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Contamination of TEM Holders Quantified and Mitigated With the Open-Hardware, High-Vacuum Bakeout System

Published online by Cambridge University Press:  14 July 2020

Yin Min Goh Open the ORCID record for Yin Min Goh [Opens in a new window] ,
Jonathan Schwartz Open the ORCID record for Jonathan Schwartz [Opens in a new window] ,
Emily Rennich ,
Tao Ma ,
Bobby Kerns  and
Robert Hovden
Yin Min Goh
Affiliation:
Department of Physics, University of Michigan, Ann Arbor, MI48109, USA
Jonathan Schwartz
Affiliation:
Department of Materials Science and Engineering, University of Michigan, Ann Arbor, MI 48109, USA
Emily Rennich
Affiliation:
Department of Mechanical Engineering, University of Michigan, Ann Arbor, MI48109, USA
Tao Ma
Affiliation:
Michigan Center for Materials Characterization, University of Michigan, Ann Arbor, MI48109, USA
Bobby Kerns
Affiliation:
Applied Physics Program, University of Michigan, Ann Arbor, MI48109, USA
Robert Hovden*
Affiliation:
Department of Materials Science and Engineering, University of Michigan, Ann Arbor, MI 48109, USA Applied Physics Program, University of Michigan, Ann Arbor, MI48109, USA
*
*Author for correspondence: Robert Hovden, E-mail: hovden@umich.edu
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Abstract

Hydrocarbon contamination plagues high-resolution and analytical electron microscopy by depositing carbonaceous layers onto surfaces during electron irradiation, which can render carefully prepared specimens useless. Increased specimen thickness degrades resolution with beam broadening alongside loss of contrast. The large inelastic cross-section of carbon hampers accurate atomic species detection. Oxygen and water molecules pose problems of lattice damage by chemically etching the specimen during imaging. These constraints on high-resolution and spectroscopic imaging demand clean, high-vacuum microscopes with dry pumps. Here, we present an open-hardware design of a high-vacuum manifold for transmission electron microscopy (TEM) holders to mitigate hydrocarbon and residual species exposure. We quantitatively show that TEM holders are inherently dirty and introduce a range of unwanted chemical species. Overnight storage in our manifold reduces contaminants by one to two orders of magnitude and promotes two to four times faster vacuum recovery. A built-in bakeout system further reduces contaminants partial pressure to below 10−10 hPa (Torr) (approximately four orders of magnitude down from ambient storage) and alleviates monolayer adsorption during a typical TEM experiment. We determine that bakeout of TEM holder with specimen held therein is the optimal cleaning method. Our high-vacuum manifold design is published with open-source blueprints, parts, and cost list.

Keywords

contaminationopen hardwareTEMtransmission electron microscopy
Type
Software and Instrumentation
Information
Microscopy and Microanalysis , Volume 26 , Issue 5 , October 2020 , pp. 906 - 912
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Copyright
Copyright © Microscopy Society of America 2020

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