Catalyst-assisted chemical etching is an emerging technology in the formation of semiconductor surfaces with various structures and functions. Because this etching utilizes chemical reactions, it does not leave mechanical damages on a processed surface. In addition, by controlling solution conditions, a semiconductor surface in contact with a catalyst can be etched selectively, which has a potential to realize surface structures with a high-aspect ratio. In general, precious metals such as Pt and Ag are used as catalysts in this etching mode. In contrast, we propose to use a carbon-based catalyst such as reduced graphene oxide which can be well dispersed in liquid. In this report, we present our recent results on nanocarbon-assisted chemical etching of a Ge surface in water with dissolved oxygen molecules. After showing fundamental properties, we demonstrate to form a trench pattern on Ge by a patterned catalytic film composed of nanocarbons.
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