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Hole-Free Phase Plate Energy Filtering Imaging of Graphene: Toward Quantitative Hole-Free Phase Plate Imaging in a TEM

Hole free phase plate (HFPP) imaging has been developed to increase TEM phase contrast for qualitative imaging purposes [1] in the sense that the image intensity is not related to sample properties in a simple manner. Here we report simultaneous utilization of HFPP and energy filtered TEM (EFTEM) thickness mapping as a first step toward quantitative HFPP imaging, using a contaminated graphene film as test specimen. The data were collected in a JEOL JEM 2200 FS TEM operated at 200 kV with a Schottky electron source and an in-column omega filter. The HFPP is placed at the in-gap objective aperture plane, enabling us to utilize microscope magnification between 1500x and 1Mx. The carbon phase plate was heated during operation to about 250 °C and data were collected after the HFPP was allowed to settle for about 100 s.