Nanostructuring HfO2 Thin Films as Antireflection Coatings

Hafnium dioxide (HfO2) films deposited on silicon substrates can be nanostructured by the glancing angle deposition technique into various porous morphologies, leading to a variation of the refractive index in a range of 1.94-1.16. This makes HfO2 thin films effective antireflection coatings on many substrates. For example, a 160-nm-thick HfO2 film of an appropriate refractive index can cut more than half the reflection of visible light off the surface of SiC or Al2O3 substrates. This study provides an easy way to design, prepare, and optimize the performance of antireflection coatings on different substrates.