Roles of crystal defects in site-controlled preparation of metallic micro/ nanostructures on silicon surface

Metallic micro/nanostructures are core components for building high-performance sensors and circuits. Nanoscratches on silicon (Si) surface have been demonstrated to induce the orientational deposition of metals; however, the effect of crystal defects on deposition remains unclear, which raises difficulties for preparing highquality metallic micro/nanostructures. Herein, a site-controlled preparation strategy was proposed for obtaining high-grade Au micro/nanostructures on Si nanoscratches with the assistance of photoresist mask. The roles of Si oxide, amorphous Si (a-Si), and distorted Si were systematically investigated toward optimal preparation, and the involved mechanisms were further revealed based on surface conductivity detection and electron migration analysis. It was found that the scratch after removing top Si oxide and a-Si layers can facilitate the formation of compact Au structures. Further analysis indicated that Si oxide and a-Si can hinder electron migration in the scratched area, while distorted Si can promote electron migration which is more conducive to the redox reaction. The excellent practical applicability was demonstrated by detecting surface-enhanced Raman scattering spectra of malachite green molecules absorbed on the obtained Au line-structure arrays. Moreover, the prepared Au structures on Si can be mechanically transferred onto PDMS surface. This study opens a new road in the facile and cost-effective preparation of metallic micro/nanostructures, which are promising for extending microsensors applications.