Metal assisted chemical etching with interconnected catalyst structures has been used to create a wide array of organized nanostructures. However, when patterned catalysts are not interconnected, but are isolated instead, vertical etching to form controlled features is difficult. A systematic study of the mechanism and catalyst stability of metal assisted chemical etching (MACE) of Si in HF and H(2)O(2) using Au catalysts has been carried out. The effects of the etchants on the stability of Au catalysts were examined in detail. The role of excess electronic holes as a result of MACE was investigated via pit formation as a function of catalyst proximity and H(2)O(2) concentration. We show that a suppression of excess holes can be achieved by either adding NaCl to or increasing the HF concentration of the etching solution. We demonstrate that an electric field can direct most of the excess holes to the back of the Si wafer and thus reduce pit formation at the surface of Si between the Au catalysts. The effect of hydrogen bubbles, generated as a consequence of MACE, on the stability of Au catalysts has also been investigated. We define a regime of etch chemistry and catalyst spacing for which catalyst stability and vertical etching can be achieved.
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http://dx.doi.org/10.1039/c2nr32350h | DOI Listing |
Nanophotonics
April 2024
Department of Bio-Functions and Systems Science, Tokyo University of Agriculture and Technology, Koganei, Tokyo 184-8588 Japan.
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School of Physical Science and Technology, Xinjiang University, Urumchi 830017, China.
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Laboratory of Solar Fuel, Faculty of Materials Science and Chemistry, China University of Geosciences, 68 Jincheng Street, Wuhan 430078, China. Electronic address:
Graphene-based metal selenides, are increasingly recognized for their potential in sodium-ion battery applications due to their superior electrochemical properties. The unique structure of graphene facilitates rapid in-plane transport of sodium ions, but the interlayer diffusion remains a significant challenge. The NiSe@CoSe heterojunctions, strategically grown adjacent to the graphene pores, offer a novel solution by creating in-plane holes that serve as direct channels for vertical ion transport, thereby enhancing cross-layer sodium ion permeation.
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