On 2 n 2D M Mate terials & s & Thei heir Defects ects - - PowerPoint PPT Presentation

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) Nan et al., ACS Nano 8, 5738 (2014)

MoS2

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)

Krivanek et al., Ultramicroscopy 108, 179 (2008)

Nion UltraSTEM 100 @ Vienna

Pennycook et al., MRS Bulletjn 31, 36 (2006)

Nion UltraSTEM 100 @ Vienna

JK et al., Nat. Commun. 5, 4991 (2014) Krivanek et al., Nature 464, 571 (2010) Ramasse et al, Nano Letu. 13, 4989 (2013) Susi, JK, et al. ,2D Mater. 4, 021013 (2017)

knock-on excitatjons & ionizatjon chemical efgects

O OH O H H

Electron Beam Efgects in the (S)TEM

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: 106 barn cross sectjon: 106 barn tjme scale: 10-15 s tjme scale: 10-15 s tjme scale: 10-13 s Phonons ns (elastj stjc collision) Core hole cross sectjon: 106 barn cross sectjon: 104 barn 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)

Beam Current: 30 pA

• ca. 1 e- / nm2 / 10-9 s

Knock-On Process

Conservatjon of energy Conservatjon of momentum Maximum energy transfer occurs for the back scatuering electron and yields

Banhart, Rep. Prog. Phys. 62, 1181 (1999)

Electron energy: eU Initjal velocity of the nucleus

• r

for v = 0

10 20 30 40 50 60 70 50 100 150 200 250 300 Tmax (eV) U (kV) Carbon-12 Carbon-13

6

C

Carbon 12, 13.01

m: 0.51 MeV/c2 M: Z x 931.49 MeV/c2 Velocity here from kinetjc theory: Betuer, phonon DOS:

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

Coulomb Interactjon: Nucleus: Q2 = Z Electron: Q1 = 1 Rutherford scatuering: (valid for charges at low energies) Extended for spin and relatjvistjc electrons by Motu & approximated by McKinley and Feshbach:

See: Zobelli et al., Phys. Rev. B 75, 245402 (2007) McKinley and H. Feshbach, Phys. Rev. 74, 1759 (1948)

Using

• ne gets

Energy of nucleus afuer scatuering Electron scatuering angle Assuming isotropic displacement threshold Ed and integratjng over T > Ed leads to:

Meyer, JK, et al., Phys. Rev. Letu. 108, 196102 (2012)

Theory vs. experiment

0.00 0.05 0.10 0.15 0.20 0.25 75 80 85 90 95 100 105 110 115 Cross sectjon (barn) Electron energy (keV) 5 10 15 20 80 100 120 140 160 180 200 Cross sectjon (barn) Electron energy (keV) 22 eV 22 eV 18 eV Experiment Experiment 18 eV

Susi, …, JK, Nat. Commun. 7, 13040 (2016)

Velocity distributjon of nuclei Extended model:

Sub-threshold Knock-On Efgects

Dynamical process due to an impact on one atom

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)

Stone-Wales „Flower defect“ Divacancy

From Single- to Multjvacancies

Kotakoski et al., Phys. Rev. Letu. 106, 105505 (2011) & Kotakoski et al., Phys. Rev. B 89, 201406 (2014)

@ 100 kV

… and to Amorphous 2D Carbon

Kotakoski et al., Phys. Rev. Letu. 106, 105505 (2011) & Eder, JK et al., Sci. Rep. 4, 4060 (2014)

@ 100 kV

Impurity Atom Dynamics

Observed dynamics

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) Susi, …, JK, 2D Mater. 4, 042004 (2017)

Hints Towards 2D Silicon Carbide?

Sample: reduced graphene oxide Imaging: Nion UltraSTEM 100 @ 60 kV, ca. 30 pA @ 10-9 mbar

Susi, JK, et al. ,Sci. Rep. 7, 4399 (2017)

14

Si

Silicon 28.09

10 20 30 40 50 60 70 50 100 150 200 250 300 Tmax (eV) U (kV) Silicon

@ 60 kV ~ 4–6 eV (Si) ~ 10–13 eV (C)

10 20 30 40 50 60 70 50 100 150 200 250 300 Tmax (eV) U (kV) Carbon-12 Carbon-13

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

5

B

Boron 10.01, 11.01 7

N

Nitrogen 14.00, 15.00

10 20 30 40 50 60 70 50 100 150 200 250 300 Tmax (eV) U (kV) Boron-10 Boron-11 10 20 30 40 50 60 70 50 100 150 200 250 300 Tmax (eV) U (kV) Nitrogen-14 Nitrogen-15

@ 120 kV

Jin et al., Phys. Rev. Letu. 102, 195505 (2009) Meyer et al., Nano Letu. 9, 2683 (2009)

@ 80 kV

Kotakoski et al., Phys. Rev. B 82, 113404 (2010)

(a) 80 kV (b) 120 kV (c) 200 kV

Sulfur Vacancies in MoS2

16

S

Sulfur 32.06

5 10 15 20 25 30 50 100 150 200 250 300 Tmax (eV) U (kV) Sulfur

42

Mo

Molybdenum 95.95

5 10 15 20 25 30 50 100 150 200 250 300 Tmax (eV) U (kV) Molybdenum

@ 80 kV

Komsa, JK et al., Phys. Rev. Letu. 109, 035503 (2012)

Komsa, JK et al., Phys. Rev. Letu. 109, 035503 (2012)

MoS2, HRTEM STEM @ 70 kV

Geo.mean: 1.1x108 e/nm2

2 4 6 8 10 1 2 3 4 5 6 7 8 cases dose (1e9 e/nm2)

From Knock-On to Ionizatjon

Heavier TMDs: MoTe2

Kuc, Chemical Modelling 11, 1-29 (2014)

42

Mo

Molybdenum 95.95 74

W

Tungsten 183.84 16

S

Sulfur 32.06 34

Se

Selenium 78.971 52

Te

Tellurium 127.60

5 10 15 20 25 30 50 100 150 200 250 300 Tmax (eV) U (kV) Molybdenum 5 10 15 20 25 30 50 100 150 200 250 300 Tmax (eV) U (kV) Tellurium

@ 60 kV < 1.5 eV @ 60 kV < 2.0 eV

Elibol, … , JK, Chem. Mater. 30, 1230 (2018)

Non-knock-on dynamics

Elibol, … , JK, Chem. Mater. 30, 1230 (2018)

Intrinsic defects

Elibol, … , JK, Chem. Mater. 30, 1230 (2018) TMD-protectjon through sandwiching: Algara-Siller et al., Appl. Phys. Letu. 103, 203107 (2013)

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?

Kotakoski et al., ACS Nano 6, 671 (2012)

Knock-on damage at various edges

Experimental setup in Vienna

… in a STEM at 10-7 to 10-6 mbar (O2)

Leuthner et al., in preparatjon

STEM imaging at 60 kV unst nstable edges Typical orientatj tjon: Zigza zag

Leuthner et al., in preparatjon

How About in UHV?

Leuthner et al., in preparatjon

STEM imaging at 60 kV and ca. 2x10-10 mbar Si-driven dyna namics Most stly: stable armcha hair edges

Etching-Induced Cleaning @ 10-7 mbar (Air)

Leuthner et al., in preparatjon

Jannik Meyer Toma S Susi Clemens Mangler Moha hammad M Mona naza zam Kimmo Mustonen Tim Pennycook Bernhard Bayer Viera Skakalova Franz Eder Giacomo Argentero Rasim Mirzayev Kenan Elibol Andreas Mituelberger Stefan Hummel Greg egor L Leuthn euthner Ursula ula L Lud udack cka Muk ukes esh Tripathi Chr hristo toph h Hofer er Geo eorg Zagler ler Heena ena I Ina nani Ale lex C Chi hirita M Miha haila la And ndrea eas P Postl tl Tobias Görlich Daryoush Nosraty Alamdary Manuel Längle Michael Somma Michael Treacy University of Ulm, Germany Ute Kaiser Ossi Lehtjnen Simon Kurasch SuperSTEM, UK Quentjn Ramasse Demie Kepaptsoglou Trinity College Dublin, Ireland Georg Duesberg Niall McEvoy Maria O‘Brien Nion Co. Ondrej Krivanek Tracy Lovejoy Mike Hotz Aalto University, Finland Hannu-Pekka Komsa HZDR, Germany Arkady Krasheninnikov AIST, Japan Kazu Suenaga