Highly sensitive waveguide-based porous anodic alumina nanosensors for monitoring atomic layer deposition

A novel optical method for monitoring atomic layer deposition (ALD) is proposed by using porous anodic alumina (PAA) films as planar optical waveguides to measure changes in the effective dielectric constants of these films during TiO₂ ALD. It is shown that the sensitivity of the method is good enough for monitoring ALD growth, and the coupling angle proportionally shifts to the higher value with the increment of the ALD thickness over the film. Our method is applicable to monitor ALD not only on the flat substrate, but also inside the PAA pores.