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A regenerative electroless etching process produces nanostructured semiconductors in which an oxidant (Ox 1 ) is used as a catalytic agent to facilitate reaction between a semiconductor and a second oxidant (Ox2) that would be unreactive (or slowly reactive compared to Ox 1 ) in the primary reaction. Ox2 is used to regenerate Ox1 , which can initiate etching by injecting holes into the semiconductor valence band. The extent of reaction is controlled by the amount of Ox2 added; the reaction rate, by the injection rate of Ox2 . This general strategy is demonstrated specifically to produce highly luminescent nanocrystalline porous, amorphous pillared, and hierarchical porous silicon from the reaction of V2O5 in HF(aq) as Ox1 and H2Oiaq) as Ox2 with a silicon-comprising substrate. The process can be performed on silicon-comprising substrates of arbitrary size and shape including powders, reclaimed shards, wafers, pillared silicon, porous silicon, and silicon nanowires. Luminescence is tuned by adjusting etching conditions.


Patent No.: US 10,590,562 B2