QUANTAX EBSD with OPTIMUS TKD Transmission Kikuchi Diffraction Under Optimum Conditions

Transcription

1 QUANTAX EBSD with OPTIMUS TKD Transmission Kikuchi Diffraction Under Optimum Conditions Bruker Nano GmbH, Berlin, Germany Webinar, August 26 th, 2015 Innovation with Integrity

2 Speaker Dr. Daniel Goran Product Manager EBSD Bruker Nano GmbH, Berlin, Germany 2

3 Acknowledgments J.-J. Fundenberger and E. Bouzy from Lorraine University in Metz, France Joe Michael from Sandia National Laboratories in Albuquerque, NM, USA 3

4 Overview Introduction OPTIMUS TKD o Main features o Advantages spatial resolution & indexing quality o Application examples & more Summary 4

5 Transmission Kikuchi Diffraction in SEM Introduction Why? SEM based technique using EBSD HW & SW It requires electron transparent samples Lateral spatial resolution up to 10x better as compared to EBSD* Significant limitations/issues due to HW design (not intended for this sampledetector geometry) 1. Signal loss 2. Pattern distortions * R. Keller and R. Geiss, Journal of Microscopy, Vol. 245, Pt , pp * P. W. Trimby, Ultramicroscopy, 120, 16 24, * N. Brodusch, H. Demers and R. Gauvin, Journal of Microscopy, Vol. 250, Pt , pp

6 Transmission Kikuchi Diffraction in SEM Introduction Phosphor screen Incident beam PPPP DDDD Pole piece Sample holder Why? - Signal yield decreases exponentially with scattering angle θ: Slower acquisition speeds o lower efficiency EBSD Detector θ Scattered electron cloud o measurements more prone to beam instability Larger probe currents o resolution loss Transmitted beam o sample damage (carbon contamination) Shorter DD values limited by o space around the sample o reduction of active area 6

7 Transmission Kikuchi Diffraction in SEM Introduction Why? pattern distortions: Phosphor screen Incident beam PPPP DDDD Pole piece Sample holder PC is outside the screen very strong gnomonic projection induced distortions negative influence on band detection and indexing quality θ EBSD Detector Scattered electron cloud Transmitted beam 7

8 Optimum geometry for TKD analysis Solving both problems with: Standard EBSD detector head OPTIMUS TKD detector head 8

9 Optimum geometry for TKD analysis OPTIMUS TKD main features: Horizontal phosphor screen optimum geometry for capturing transmitted scattered electron signal ARGUS FSE imaging system integrated Easy to use/switch between EBSD and TKD modes Built-in collision sensor Compatible with all existing e - Flash detectors 9

10 Optimum geometry for TKD analysis Main features: Horizontal phosphor screen Mirror inclined at 45 Advantages: Gain in signal at least 12x stronger Vertical SiC sample EHT=20kV OPTIMUS Probe current: 3.5nA 0.8nA Exposure time: 250ms 80ms 10

11 Better spatial resolution Better signal - improved spatial resolution: Sample: Gibeon Meteorite (prepared by FIB) Contains small fcc grains in bcc matrix Acquisition speed: ~140fps 1.7nA 4nA Acquired with the vertical screen Acquired with OPTIMUS TKD 11

12 Better spatial resolution Improved spatial resolution: FCC annealing twins 6nm wide (two pixels) Much better indexing quality 1.7nA 4nA Acquired with the vertical screen Acquired with OPTIMUS TKD 12

13 Better indexing quality Improved indexing quality: ~9x less zero solutions (even after plasma cleaning) Raw data - no data cleaning applied Zero solutions: 20.2% Zero solutions: 2.4% 13

14 Better spatial resolution Improved spatial resolution One pixel boundaries => 4nm physical spatial resolution Effective spatial resolution is better than 4nm Sample: Au (prepared by FIB) EHT: 28kV Aperture: 30μm Probe current: ~0.6nA Zero solutions: 4.9% 14

15 Better indexing quality OPTIMUS TKD - advantages: Reduced gnomonic projection distortions Vertical OPTIMUS 15

16 Better indexing quality Reduced gnomonic projection distortions: More accurate band detection Better indexing Less zero solutions Exposure time: 10ms No frame averaging Pattern resolution: 200x150pixels (8x8 binning) 16

17 Integrated ARGUS imaging system OPTIMUS TKD - main features: Built-in ARGUS imaging system 3x high sensitivity Si diodes Dark field imaging (3x diodes) SiC - 3x diodes Special thanks to Isabella van Rooyen from Idaho National Laboratory, USA for providing the sample 17

18 Integrated ARGUS imaging system 18

19 Integrated ARGUS imaging system 19

20 Integrated ARGUS imaging system ARGUS imaging system Qualitative information: ECAE deformed pure Al sample Individual dislocations Dislocation walls 20

21 Integrated ARGUS imaging system ARB deformed Al - middle diode OPTIMUS TKD - main features: Built-in ARGUS imaging system: 3x high sensitivity Si diodes Bright field imaging (middle diode) Dark field imaging (left & right diodes) ARB deformed Al left&right diodes Special thanks to Patrick Woo from Hitachi High-Technologies, Canada for providing the sample 21

22 Transmission Kikuchi Diffraction in SEM Advantages Sharp boundaries have their planes parallel or close to parallel with transmitted beam FIB prepared SiC - pixel size 2nm Inclined boundary planes produce a mixture of colors of the two neighboring grains Detected diffraction signal originates in the entire volume between entry and exit surfaces with weight decreasing with distance from the exit surface Special thanks to Isabella van Rooyen from Idaho National Laboratory, USA for providing the sample 22

23 Transmission Kikuchi Diffraction in SEM Advantages Using thinner samples FIB technique is most appropriate: Control the in-depth spatial resolution o less overlapping around inclined boundary planes o avoid analyzing samples made of more than two layers of grains Up-side: Thinner samples reduced incident beam scattering further improve the lateral spatial resolution Down-side: Thinner samples smaller interacting volume reduced Kikuchi diffraction signal 23

24 Transmission Kikuchi Diffraction in SEM Advantages OPTIMUS TKD advantages: Use lower kv decrease mean free path increase Kikuchi signal yield Optimize electron beam parameters for a given sample chemistry and thickness Sample: SiC / EHT: 15kV Sample: SiC / EHT: 30kV 24

25 Easy to use Other features: Built-in collision sensor (10mm/s retraction speed) User replaceable (plug & play) User replaceable phosphor screen Compatible with all existing e - Flash detectors EBSD TKD Switch between EBSD and TKD modes in less than 20 minutes 25

26 QUANTAX EBSD Complete TKD solution from Bruker OPTIMUS TKD detector head Professional TKD toolkit (now containing 8 items) Software (ESPRIT 2.0.4) adapted to work with OPTIMUS 26

27 QUANTAX EBSD OPTIMUS TKD Summary One detector two optimum solutions: OPTIMUS TKD transforms your SEM into a low kv TEM o Imaging STEM o Electron diffraction orientation/phase mapping Qualitative and quantitative characterization of materials with no compromises from macro to nano scale EBSD TKD 27

28 Q&A Any Questions? Please type in the questions you might have in the Q&A box and press Submit. 28

29 Copyright 2015 Bruker Corporation. All rights reserved. Innovation with Integrity