Repeatable Silicon Nanowires Transfer to Flexible Substrate by Two-Step Metal Assisted Chemical Etching

We reported a two-step gold (Au)-assisted chemical etching for Si nanowires (SiNWs) transfer on a flexible substrate. The first step is for making vertical SiNWs and the second step is for the fracture at the bottom of SiNWs, allowing an easy transfer of the fractured SiNWs to a receiving flexible substrate. The nanoimprint lithography (NIL) was performed to generate periodically aligned chromium (Cr) dots, which were inert to the following chemical etching step, covered with an Au film. Meanwhile, only the silicon part underneath the Au film was selectively etched, resulting in spatially isolated SiNWs at a certain pitch. Repeatable production and transferring of the SiNWs were also demonstrated. In addition, porous SiNWs were produced by additional etching with Ag nanoparticles adhered to the side wall of SiNWs for the higher surface to volume ratio.