Figure 3
From: Freestanding HfO2 grating fabricated by fast atom beam etching
SEM images of fabricated freestanding HfO 2 nanostructures. (a) SEM image of a freestanding circular HfO2 grating, the inset is the zoom-in SEM image of circular grating with the grating period of 500 nm; (b) a freestanding HfO2 photonic crystal slab on a GaN-on-silicon platform, the inset is the zoom-in SEM image of HfO2 photonic crystals with the grating period of 600 nm.