3D Double‐Layer Suspended Nanostructures Fabricated via Plasma‐Assisted Nanotransfer Printing

Abstract Suspended nanostructures have found widespread applications (e.g., photodetectors, displays, and sensors) due to their unique properties, such as high surface‐to‐volume ratio (H‐SVR), high mass transport, and low‐power etc. Various suspended nanostructures have been fabricated using existing nanofabrication techniques (e.g., electron beam, optical lithography, and layer‐by‐layer assembly). However, realizing the fabrication of double‐layer suspended nanostructures remains a significant challenge. Herein, a method for fabricating large‐area, uniform, and well‐arrayed double‐layer suspended nanostructures is presented using plasma‐assisted nanotransfer printing (PA‐nTP). Double‐layer nanostructures are prepared via nanoimprint lithography and e‐beam evaporation. Oxygen plasma treatment reduces the bonding force between the nanoimprinted resin, allowing gold nanodots suspended atop nanohole structures to be transferred onto the silicon (Si) substrate. The developed structures serve as substrates for surface‐enhanced Raman scattering (SERS) and templates for hollow Si nanostructures. The Au‐coated 3D double‐layer suspended nanostructures enhance SERS performance by a factor of 1.5 × 10 6 compared to flat substrates. Additionally, hollow Si nanostructures fabricated through metal‐assisted chemical etching (MACE) improve the hydrogen (H 2 ) sensor response from 2.54% to 165% under 1% H 2 , compared to solid Si nanostructures. Therefore, this method provides a feasible pathway for advancing nanofabrication in applications such as biological/chemical sensors and optoelectronics.