Optical properties of ZnO nanocrystals embedded in BaF₂ film fabricated by magnetron sputtering

Abstract

ZnO nanocrystals (NCs) embedded in a BaF2 matrix have been prepared by a radio-frequency magnetron sputtering technique followed by a thermal annealing process from 400 to 1100 °C. X-ray diffraction results show that ZnO NCs with a hexagonal wurtzite structure are formed in a BaF2 matrix. The average grain sizes are estimated ranging from 7.5 to 33 nm, corresponding to fabricated samples annealed at temperatures from 400 to 800 °C. Photoluminescence showed a very strong ultraviolet near-band-edge (NBE) emission located in the 364–383 nm spectral region. The emission intensity is enhanced and the linewidth is narrowed as the annealing temperature increases. The intensity ratio of ultraviolet NBE emission to deep-level visible is also increased with annealing temperature indicating that deep-level defects in ZnO are suppressed.

Enhanced ultraviolet emission from highly dispersed ZnO quantum dots embedded in poly(vinyl pyrrolidone) electrospun nanofibers

“…From Fig. 5, it was well established that the size of ZnO QDs could be estimated from the excitonic absorption peak based on the effective mass approximation [15,35].…”

“…It is great challenge to enhance the ultraviolet (UV) emission of nanostructural ZnO materials. Thus, in recent years, the optical properties of ZnO nanocrystals embedded in organic polymers, such as poly(vinyl alcohol) (PVA), poly(methyl methacrylate) (PMMA) and poly(vinyl pyrrolidone) (PVP) [9][10][11], and inorganic materials, such as CaF 2 , MgO, SiO 2 and BaF 2 [12][13][14][15], have been widely studied. Especially, polymer/ZnO nanocrystals composites with one dimensional (1D) nanostructure have been of immense interest because of their large length-to-diameter ratio, special optical and conductivity properties, and so forth, which might be very useful to fabrication of nanoscale electronic and optoelectronic devices.…”