A Ag2CrO4/HF/H2O system has been developed that is particularly suitable for use in fabricating well-aligned Si nanowire (SiNW) arrays on Si substrates. This system provides large-area brushlike nanowire arrays on the etched surfaces. The nanowire length can be controlled by changing the etchant component proportions and etching conditions, such as the solution temperature and the etching time. The longest nanowire length synthesized here is similar to 70 mu m, which is considerably longer than that obtained in the conventional AgNO3/HF/H2O system (similar to 30 mu m). The aligned SiOx nanowires are also synthesized by heating the SiNWs in air ambient at 1200 degrees C for 10 min. Although no light emission is observed from the SiNWs, the oxidized sample emits light in the blue region. (C) 2010 The Electrochemical Society. [DOI: 10.1149/1.3436643] All rights reserved.