3D luminescent photonic crystal structures

We report the fabrication of photonic crystal phosphors by atomic layer deposition and the subsequent removal of self-assembled opal templates. ZnS:Mn and TiO ₂ inverse opals as well as ZnS:Mn/TiO ₂ composite inverse opals were formed. Shifts in the Γ-L photonic band gap positions were confirmed by reflectivity and transmission measurements and were consistent with photonic band structure calculations. The peak positions confirm that filling terminates at ∼86% of the pore volume in agreement the maximum possible filling fraction for the "shell" infiltration of an opal structure. For TiO ₂ depositions, SEM and AFM analysis reveals ultra-smooth highly conformal films. In addition, infiltration control to < 1 nm was achieved, making fine-tuning of PC properties possible. Significant changes were observed in the emission characteristics for composite ZnS:Mn/TiO ₂ photonic crystals. This work demonstrates that precisely controlling the placement of materials is possible by ALD, enabling the fabrication of "optimized" structures, including those which modify emission properties.