Photochemical etching of silicon

M. L. Ngan*, K. C. Lee, Kok Wai CHEAH

*Corresponding author for this work

Research output: Contribution to journalConference articlepeer-review

5 Citations (Scopus)


Silicon that was immersed in hydrofluoric acid can be etched photochemically by laser, and it was found to produce long and regular columnar structure, if the laser power density is greater than 10 mW/mm2. Another criterion is that the laser wavelength should be at the blue end of visible spectrum. Fine wires with diameter 300-200 nm were also observed at the top of these columns. The dimension of these fine wires is near to quantum confinement dimension, thus can be taken as supporting evidence for quantum confinement. The photoluminescence spectra full width half maximum was narrower than that from porous silicon fabricated from conventional anodization method. The narrower full width was attributed to the uniformity of the porous silicon structure. A physical model is proposed to explain the observed strong directional etching. The model showed that once the etch sites have randomly initiated, the etching rate becomes directional under the influence of laser. The intensity of laser controls the etching direction such that silicon columns are formed if the intensity of the laser is strong enough.

Original languageEnglish
Pages (from-to)41-45
Number of pages5
JournalJournal of Porous Materials
Issue number1
Publication statusPublished - 2000
EventProceedings of the 1998 1st International Conference on Porous Semiconductors - Science and Technology (PSST-98) - Mallorca, Spain
Duration: 16 Mar 199820 Mar 1998

Scopus Subject Areas

  • Materials Science(all)
  • Mechanics of Materials
  • Mechanical Engineering


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