Precise tuning of the photonic band gap using multilayered inverse opals
2014 (English)In: 12th Russia/CIS/Baltic/Japan Symposium on Ferroelectricity and 9th International conference on Functional Materials and Nanotechnologies – RCBJSF–2014-FM&NT / [ed] A. Sarakovskis, Ulma, Riga , 2014Conference paper, Abstract (Refereed)
Inverse opals are photonic band gap (PBG) structures with a periodic arrangement of voids with low refractive index (air) in a high-refractive index dielectric media with sub-wavelength periodicity. In analogy with electronic band gaps in solid state semiconductors these structures form forbidden energy ranges for light, irrespective of the photon’s momentum. Recently, inverse opal structures have been studied for photocatalysis applications. Here the idea is to match the edge of the PBG with the electronic band gap of a semiconductor to allow for efficient light absorption. Here we present a novel approach to tune the position and shape of the PBG by purposefully deposit multilayers of oxides with controlled thicknesses on the inside walls of the inverse opals. This avoids the technical problems of changing the periodicity and materials of the opals. The fabrication involves a three-step process: It consists of self-assembly by convective evaporation of polystyrene beads into close-packed fcc structures; atomic layer deposition (ALD) of metal oxides (Al2O3) to fill the voids between the beads; and subsequent Ar ion etching and calcination to crystallize and develop the inverse opal structure. ALD is then repeated to make multi-layer structures of TiO2 with controlled thickness. The inverse opal structures were characterized by optical spectroscopy, X-ray spectroscopy, electron microscopy, and profilometry. Theoretical modeling was performed to describe the optical properties. The results are analyzed and compared with band structure calculations made by the plane-wave expansion method together with finite-difference time-domain simulations of the transmission spectra (Fig. 1). Our method is versatile and can be used to fabricate reactive nanoparticles with different chemical composition on the inside walls; as well as plasmonic nanoparticles embedded in the layers to efficiently absorb slow light.
Place, publisher, year, edition, pages
Ulma, Riga , 2014.
Engineering and Technology Physical Sciences Nano Technology Chemical Engineering
Research subject Physics; Engineering Science with specialization in Nanotechnology and Functional Materials
IdentifiersURN: urn:nbn:se:uu:diva-238306OAI: oai:DiVA.org:uu-238306DiVA: diva2:770842
12th Russia/CIS/Baltic/Japan Symposium on Ferroelectricity and 9th International conference on Functional Materials and Nanotechnologies – RCBJSF–2014-FM&NT, Sept 29 - Oct 2 2014, Riga, Latvia
FunderSwedish Research Council, 2010-3514