On 2 n 2D M Mate terials & s & Thei heir Defects ects under electron irradiatjon Jani K ni Kotakoski Faculty of Physics, University of Vienna, Austria htup:/ /dim.univie.ac.at/ jani.kotakoski@univie.ac.at Conference on Physics of Defects in Solids: Quantum Mechanics Meets Topology 9.–13.7.2018 @ ICTP, Trieste, Italy
2D Materials Xia et al., Nat. Photon. 8, 899–907 (2014) Nature 499, 419 (2013) MoS2 Nan et al., ACS Nano 8, 5738 (2014) Tsen et al., Science 336, 1143 (2012) González-Herrero et al., Science 352, 437 (2016)
Transmission Electron Microscopy U. Ludacka, FEI Titan 80-300 @ Vienna Jinschek, Chem. Commun. 50, 2696-2706 (2014)
Nion UltraSTEM 100 @ Vienna Krivanek et al., Ultramicroscopy 108, 179 (2008)
Nion UltraSTEM 100 @ Vienna Pennycook et al., MRS Bulletjn 31, 36 (2006)
Krivanek et al., Nature 464, 571 (2010) JK et al., Nat. Commun. 5, 4991 (2014) Susi, JK, et al. ,2D Mater. 4, 021013 (2017) Ramasse et al, Nano Letu. 13, 4989 (2013)
Electron Beam Efgects in the (S)TEM excitatjons & knock-on chemical efgects ionizatjon H O H O OH Characteristjc cross sectjons and tjme scales for carbon @ 100 kV Kno nock-on dyna namics Ioniza zatj tjon Plasmons cross sectjon: < 1 barn cross sectjon: 10 6 barn cross sectjon: 10 6 barn tjme scale: 10 -15 s tjme scale: 10 -15 s tjme scale: 10 -13 s Phonons ns (elastj stjc collision) Core hole Beam Current: 30 pA cross sectjon: 10 6 barn cross sectjon: 10 4 barn ca. 1 e- / nm 2 / 10 -9 s tjme scale: 10 -12 s tjme scale: 10 -14 s Egerton, Ultramicroscopy 127, 100–108 (2013), Brühwiler et al., Phys. Rev. Letu. 74, 614–617 (1995), Yan et al., Nature Photon. 7, 394–399 (2013), Kang et al., Phys. Rev. B 81, 165405 (2010), Banhart, Rep. Prog. Phys. 62, 1181 (1999), Cossletu, J. Microsc. 113, 113-129 (1978)
Knock-On Process Banhart, Rep. Prog. Phys. 62, 1181 (1999) Conservatjon of energy Conservatjon of momentum Maximum energy transfer occurs for the back scatuering electron and yields Electron energy: eU Initjal velocity of the nucleus or for v = 0
m : 0.51 MeV/c 2 M : Z x 931.49 MeV/c 2 70 Velocity here from kinetjc Carbon-12 theory: 60 Carbon-13 50 Betuer, phonon DOS: Tmax (eV) 40 30 6 20 C 10 Carbon 12, 13.01 0 50 100 150 200 250 300 U (kV) Susi, …, JK, Nat. Commun. 7, 13040 (2016)
Graphene @ 90 kV, TEM Meyer, JK et al., Phys. Rev. Letu. (2012)
Graphene @ 95 kV, STEM Susi, …, JK, Nat. Commun. 7, 13040 (2016)
Displacement Cross Sectjon Nucleus: Q 2 = Z Coulomb Interactjon: Electron: Q 1 = 1 Rutherford scatuering: (valid for charges at low energies) Extended for spin and relatjvistjc electrons by Motu & approximated by McKinley and Feshbach : Electron scatuering angle Using one gets Energy of nucleus afuer scatuering Assuming isotropic displacement threshold E d and integratjng over T > E d leads to: See: Zobelli et al., Phys. Rev. B 75, 245402 (2007) McKinley and H. Feshbach, Phys. Rev. 74, 1759 (1948)
Theory vs. experiment 20 0.25 18 eV 0.20 15 Cross sectjon (barn) Cross sectjon (barn) 22 eV 0.15 18 eV 22 eV 10 0.10 Experiment 5 0.05 Experiment 0.00 0 80 100 120 140 160 180 200 75 80 85 90 95 100 105 110 115 Electron energy (keV) Electron energy (keV) Meyer, JK, et al., Phys. Rev. Letu. 108, 196102 (2012)
Extended model: Velocity distributjon of nuclei Susi, …, JK, Nat. Commun. 7, 13040 (2016)
Sub-threshold Knock-On Efgects Dynamical process due to an impact on one atom Stone-Wales „Flower defect“ Divacancy JK et al., Phys. Rev. B 83, 245420 (2011) — Susi, …, JK, 2D Mater. 4, 042004 (2017) Kurasch, JK, et al., Nano Letu. 12, 3168 (2012) — JK et al., Nat. Commun. 5, 4991 (2014)
From Single- to Multjvacancies @ 100 kV Kotakoski et al., Phys. Rev. Letu. 106, 105505 (2011) & Kotakoski et al., Phys. Rev. B 89, 201406 (2014)
… and to Amorphous 2D Carbon @ 100 kV Kotakoski et al., Phys. Rev. Letu. 106, 105505 (2011) & Eder, JK et al., Sci. Rep. 4, 4060 (2014)
Impurity Atom Dynamics
Observed dynamics Susi, …, JK, 2D Mater. 4, 042004 (2017) Susi, JK, et al. Phys. Rev. Letu. 113, 115501 (2014), Yang et al., Angewandte Chemie 126, 9054 (2014), Lee et al., Nature 4, 1650 (2013), Lin et al., Nano Letuers 15, 74087413 (2015), Kepaptsoglou et al., ACS Nano 9, 11398 (2015)
Hints Towards 2D Silicon Carbide? 14 Si Sample: reduced graphene oxide Imaging: Nion UltraSTEM 100 @ 60 kV, ca. 30 pA @ 10 -9 mbar Silicon 28.09 70 Silicon 60 50 Tmax (eV) 40 30 20 10 0 50 100 150 200 250 300 U (kV) @ 60 kV ~ 4–6 eV (Si) ~ 10–13 eV (C) 70 Carbon-12 60 Carbon-13 50 Tmax (eV) 40 30 20 10 0 50 100 150 200 250 300 U (kV) Susi, JK, et al. ,Sci. Rep. 7, 4399 (2017)
Susi, JK, et al. ,Sci. Rep. 7, 4399 (2017)
Susi, JK, et al. ,Sci. Rep. 7, 4399 (2017)
Knock-On vs. Ionizatjon, or Both?
Electron irradiatjon of hBN @ 120 kV 5 7 N B Boron Nitrogen 14.00, 15.00 10.01, 11.01 70 Boron-10 60 Boron-11 50 Tmax (eV) 40 30 Jin et al., Phys. Rev. Letu. 102, 195505 (2009) 20 @ 80 kV 10 0 50 100 150 200 250 300 U (kV) 70 Nitrogen-14 60 Nitrogen-15 50 Tmax (eV) 40 30 20 10 0 50 100 150 200 250 300 Meyer et al., Nano Letu. 9, 2683 (2009) U (kV)
(a) 80 kV (b) 120 kV (c) 200 kV Kotakoski et al., Phys. Rev. B 82, 113404 (2010)
Sulfur Vacancies in MoS 2 16 42 S Mo @ 80 kV Sulfur Molybdenum 32.06 95.95 30 Sulfur 25 20 Tmax (eV) 15 10 5 0 50 100 150 200 250 300 U (kV) 30 Molybdenum 25 20 Tmax (eV) 15 10 Komsa, JK et al., Phys. Rev. Letu. 109, 035503 (2012) 5 0 50 100 150 200 250 300 U (kV)
Komsa, JK et al., Phys. Rev. Letu. 109, 035503 (2012) MoS 2 , HRTEM 10 STEM @ 70 kV Geo.mean: 1.1x10 8 e/nm2 8 6 cases 4 2 0 0 1 2 3 4 5 6 7 8 dose (1e9 e/nm2)
From Knock-On to Ionizatjon
Heavier TMDs: MoTe 2 Kuc, Chemical Modelling 11, 1-29 (2014) 16 S 42 Sulfur Mo 32.06 34 Molybdenum Se 95.95 74 Selenium W 30 30 78.971 Molybdenum Tellurium 25 25 52 Tungsten Te 20 20 183.84 @ 60 kV < 2.0 eV @ 60 kV < 1.5 eV Tmax (eV) Tmax (eV) 15 15 Tellurium 10 10 127.60 5 5 0 0 50 100 150 200 250 300 50 100 150 200 250 300 U (kV) U (kV)
Non-knock-on dynamics Elibol, … , JK, Chem. Mater. 30, 1230 (2018)
Elibol, … , JK, Chem. Mater. 30, 1230 (2018)
Intrinsic defects TMD-protectjon through sandwiching: Algara-Siller et al., Appl. Phys. Letu. 103, 203107 (2013) Elibol, … , JK, Chem. Mater. 30, 1230 (2018)
Graphene Edges under the Electron Beam
Typical Results in a HRTEM: Growing Holes Meyer, JK, et al., Phys. Rev. Letu. 108, 196102 (2012) See also: Girit et al., Science 323, 1705 (2009)
What Should We Expect? Knock-on damage at various edges Kotakoski et al., ACS Nano 6, 671 (2012)
Experimental setup in Vienna
… in a STEM at 10 -7 to 10 -6 mbar (O 2 ) STEM imaging at 60 kV unst nstable edges Typical orientatj tjon: Zigza zag Leuthner et al., in preparatjon
Leuthner et al., in preparatjon
How About in UHV? STEM imaging at 60 kV and ca. 2x10 -10 mbar Si-driven dyna namics Most stly: stable armcha hair edges Leuthner et al., in preparatjon
Etching-Induced Cleaning @ 10 -7 mbar (Air) Leuthner et al., in preparatjon
Nion Co. Ondrej Krivanek Tracy Lovejoy Mike Hotz Jannik Meyer Toma S Susi Aalto University, Finland Clemens Mangler Hannu-Pekka Komsa Moha hammad M Mona naza zam Kimmo Mustonen HZDR, Germany Tim Pennycook Arkady Krasheninnikov Bernhard Bayer Viera Skakalova SuperSTEM, UK Franz Eder Quentjn Ramasse Giacomo Argentero Demie Kepaptsoglou Rasim Mirzayev Kenan Elibol University of Ulm, Germany Andreas Mituelberger Ute Kaiser Stefan Hummel Ossi Lehtjnen Greg egor L Leuthn euthner Simon Kurasch Ursula ula L Lud udack cka Muk ukes esh Tripathi Trinity College Dublin, Ireland Chr hristo toph h Hofer er Georg Duesberg Geo eorg Zagler ler Niall McEvoy Heena ena I Ina nani Maria O‘Brien Ale lex C Chi hirita M Miha haila la And ndrea eas P Postl tl AIST, Japan Kazu Suenaga Tobias Görlich Daryoush Nosraty Alamdary Manuel Längle Michael Somma Michael Treacy
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