4D STEM: High efficiency phase contrast imaging using a fast pixelated detector

Electron Microscopy and Analysis Group Conference 2015

Yang, H.^1 ; Jones, L.^1 ; Ryll, H.^2 ; Simson, M.^3 ; Soltau, H.^3 ; Kondo, Y.^4 ; Sagawa, R.^4 ; Banba, H.^4 ; MacLaren, I.^5 ; Nellist, P.D.^1

Department of Materials, University of Oxford, Parks Rd, Oxford, United Kingdom^1

PNSensor GmbH, Otto-Hahn-Ring 6, München

81739, Germany^2

PNDetector GmbH, Sckellstraße 3, München

81667, Germany^3

JEOL Ltd., 3-1-2 Musashino, Akishima Tokyo

196-8558, Japan^4

University of Glasgow, Glasgow

G12 8QQ, United Kingdom^5

关键词: Frames per seconds;    High-efficiency;    Phase reconstruction;    Phase-contrast imaging;    Pixelated detectors;    Transmission function;    Weak phase object;    Z-contrast imaging;   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/644/1/012032/pdf
DOI  :  10.1088/1742-6596/644/1/012032

来源: IOP

【 摘 要 】

Phase contrast imaging is widely used for imaging beam sensitive and weak phase objects in electron microscopy. In this work we demonstrate the achievement of high efficient phase contrast imaging in STEM using the pnCCD, a fast direct electron pixelated detector, which records the diffraction patterns at every probe position with a speed of 1000 to 4000 frames per second, forming a 4D STEM dataset simultaneously with the incoherent Z-contrast imaging. Ptychographic phase reconstruction has been applied and the obtained complex transmission function reveals the phase of the specimen. The results using GaN and Ti, Nd- doped BiFeO3show that this imaging mode is especially powerful for imaging light elements in the presence of much heavier elements.