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

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Abstract

In this work, ion irradiations in-situ of a transmission electron microscope are performed on single-crystal 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-helium-ion strikes.
Original languageEnglish
Article number112838
JournalUltramicroscopy
Volume207
Early online date29 Aug 2019
DOIs
Publication statusPublished - 1 Dec 2019

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Amorphization
Ion bombardment
ion irradiation
Helium
Ions
Transmission electron microscopy
damage
cascades
transmission electron microscopy
Krypton
helium ions
krypton
Xenon
xenon
collisions
Atoms
atoms
ions
thresholds
Neon

Cite this

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title = "Understanding amorphization mechanisms using ion irradiation in situ a TEM and 3D damage reconstruction",
abstract = "In this work, ion irradiations in-situ of a transmission electron microscope are performed on single-crystal 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-helium-ion strikes.",
keywords = "In-situ TEM, Radiation damage, Amorphization mechanisms, Semiconductors, Displacement per atom",
author = "Osmane Camara and Tunes, {Matheus A.} and Graeme Greaves and Mir, {Anamul H.} and Stephen Donnelly and Hinks, {Jonathan A.}",
year = "2019",
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TY - JOUR

T1 - Understanding amorphization mechanisms using ion irradiation in situ a TEM and 3D damage reconstruction

AU - Camara, Osmane

AU - Tunes, Matheus A.

AU - Greaves, Graeme

AU - Mir, Anamul H.

AU - Donnelly, Stephen

AU - Hinks, Jonathan A.

PY - 2019/12/1

Y1 - 2019/12/1

N2 - In this work, ion irradiations in-situ of a transmission electron microscope are performed on single-crystal 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-helium-ion strikes.

AB - In this work, ion irradiations in-situ of a transmission electron microscope are performed on single-crystal 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-helium-ion strikes.

KW - In-situ TEM

KW - Radiation damage

KW - Amorphization mechanisms

KW - Semiconductors

KW - Displacement per atom

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