Wang, B LiuAbstract:Abstract Based on Miedema's semi-empirical model, a Gibbs free energy diagram is constructed for the Cu–Hf system and shows that the amorphous phase is favored to be formed over 8–94 at.% Hf, which is much broader than the experimentally determined 30–70 at.% Hf. Three Cu–Hf multilayered films were therefore designed with the overall compositIons of Cu 93 Hf 7 , Cu 81 Hf 19 and Cu 23 Hf 77 , respectively, and then an Ion Beam Mixing experiment was conducted using 200 keV xenon Ions to see whether the metallic glass forming range of the Cu–Hf system could be extended beyond the previously reported range. Interestingly, Ion Beam Mixing results show that a uniform amorphous phase can be obtained in the Cu 23 Hf 77 sample and the amorphous phase is also observed to coexist with crystalline Cu in the Cu 81 Hf 19 sample. These results suggest that the metallic glass forming range of the Cu–Hf system could, at least, be extended to 77 at.% Hf, which falls in the range predicted by the Gibbs free energy diagram.
Dominique Bougeard - One of the best experts on this subject based on the ideXlab platform.
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Ion Beam induced atomic Mixing in ge si and sige studied by means of isotope multilayer structures
Materials, 2017Co-Authors: M Radek, B Schmidt, Dominique Bougeard, Bartosz Liedke, L Bischoff, Matthias Voelskow, John Lundsgaard Hansen, Arne Nylandsted Larsen, Roman Bottger, S PrucnalAbstract:Crystalline and preamorphized isotope multilayers are utilized to investigate the dependence of Ion Beam Mixing in silicon (Si), germanium (Ge), and silicon germanium (SiGe) on the atomic structure of the sample, temperature, Ion flux, and electrical doping by the implanted Ions. The magnitude of Mixing is determined by secondary Ion mass spectrometry. Rutherford backscattering spectrometry in channeling geometry, Raman spectroscopy, and transmissIon electron microscopy provide informatIon about the structural state after Ion irradiatIon. Different temperature regimes with characteristic Mixing properties are identified. A disparity in atomic Mixing of Si and Ge becomes evident while SiGe shows an intermediate behavior. Overall, atomic Mixing increases with temperature, and it is stronger in the amorphous than in the crystalline state. Ion-Beam-induced Mixing in Ge shows no dependence on doping by the implanted Ions. In contrast, a doping effect is found in Si at higher temperature. Molecular dynamics simulatIons clearly show that Ion Beam Mixing in Ge is mainly determined by the thermal spike mechanism. In the case of Si thermal spike, Mixing prevails at low temperature whereas Ion Beam-induced enhanced self-diffusIon dominates the atomic Mixing at high temperature. The latter process is attributed to highly mobile Si di-interstitials formed under irradiatIon and during damage annealing.
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temperature dependence of Ion Beam Mixing in crystalline and amorphous germanium isotope multilayer structures
Journal of Applied Physics, 2014Co-Authors: M Radek, H Bracht, M Posselt, B Schmidt, Bartosz Liedke, Dominique BougeardAbstract:Self-atom Mixing induced by 310 keV gallium (Ga) Ion implantatIon in crystalline and preamorphized germanium (Ge) at temperatures between 164 K and 623 K and a dose of 1 × 1015 cm−2 is investigated using isotopic multilayer structures of alternating 70 Ge and nat Ge layers grown by molecular Beam epitaxy. The distributIon of the implanted Ga atoms and the Ion-Beam induced depth-dependent self-atom Mixing was determined by means of secondary Ion mass spectrometry. Three different temperature regimes of self-atom Mixing, i.e., low-, intermediate-, and high-temperature regimes are observed. At temperatures up to 423 K, the Mixing is independent of the initial structure, whereas at 523 K, the interMixing of the preamorphized Ge structure is about twice as high as that of crystalline Ge. At 623 K, the interMixing of the initially amorphous Ge structure is strongly reduced and approaches the Mixing of the crystalline material. The temperature dependence of Ion-Beam Mixing is described by competitive amorphizatIon and recrystallizatIon processes.
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Ion Beam Mixing in crystalline and amorphous germanium isotope multilayers
Journal of Applied Physics, 2011Co-Authors: H Bracht, M Radek, R Kube, S Knebel, M Posselt, B Schmidt, E E Haller, Dominique BougeardAbstract:Gallium (Ga) implantatIon induced self-atom Mixing in crystalline and amorphous germanium (Ge) is investigated utilizing isotopically controlled Ge multilayer structures grown by molecular Beam epitaxy. The distributIon of the Ga Ions and the Ion-Beam induced depth-dependent Mixing of the isotope structure was determined by means of secondary Ion mass spectrometry. Whereas the distributIon of Ga in the crystalline and amorphous Ge is very similar and accurately reproduced by computer simulatIons based on binary collisIon approximatIon (BCA), the Ion-Beam induced self-atom Mixing is found to depend strongly on the state of the Ge structure. The experiments reveal stronger self-atom Mixing in crystalline than in amorphous Ge. Atomistic simulatIons based on BCA reproduce the experimental results only when unphysically low Ge displacement energies are assumed. Analysis of the self-atom Mixing induced by silicon implantatIon confirms the low displacement energy deduced within the BCA approach. This demonstrate...
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Ion Beam Mixing in crystalline and amorphous germanium isotope multilayers
Verhandlungen der Deutschen Physikalischen Gesellschaft, 2011Co-Authors: H Bracht, M Radek, R Kube, S Knebel, M Posselt, B Schmidt, E E Haller, Dominique BougeardAbstract:Gallium (Ga) implantatIon induced self-atom Mixing in crystalline and amorphous germanium (Ge) is investigated utilizing isotopically controlled Ge multilayer structures grown by molecular Beam epitaxy. The distributIon of the Ga Ions and the Ion-Beam induced depth-dependent Mixing of the isotope structure was determined by means of secondary Ion mass spectrometry. Whereas the distributIon of Ga in the crystalline and amorphous Ge is very similar and accurately reproduced by computer simulatIons based on binary collisIon approximatIon (BCA), the Ion-Beam induced self-atom Mixing is found to depend strongly on the state of the Ge structure. The experiments reveal stronger self-atom Mixing in crystalline than in amorphous Ge. Atomistic simulatIons based on BCA reproduce the experimental results only when unphysically low Ge displacement energies are assumed. Analysis of the self-atom Mixing induced by silicon implantatIon confirms the low displacement energy deduced within the BCA approach. This demonstrates that thermal spike Mixing contributes significantly to the overall Mixing of the Ge isotope structures. The disparity observed in the Ion-Beam Mixing efficiency of crystalline and amorphous Ge indicates different dominant Mixing mechanisms. We propose that self-atom Mixing in crystalline Ge is mainly controlled by radiatIon enhanced diffusIon during the early stage of Mixing before the crystalline structure turns amorphous, whereas in an already amorphous state self-atom Mixing is mediated by cooperative diffusIon events.
