University of Maryland Electron Microscopy Workshops: Recent Advancements in Electron and Ion Microscopy
Workshop Day 1: May 17, 2016
Kay Boardrooms, Jeong H. Kim Engineering Building
Application of High Speed Cameras for 4D Data Collection in STEM
Anahita Pakzad, Gatan, Inc.
(3:10 p.m. – 3:30 p.m.)
STEM diffraction imaging is an accurate analysis technique to acquire information on material structure, strain, and texture. In this technique either a parallel or a convergent electron beam with a probe size as small as 0.2 nm is passed through the specimen to generate diffraction patterns. These patterns can be used to characterize individual nano particles, defects and interfaces and allow accurate measurements of strain and crystal orientation. 4D-STEM diffraction data is collected by scanning the electron probe on the specimen and collecting a diffraction pattern at each pixel of the scan. One of the main drawbacks with this technique has been the limitation of the data collection speed. Conventional CCD cameras are limited to about 30 frames per second (fps), which limits the number of diffraction patterns that can be collected in a reasonable amount of time. This is even more disadvantageous in cases where specimens are beam sensitive and/or drift. In such cases by the time data collection is complete, the sample has experienced radiation damaged or moved out of the field of view. In this talk, 4D STEM datasets collected with both high speed CMOS and conventional CCD cameras will be compared, to show how newly developed CMOS systems with superior DQE and speed can benefit such experiments.