Detector non-uniformity in scanning transmission electron microscopy

• Published in: Ultramicroscopy Vol. 124; pp. 52 - 60
• Main Authors: Findlay, S.D., LeBeau, J.M.
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 01-01-2013
• Subjects: Detector efficiency; High-angle annular dark field (HAADF); Microscopy, Electron, Scanning Transmission - instrumentation; Microscopy, Electron, Scanning Transmission - methods; Scanning transmission electron microscopy (STEM); Detector efficiency; Scanning transmission electron microscopy (STEM); High-angle annular dark field (HAADF)
• ISSN: 0304-3991; 1879-2723
• DOI: 10.1016/j.ultramic.2012.09.001

A non-uniform response across scanning transmission electron microscope annular detectors has been found experimentally, but is seldom incorporated into simulations. Through case study simulations, we establish the nature and scale of the discrepancies which may arise from failing to account for detector non-uniformity. If standard detectors are used at long camera lengths such that the detector is within or near to the bright field region, we find errors in contrast of the order of 10%, sufficiently small for qualitative work but non-trivial as experiments become more quantitative. In cases where the detector has been characterized in advance, we discuss the detector response normalization and how it may be incorporated in simulations.
► We explore the influence of a non-uniform detection response on the quantification of STEM images across the range of detection geometries. ► We show that significant errors for quantification are possible, particularly for annular bright field imaging. ► The influence of an off-centered defector is investigated.