Enhancement in visible luminescence from nanocomposite ZnO-SiO_x thin films due to annealing

Abstract

The annealing induced enhancement in visible photoluminescence (PL) from nanocomposite (nc) ZnO-SiO x thin films was investigated. Nc ZnO-SiO x thin films consisting of ZnO nanocrystals in silica matrix were grown by depositing the films using radio frequency (rf) reactive co-sputtering and post-annealing them at temperatures of 350 ○ C and 500 ○ C in high vacuum and air. These films were characterized by Fourier transform infrared (FTIR), (PL) spectroscopy and UV-Vis spectrophotometry measurements. Thin films were also deposited on transmission electron microscopy (TEM) grids in almost identical conditions. The TEM measurement of the thin film deposited on TEM grid shows the formation of ZnO nanocrystals with a size distribution from 3.0 nm to 6.8 nm (þ=À0.2 nm) in silica matrix. The UV-Vis spectra of the films show absorption features of ZnO and Zn 2 SiO 4 phases in the films. The visible PL emission intensity and peak width increased in the annealed films. The results suggest increase in the number and size distribution of the ZnO nanocrystals in silica matrix due to the annealing resulting in increase in visible PL emission. The results of vacuum annealed films indicate that these films can be useful in the development of wide band visible light emitting devices using this material.

Effect of 750keV Argon ion irradiation on nc ZnOSiOx thin films

“…Both these processes can cause the drastic decrease in visible PL emission from ZnO, which was observed for the irradiated nc ZnO SiO x films. Further, the visible luminescence from SiO x phase that occurs at 630 nm in nc ZnO SiO x thin films [14] also decreased drastically. This suggests that the damage produced by 750 keV argon ions in the SiO x phase, as observed in FT-IR studies, has caused decrease in transition between the triplet states (T2−T1) in the SiO x phase, possibly due to decrease in optical absorption at 2.0 eV.…”

Efficient energy transfer from zinc oxide nanocrystals to europium (3+) and terbium (3+) ions embedded in an oxide matrix

“…Thin films of ZnO-nc in SiO 2 or Eu 3+ /Tb 3+ and ZnO-nc in SiO 2 can be prepared using most of the thin film deposition techniques mentioned above. For instance, sputtering [120][121][122][123], ion implantation [124], plasma enhanced chemical vapour deposition (PECVD) [125] and sol-gel process [9,25,28,[126][127][128][129] have been used by various groups to deposit thin film samples of semiconductor nanocrystals and rare-earth ions. Most of these thin film deposition techniques are complex processes which require sophisticated fabrications systems.…”