Development of interference filters based on multilayer porous silicon structures

Development of interference filters based on multilayer porous silicon structures

Torres-Costa, V.; Gago, R.; Martín-Palma, R. J.; Vinnichenko, M.; Groetzschel, R.; Martínez-Duart, J. M.

Porous silicon (PS) has a great potential in optical applications due to its tuneable refractive index. In particular, multilayer structures consisting on PS layers with different refractive indexes can be used as interference filters. Due to the characteristics of PS and its production process, many types of interence filters can be produced: Bragg reflectors, monochromatic filters for light emitting devices (which can also be based on PS), microcavities for biosensing applications, Fabry-Pérot resonators, photonic crystals, etc.

In the present work the optical properties of PS single layers and multilayer structures were studied. Since the refractive index of PS varies depending on the air content of the porous matrix, the PS structures were modelled as an homogeneous mixture of silicon and air (and, eventually, silicon dioxide), according to the effective medium theories (EMTs). By adjusting the refractive index and thickness of each individual layer, we can obtain a stack of PS layers with the desired optical properties, resulting in interference filters of predetermined band width.

The optical characterization has been carried out by spectrophotometric and spectroscopic ellipsommetry measurements. In addition, compositional analysis has been performed by means of Ion Beam Analysis (IBA) techniques, with special interest devoted to oxygen and hydrogen, in order to correlate the optical parameters and the chemical composition. Finally, multilayers structures have been produced and their operation has been checked.

  • Poster
    E-MRS 2003 Spring Meeting, 10-13 June 2003, Strasbourg (France)
  • Materials Science and Engineering C 23 (2003) 1043-1046

Publ.-Id: 5585