A well-aligned silicon nanograss has been fabricated on a silicon wafer through hydrogen plasma etching alone, i.e., without the use of a mask or a catalyst. A mechanism is proposed for this process according to the results of electron microscopy analyses and experiments on the silicon oxide-patterned silicon wafer. The results obtained when modulating the bias conditions lend support to the proposed mechanism. This method can be extended to the fabrication of quantum dots when thin films are used in the etching process. (c) 2005 The Electrochemical Society.