Tantalum(V) nitride inverse opals as photonic structures for visible wavelengths

The development of materials with a complete photonic band gap at visible wavelengths is believed to have the potential to lead to new control over long-lived emissive excited states, single molecule lasers, and nearly lossless nanoscale waveguides. In this work we move toward that goal with the synthesis of an inverse opal thin film of Ta3N5 produced through atomic layer deposition. The highly regular architecture achievable by atomic layer deposition is combined with an unusually high refractive index and transparency in at least part of the visible spectrum. The result is a material that represents the closest example to date of a photonic crystal with a band gap at optical wavelengths.