Nonaqueous sol-gel chemistry applied to atomic layer deposition: tuning of photonic band gap properties of silica opals


Combining both electromagnetic simulations and experiments, it is shown that the photonic pseudo band gap (PPBG) exhibited by a silica opal can be fully controlled by Atomic Layer Deposition (ALD) of titania into the pores of the silica spheres constituting the opal. Different types of opals were assembled by the Langmuir-Blodgett technique: homogeneous closed packed structures set up of, respectively, 260 and 285 nm silica spheres, as well as opal heterostructures consisting of a monolayer of 430 nm silica spheres embedded within 10 layers of 280 nm silica spheres. For the stepwise infiltration of the opals with titania, titanium isopropoxide and acetic acid were used as metal and oxygen sources, in accordance with a recently published non-aqueous approach to ALD. A shift of the direct PPBG, its disappearance, and the subsequent appearance and shifting of the inverse PPBG are observed as the opal is progressively filled. The close agreement between simulated and experimental results is striking, and promising in terms of predicting the properties of advanced photonic materials. Moreover, this work demonstrates that the ALD process is rather robust and can be applied to the coating of complex nanostructures.



subject category

Chemistry; Science & Technology - Other Topics; Materials Science; Physics


Marichy, C; Dechezelles, JF; Willinger, MG; Pinna, N; Ravaine, S; Vallee, R

our authors



This work was partially supported by the European Network of Excellence FAME and the WCU (World Class University) program through the National Research Foundation of Korea funded by the Ministry of Education, Science and Technology (R31-10013). We thank A. Klein from Fritz-Haber-Insitute (FHI) in Berlin, B. Agricole (CRPP) and E. Sellier (Centre de Ressources en Microscopie Electronique, Talence, France) for the TEM cross section preparations, Langmuir-Blodgett experiments and SEM observations, respectively. M. W. acknowledges Prof. R. Schloegl and the Fritz-Haber-Insitute (FHI) in Berlin for using the electron microscope.

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