Embedded air and solid defects in periodically structured porous thin films

摘要

Highly porous thin films with columnar microstructures are applicable to many optical, chemical, and electronic devices, and can be fabricated using the glancing angle deposition method for physical vapour deposition onto tilted substrates. In a recent advancement of this method, it was shown that decoupling of the vapour incidence direction from the column growth direction provides significant flexibility to engineer the pore structure of the films. Here we elaborate on the decoupling principle by applying it to chiral thin films with a periodic microstructure, and demonstrating how it leads to improved film uniformity and the elimination of column broadening. We also show the effects of such depositions onto substrate seed layers with intentional defects. Substrate based defects normally transfer to thin films as air filled defects, but here we present for the first time that a simple adjustment of the deposition parameters can invert the normally air filled defects to become solid, evaporant filled defects. This defect engineering capability provides new opportunities for the deployment of glancing angle deposition thin films to photonic bandgap crystals and microfluidic devices.