Graphene‐supported microwell liquid cell for in situ studies in TEM and SEM

Conference contribution
(Conference Contribution)


Publication Details

Author(s): Hutzler A, Branscheid R, Jank M, Frey L, Spiecker E
Publisher: Wiley Online Libary
Publication year: 2016
Conference Proceedings Title: European Microscopy Congress 2016 Volume 1: Instrumentation and Methods
Pages range: 209 - 210
Language: English


Abstract



Liquid cell transmission electron microscopy (LCTEM) is used for in situ
investigations of dynamic nanoparticulate processes in aqueous and
nonaqueous solutions. In contrast to complementary techniques like
conventional (S)TEM, cryo‐TEM or SAXS, LCTEM ensures real‐time
high‐resolution imaging and is used in various research fields like
biology, electrochemistry and materials science [1]. For our approach we
make use of a modified microwell liquid cell layout combining the
benefits of the microwell liquid cell design used by Dukes et al. [2] and the graphene liquid cell shown by Yuk et al. [3] for in situ
(S)TEM and SEM experiments. In this approach, the liquid specimen is
confined between amorphous silicon nitride microwells and multilayer
graphene (cf. fig. 1). This enables improved imaging conditions compared
to other cell designs because the cell profits from the advantages of
(i) a robust encasement combined with an ultrathin and electrically
conducting low‐Z material and (ii) a constant liquid film‐thickness
defined by the nitride wells. Furthermore, in this design window bulging
is largely suppressed due to small microwell diameters on the order of 5
µm. The liquid cells are processed under clean room conditions via
conventional semiconductor technology as well as bulk micromachining. In
a first step a silicon nitride layer is deposited onto an oxidized thin
silicon wafer via LPCVD followed by structuring the front and back‐side
by photolithography and reactive ion etching. For the simplified device
layout no mask alignment is necessary which minimizes the failure
probability and improves the yield of the fabrication process.
Furthermore, the number of process steps could be considerably reduced
compared to the fabrication process of conventional static liquid cells.
Bulk micromachining of the silicon wafer is done by an anisotropic
potassium hydroxide wet‐etching process. The filling and vacuum tight
sealing of the cell is conducted in one step by transferring the
graphene directly onto a droplet of the specimen solution. When the
liquid dries the graphene adheres to the silicon nitride and encloses
small amounts of the fluid within the microwells. The compatibility to
conventional specimen holders makes the liquid cells feasible for the
use with various kinds of TEMs and SEMs.



As first application and test of this optimized liquid cell
design electron beam induced growth and degradation phenomena of
Au‐nanoparticles in HAuCl4‐solution have been studied. Figure 2 shows snapshots of an in situ
TEM investigation monitoring the dissolution of a Au‐nanoplatelet at a
liquid‐gas interface and the subsequent growth of smaller particles
above (or below) the gas bubble. This redistribution of material is
facilitated by the high mobility of gold‐atoms in solution as well as by
reactive species generated by electron beam irradiation of the aqueous
solution. The experiment was carried out in TEM bright‐field mode using a
Philips CM‐30 (S)TEM operated at 300 kV. In order to demonstrate that
the cell can be equally used inside an SEM figure 3 shows snapshots of
an in situ study of electron beam induced dendrite‐growth of Au‐nanostructures in a 1 mM HAuCl4‐solution. Here, imaging was carried out in STEM mode using a FEI Helios Nanolab 660 operated at 29 keV primary electron energy.




FAU Authors / FAU Editors

Branscheid, Robert
Lehrstuhl für Werkstoffwissenschaften (Mikro- und Nanostrukturforschung)
Frey, Lothar Prof. Dr.
Lehrstuhl für Elektronische Bauelemente
Hutzler, Andreas Dr.-Ing.
Lehrstuhl für Elektronische Bauelemente
Spiecker, Erdmann Prof. Dr.
Lehrstuhl für Werkstoffwissenschaften (Mikro- und Nanostrukturforschung)


Additional Organisation
Interdisziplinäres Zentrum, Center for Nanoanalysis and Electron Microscopy (CENEM)
Graduiertenkolleg 1896/2 In situ Mikroskopie mit Elektronen, Röntgenstrahlen und Rastersonden
Lehrstuhl für Werkstoffwissenschaften (Mikro- und Nanostrukturforschung)


External institutions with authors

Fraunhofer-Institut für Integrierte Systeme und Bauelementetechnologie (IISB)


How to cite

APA:
Hutzler, A., Branscheid, R., Jank, M., Frey, L., & Spiecker, E. (2016). Graphene‐supported microwell liquid cell for in situ studies in TEM and SEM. In European Microscopy Congress 2016 Volume 1: Instrumentation and Methods (pp. 209 - 210). Lyon, FR: Wiley Online Libary.

MLA:
Hutzler, Andreas, et al. "Graphene‐supported microwell liquid cell for in situ studies in TEM and SEM." Proceedings of the European Microscopy Congress 2016, Lyon Wiley Online Libary, 2016. 209 - 210.

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Last updated on 2019-29-05 at 09:17