Modifying the Morphology of Silicon Surfaces by Laser Induced Liquid Assisted Colloidal Lithography

Magdalena Ulmeanu, Robert L Harniman, P. Petkov, Michael N R Ashfold

Research output: Contribution to journalArticle (Academic Journal)

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Abstract

Single, or isolated small arrays of, spherical silica colloidal particles (with refractive index ncolloid = 1.47 and radius R = 350 nm or 1.5 μm) were placed on a silicon substrate and immersed in carbon tetrachloride (nliquid = 1.48) or toluene (nliquid = 1.52). Areas of the sample were then exposed to a single laser pulse (8 ps duration, wavelength λ = 355 nm), and the spatial intensity modulation of the near field in the vicinity of the particles revealed via the resulting patterning of the substrate surface. In this regime, ncolloid < nliquid and the near-field optical intensification is concentrated at and beyond the edge of the particle. Detailed experimental characterization of the irradiated Si surface using atomic force microscopy reveals contrasting topographies. The same optical behavior is observed with both liquids, i.e., the incident laser light diverges on interaction with the colloidal particle, but the resulting interaction with the substrate is liquid dependent. Topographic analysis indicates localized ablation and patterning of the Si substrate when using toluene, whereas the patterning induced under carbon tetrachloride is on a larger scale and extends well below the original substrate surface—hinting at a laser induced photochemical contribution to the surface patterning
Original languageEnglish
Article number1306
Number of pages6
JournalMaterials
Volume10
Issue number11
Early online date14 Nov 2017
DOIs
Publication statusPublished - Nov 2017

Keywords

  • colloids
  • laser processing
  • patterning
  • liquid induced photochemistry

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