In this study we report etched-GaAs morphologies with noble-metal layers embedded in the etching structures that are prepared by a simple wet process. Well-controlled n-GaAs (100) hole arrays are formed through metal-assisted chemical etching using a sputtered Au layer as an etching catalyst. GaAs exhibits anisotropic etching behavior, which originates from the substrate crystallography. The configuration of hole arrays is determined by the concentration of hydrofluoric acid included in the etching solution, the arrangement of Au catalysis layers relative to the preferential etching direction of the GaAs (100) substrate, and the etching time. The relationship between the etching process and the resultant hole structure is also discussed. (C) 2012 The Electrochemical Society. [DOI: 10.1149/2.021206jes] All rights reserved.