Figure 2.

SEM and AFM images of opal-like photonic crystals and the bandgap zone. Respective SEM (a, b) and AFM (c) images of thin (a) and thick (b, c) opal-like photonic crystals formed by depositing 200-nm silica spheres by spin coating on a silicon substrate. (d) The bandgap zone centered around 500 nm as revealed from the reflectance spectrum.

Tsvetkov et al. Nanoscale Research Letters 2013 8:250   doi:10.1186/1556-276X-8-250
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