Metal nanohelix arrays have been fabricated using glancing angle deposition. Comparing with method of substrate patterning, nanohelices with average arm width of 32 nm, pitch length of 34 nm and radius of curvature around 12.5 nm grew on a regular seeded layer with period of 79 nm and average seed diameter of 14 nm. In order to mass produce metal nanohelices, smooth substrates were adopted to deposited nanohelix arrays. Due to shadowing effect achieved under substrate cooling, the silver and gold nanohelix arrays could be grown successfully on smooth substrates by well controlling the substrate spin rate with respect to the deposition rate. In this work, the thickness of deposition monitored by quartz monitor was kept at 0.3 nm/s. The substrate was cooled to a low temperature around -10oC. The average arm width, pitch length, radius of curvature and spacer between nanohelices vary with deposition angle are investigated here. The morphology of nanohelix varies with different deposition angles (from 86o to 80o) were also to be investigated. In this work, the average space between adjacent nanohelices and radius of curvature were reduced and increased by increasing the deposition angle, respectively. The average pitch of each nanohelix array was low dependent on the deposition angle. The overlap effect occurs between adjacent nanohelices and the gaps between nanohelices support local field enhancement. The area associated local field enhancement called hot spots. Surface-enhanced Raman scattering (SERS) signals from nanostructured thin films were measured and compared with near-field simulations.
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Study of self-shadowing effect as a simple means to realize nanostructured thin films and layers with special attentions to birefringent obliquely deposited thin films and photo-luminescent porous silicon