Photoluminescence and IR Properties of Al doped ZnO Nanofibers

Zinc oxide (ZnO) is used widely in electrical and optical applications due to its wide band gap and also semiconductor properties. In the present study ZnO and Al doped (Al/Zn ratio equals to 6 wt.%) nanofibers (NFs) were synthesized by electrospinning method and post calcination at different temperatures 250, 300 and 400 ˚C. The effect of dopant on  microstructure, crystallography, functional molecule groups, and photoluminescence behavior of ZnO NFs were studied by means of scanning electron microscopy (SEM), X-ray diffraction pattern (XRD), Fourier-transform infrared spectroscopy (FTIR), and photoluminescence spectroscopy (PL), respectively. Results showed that the average diameter of ZnO NFs was increased from 131 to 468 nm after calcination. XRD analysis indicated that the hexagonal wurtzite ZnO was formed in both samples. Also it confirmed that the Al dopant was incorporated into ZnO NFs. Comparison of FTIR spectra showed that the Al doping caused to shift the Zn-O band to higher frequencies and also construct the stronger bonds inside the ZnO lattice. PL results also revealed that the Al doping enhanced the optical properties. It is because that the point defects issued by Al doping create lower energy levels for transferring the electrons from conduction band to valence band.