Advanced Optical Filters of Porous Silicon

  • Gerhard Lammel
  • Sandra Schweizer
  • Philippe Renaud
Part of the Microsystems book series (MICT, volume 14)

Abstract

Porous silicon is fabricated by electrochemical etching of monocrystalline silicon in hydrofluoric acid (HF). A multilayer dielectric interference filter of porous silicon is based on the effect that the index of refraction depends on the degree of porosity, which can be chosen individually for every layer by the fabrication process. The porosity, i.e. the ratio of void volume to total volume in the layer, depends on the current density during the layer formation by electrochemical etching. To fabricate an optical filter the etch current is varied over time according to the desired refractive index profile of the layer stack. With this technology, optical filters of porous silicon can be produced within minutes in a single process step that generates a modulated density (Fig. 6.1).

Keywords

Porous Silicon Porous Layer Critical Current Density Optical Filter Index Profile 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

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Copyright information

© Springer Science+Business Media New York 2002

Authors and Affiliations

  • Gerhard Lammel
    • 1
  • Sandra Schweizer
    • 1
  • Philippe Renaud
    • 1
  1. 1.Swiss Federal Institute of Technology LausanneEPFLSwitzerland

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