In Situ Liquid TEM of Ge Nanowire Synthesis with Liquid Metal Nanodroplets

As part of a collaboration with Hummingbird Scientific, researchers at the University of Michigan used Hummingbird Scientific’s In-situ TEM liquid cell holder to investigate germanium nanowire synthesis from solution.  They studied electron-radiated gallium and indium liquid metal droplets as germanium nanowires grew from a solution of water and GeO2 in-situ in the TEM.

 

These experiments lead to the following conclusions. The conditions necessary for initiating nanowire growth was governed by solvated electrons generated from secondary electrons scattered by the liquid metal nanodroplets. Furthermore, the surface condition of the liquid metal nanodroplets was quite influential on whether nanowire growth occurred and surface diffusion of Ge adatoms contributed to the rate of crystallization. Also, the Ge nanowire growth rates were limited by the feed rate of Ge to the crystal growth front rather than the rate of crystallization at the liquid metal/solid Ge interface. Finally, the Ge nanowire growths occurred far from thermodynamic equilibrium, with supersaturation values of 104 prior to nucleation. These collective points provide insight on how to further control and improve Ge nanowire morphology and crystallographic quality by the ec-LLS method. They published their findings in ACS Nano.

 

Frame grabs from an in-situ transmission electron microscopy video of parallel Ge nanowire growth events at In nanodroplets immersed in aqueous solution with a formal GeO2 concentration of 0.05 M (a). Frame grabs from an in-situ transmission electron microscopy video of a single Ge nanowire growth event in an aqueous solution with a formal GeO2 concentration of 0.05 M (b).
Copyright © 2020 American Chemical Society

 

Reference: Quintin Cheek, Eli Fahrenkrug, Sofiya Hlynchuk, Daan Hein Alsem, Norman J.  Salmon and Stephen Maldonado, “In Situ Transmission Electron Microscopy Measurements of Ge Nanowire Synthesis with Liquid Metal Nanodroplets in Water”, ACS Nano 2020, 14, 3, 2869-2879,  https://pubs.acs.org/doi/10.1021/acsnano.9b06468

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