An in situ transmission electron microscopy study of the ion irradiation induced amorphisation of silicon by He and Xe

Edmondson, Philip D.; Abrams, Kerry J.; Hinks, John; Greaves, Graeme; Pawley, Christopher James; Hanif, Imran; Donnelly, S. E.

doi:10.1016/j.scriptamat.2015.11.010

Cited by 16 publications

(20 citation statements)

References 20 publications

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“…As heavier ions typically lead to denser atomic collision cascades and thus faster accumulation of damage, the threshold dpa at which Ge will amorphise under Xe (Z = 131) irradiation is expected to be lower than the value reported for Ge (Z = 73) ions [32], [33].…”

Section: Iib Mechanismsmentioning

confidence: 84%

Effects of temperature on the ion-induced bending of germanium and silicon nanowires

Camara

Hanif

Tunes

et al. 2017

Mater. Res. Express

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Nanowires can be manipulated using an ion beam via a phenomenon known as ion-induced bending (IIB). While the mechanisms behind IIB are still the subject of debate, accumulation of point defects or amorphisation are often cited as possible driving mechanisms. Previous results in the literature on IIB of Ge and Si nanowires have shown that after irradiation the aligned nanowires are fully amorphous. Experiments were recently reported in which crystalline seeds were preserved in otherwise-amorphous ion-beam-bent Si nanowires which then facilitated solid-phase epitaxial growth (SPEG) during subsequent annealing. However, the ion-induced alignment of the nanowires was lost during the SPEG. In this work, in situ ion irradiations in a transmission electron microscope at 400°C and 500°C were performed on Ge and Si nanowires, respectively, to supress amorphisation and the build-up of point defects.Both the Ge and Si nanowires were found to bend during irradiation thus drawing into question the role of mechanisms based on damage accumulation under such conditions. These experiments demonstrate for the first time a simple way of realigning single-crystal Ge and Si nanowires via IIB whilst preserving their crystal structure.

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Section: Iib Mechanismsmentioning

confidence: 84%

Effects of temperature on the ion-induced bending of germanium and silicon nanowires

Camara

Hanif

Tunes

et al. 2017

Mater. Res. Express

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“…The swollen damaged part of the nanowire will be made of a mix of continuous amorphous material (which becomes more and more porous during irradiation), [46]- [48] point defects, extended defects and isolated amorphous pockets when irradiated by an heavy ion irradiation such as xenon. [42], [49], [50] Therefore, this would require computer simulations which could be the subject of further study.…”

Section: Effect Of Damage Distribution On Bending Behaviourmentioning

confidence: 99%

“…However, because of the complexity regarding the state of the damaged region, the ratio Ω at which the bending direction of a germanium nanowire is reversed cannot be expected to remain the same if irradiations are performed with significantly different combinations of ion and energy (even if these achieved the same value of Ω) as the type of defects generated would vary. [42], [49] xenon, such a value would result in the nanowire permanently bending away from the ion beam.…”

Section: Effect Of Damage Distribution On Bending Behaviourmentioning

confidence: 99%

Shape Modification of Germanium Nanowires during Ion Irradiation and Subsequent Solid‐Phase Epitaxial Growth

Camara

Hanif

Tunes

et al. 2018

Adv Materials Inter

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During ion irradiation which is often used for the purposes of band gap engineering, nanostructures can experience a phenomenon known as ion-induced bending (IIB). The mechanisms behind this permanent deformation are the subject of debate. In this work, germanium nanowires are irradiated with 30 or 70 keV xenon ions to induce bending either away from or towards the ion beam. By comparing experimental results with Monte-Carlo calculations, the direction of the bending is found to depend on the damage profile over the cross-section of the nanowire. After irradiation, the nanowires are annealed at temperatures up to 440°C triggering solid-phase epitaxial growth (SPEG) causing further modification to the deformed nanowires. After IIB, it is observed that nanowires which had bent away from the ion beam then straighten during SPEG whilst those which had bent towards the ion beam bend even more. This is attributed to differences in the mechanisms responsible for the ion-beam-induced bending in opposite directions. Thus, the results reported here give insights into the mechanisms causing the IIB of nanowires and demonstrate how to predict the evolution of nanowires under irradiation and annealing. Finally, they show that, under certain conditions, the bending can even be removed via SPEG.

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“…To compare the propensity of different ions to induce amorphization, the threshold displacements per atom (dpa) for amorphization is generally used. [2], [20]. Currently, due to the miniaturisation of transistors it becomes more and more imperative to precisely control the dpa (and the fluence) for complete amorphization, the depth of the amorphous material and the presence of isolated amorphous zones, as these features greatly impact the properties of sub-micron transistors.…”

Section: Introductionmentioning

confidence: 99%

“…It has therefore been proposed that, in such cases, amorphous regions (or pockets) may form directly as a result of single ion impacts and that complete amorphization then results from their accumulation. [1], [2] Whilst this model may be appropriate for heavy ions, the lighter the ion used for irradiation the less likely it is to produce amorphous regions in single impacts. [1], [26] For this reason, a modified version of the heterogeneous model has been introduced where, instead of an amorphous region produced directly by a single ion impact, such a region could be the result of the overlap of damaged regions that result from single ion impacts.…”

Section: Introductionmentioning

confidence: 99%

Understanding amorphization mechanisms using ion irradiation in situ a TEM and 3D damage reconstruction

et al. 2019

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In this work, ion irradiations in-situ of a transmission electron microscope are performed on singlecrystal germanium specimens with either xenon, krypton, argon, neon or helium. Using analysis of selected area diffraction patterns and a custom implementation of the Stopping and Range of Ions in Matter (SRIM) within MATLAB (which allows both the 3D reconstruction of the collision cascades and the calculation of the density of vacancies) the mechanisms behind amorphization are revealed. An intriguing finding regarding the threshold displacements per atom (dpa) required for amorphization results from this study: even though the heavier ions generate more displacements than lighter ions, it is observed that the threshold dpa for amorphization is lower for the krypton-irradiated specimens than for the xenon-irradiated ones. The 3D reconstructions of the collision cascades show that this counter-intuitive observation is the consequence of a heterogeneous amorphization mechanism. Furthermore, it is also shown that such a heterogeneous process occurs even for helium ions, which, on average induce only three recoils per ion in the specimen. It is revealed that at relatively high dpa, the stochastic nature of the collision cascade ensures complete amorphization via the accumulation of large clusters of defects and even amorphous zones generated by single-heliumion strikes.

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An in situ transmission electron microscopy study of the ion irradiation induced amorphisation of silicon by He and Xe

Cited by 16 publications

References 20 publications

Effects of temperature on the ion-induced bending of germanium and silicon nanowires

Effects of temperature on the ion-induced bending of germanium and silicon nanowires

Shape Modification of Germanium Nanowires during Ion Irradiation and Subsequent Solid‐Phase Epitaxial Growth

Understanding amorphization mechanisms using ion irradiation in situ a TEM and 3D damage reconstruction

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