In situ STEM analysis of electron beam induced chemical etching of an ultra-thin amorphous carbon foil by oxygen during high resolution scanning

Autor(en)

Stefan Manuel Noisternig, Christian Rentenberger, H. Peter Karnthaler

Abstrakt

Support foils for (scanning) transmission electron microscopy ((S)TEM) samples are commonly amorphous carbon foils. State of the art (S)TEM high resolution imaging methods use ultra-thin carbon foils of only a few nm thickness, especially for imaging beam sensitive materials with low acceleration voltages and electron fluxes. In this study we analyze in situ the effect of chemical etching on a 2 nm amorphous carbon foil due to residual oxygen and by leaking in oxygen into the microscope column. We vary the vacuum level on a Nion UltraStem 100 between ultra high vacuum and that typical in TEM. This enables us to carry out a systematic investigation of chemical etching as function of both, oxygen pressure and electron flux. In addition the results of chemical etching are compared with those of sputtering from knock-on damage leading to the conclusion that chemical etching is the important cause for carbon removal from an amorphous foil at low oxygen pressures and low electron fluxes. We observe that the electron flux dependency using high resolution scanning conditions differs from the case of a resting electron beam. To interpret the results of chemical etching a scanning etching model is proposed that takes care of the specific conditions of STEM.

Organisation(en)

Physik Nanostrukturierter Materialien

Journal

Ultramicroscopy

Band

235

Anzahl der Seiten

10

ISSN

0304-3991

DOI

https://doi.org/10.1016/j.ultramic.2022.113483

Publikationsdatum

05-2022

Peer-reviewed

Ja

ÖFOS 2012

103042 Elektronenmikroskopie, 103018 Materialphysik

Schlagwörter

ASJC Scopus Sachgebiete

Electronic, Optical and Magnetic Materials, Atomic and Molecular Physics, and Optics, Instrumentation

Link zum Portal

https://ucrisportal.univie.ac.at/de/publications/c4d6432c-e412-49d5-9ba4-dd0ba1530154