PM-03Development of Fast Pixelated STEM Detector and Its Applications

A pixelated STEM detector can record 4D dataset, composed of a series of diffraction patterns (2D) for probe positions (2D). It enables us to synthesize various types of STEM images such as DPC image using a user-defined integration area on the detector plane. We have developed a pixelated STEM detector (JEOL, 4DCanvas) using a fast direct electron CCD image sensor (PNDetector, pnCCD) whose maximum readout speed is 4,000 fps. The detector is integrated into JEM-ARM200F microscope with our operational software. One of the applications using 4D dataset is a post processing technique called ptychography [1]. Figures show a comparison of simultaneously recorded graphene images (a) ADF STEM image by a conventional STEM detector and (b) a phase image after ptychographical reconstruction from 4D dataset by the 4DCanvas. Intensity profiles along the dotted lines show that the phase image apparently gives higher SNR and image contrast. 1. PD Nellist et al., Nature 374 (1995) 630–632.