Homogeneous Nanostructured VO₂@SiO₂ as an Anti-Reflecting Layer in the Visible/Near Infrared Wavelength

Low reflectivity is of great significance to photoelectric devices, optical displays, solar cells, photocatalysis and other fields. In this paper, vanadium oxide is deposited on pattern SiO₂ via atomic layer deposition and then annealed to characterize and analyze the anti-reflection effect. Scanning electron microscope (SEM) images indicate that the as-deposited VO_x film has the advantages of uniformity and controllability. After annealing treatment, the VO₂@pattern SiO₂ has fewer crevices compared with VO₂ on the accompanied planar SiO₂ substrate. Raman results show that there is tiny homogeneous stress in the VO₂ deposited on pattern SiO₂, which dilutes the shrinkage behavior of the crystallization process. The optical reflection spectra indicate that the as-deposited VO_x@pattern SiO₂ has an anti-reflection effect due to the combined mechanism of the trapping effect and the effective medium theory. After annealing treatment, the weighted average reflectance diminished to 1.46% in the visible near-infrared wavelength range of 650-1355 nm, in which the absolute reflectance is less than 2%. Due to the multiple scattering effect caused by the tiny cracks generated through annealing, the anti-reflection effect of VO₂@pattern SiO₂ is superior to that of VO_x@pattern SiO₂. The ultra-low reflection frequency domain amounts to 705 nm, and the lowest absolute reflectance emerges at 1000 nm with an astonishing value of 0.86%. The prepared anti-reflective materials have significant application prospects in the field of intelligent optoelectronic devices due to the controllability of atomic layer deposition (ALD) and phase transition characteristics of VO₂.