Berlin 2012 – wissenschaftliches Programm
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MM: Fachverband Metall- und Materialphysik
MM 17: Poster Session
MM 17.12: Poster
Montag, 26. März 2012, 17:00–19:00, Poster B
Direct Single Electron Imaging with a pnCCD for TEM — •Henning Ryll1, Robert Hartmann1, Robert Andritschke2, Sebastian Ihle1, Heike Soltau1, and Lothar Strüder2 — 1PNSensor GmbH, München — 2Max-Planck-Institut für extraterrestrische Physik, Halbleiterlabor, München
Promising better resolution and sensitivity, work on a spatially resolving direct electron detector, based on a pnCCD is presented.
A pnCCD is a back-illuminated silicon detector, which is sidewards depleted. By applying appropriate voltages to both sides, the whole 450 um thick bulk, high-purity n-type silicon is depleted.
Up to 1000 full frames per second are achieved, enabling the imaging of single electrons in ultra-low dose modes and the observation of changes in samples. Each electron creates a signal easily distinguished from the noise. The final image is obtained by successive addition of individual frames and their intensities. Additionally image processing at the single incident electron level and its signal can be performed.
In order to determine the characteristics of the pnCCD, one type with a pixelsize of 51x51um^2 was tested on a Phillips CM12 120 keV TEM. A slanted knife edge was placed in front of the detector to determine the MTF. Operating at 120 keV and a low dose, applying signal processing allowed for a software subpixel resolution, improving the MTF to >40% @ Nyquist.
Simulations complementing the experimental data will be presented, as well as the expected pixel patterns and their analysis for different energies.