Metal-assisted chemical etching of GaAs using Au catalyst deposited on the backside of a substrate

GaAs line patterns and pillar arrays were fabricated by metal-assisted chemical etching using Au thin films deposited on the backsides of substrates. After Au was deposited on the substrate backsides, the specimens were coated with shape-controlled resist masks and were etched in mixed solutions of H2SO4 and KMnO4, resulting in the formation of ordered line patterns and pillar arrays on the GaAs substrates. The Au thin films, which served as catalysts, were not deformed or delaminated during the etching process. This method offers a new route to fabricate complex three-dimensional GaAs structures.