Recycling Si wafers to fabricate multiple Si nanohole thin films by metal-assisted etching

Si nanostructures are promising materials for future photovoltaic applications. To date the Si nanostructures are mainly formed on particular substrates or at high temperatures, greatly limiting their application flexibility. Here we report a two-step metal-assisted etching technique for forming vertically aligned Si nanohole thin films on bulk Si wafers at room temperature. The Si nanohole thin films with a thickness of 5μm can be easily transferred to alien substrates. Because of the low temperature transfer process, it enables a large variety of alien substrates such as glass and plastics to be used. In addition, we demonstrate that the bulk Si substrate can be reused to fabricate Si nanohole thin films. The consumption of bulk Si materials is significantly reduced.