Defects induced luminescence and tuning of bandgap energy narrowing in ZnO nanoparticles doped with Li ions

Abstract

Microstructural and optical properties of Zn 1Ày Li y O (0.00 y 0.10) nanoparticles are investigated. Li incorporation leads to substantial changes in the structural characterization. From micro-structural analysis, no secondary phases or clustering of Li was detected. Elemental maps confirmed homogeneous distribution of Li in ZnO. Sharp UV peak due to the recombination of free exciton and defects based luminescence broad visible band was observed. The transition from the conduction band to Zinc vacancy defect level in photoluminescence spectra is found at 518 6 2.5 nm. The yellow luminescence was observed and attributed to Li related defects in doped samples. With increasing Li doping, a decrease in energy bandgap was observed in the range 3.26 6 0.014 to 3.17 6 0.018 eV. The bandgap narrowing behavior is explained in terms of the band tailing effect due to structural disorder, carrier-impurities, carrier-carrier, and carrier-phonon interactions. Tuning of the bandgap energy in this class of wide bandgap semiconductor is very important for room temperature spintronics applications and optical devices. V C 2014 AIP Publishing LLC.[http://dx

Structural, Morphological, Optical, and Room Temperature Magnetic Characterization on Pure and Sm-Doped ZnO Nanoparticles

“…On the other hand, the lattice parameters decreased for x = 0 01, 0.06, and 0.08 relative to pure ZnO. Decrease in lattice parameters is expected when Sm substitutes Zn while the lattice parameter will increase when Sm occupies interstitial sites [42]. The ratio (c/a) is approximately 1.60 for all samples which is compatible with the ideal value for hexagonal cell (c/a = 1 633) [43].…”

The investigation of mechanical and dielectric properties of Samarium doped ZnO nanoparticles

“…However, the lattice constants decreased for x=0.01, 0.06, and 0.08 with respect to pure ZnO. Decrease in lattice parameters is expected when Sm substitutes Zn while the lattice parameter will increase when Sm occupies interstitial sites [26,28]. clearly shows an agglomeration of the prepared nanoparticles for a high doping level of Samarium with x=0.10 [26].…”

Structural and Optical Characteristics of Highly UV-Blue Luminescent ZnNiO Nanoparticles Prepared by Sol–Gel Method

“…It can be seen from the pure ZnO (reference sample) that the PL spectra are mainly comprised of UV emission peaks at 3.34 eV (370 nm) followed by a high-intensity broad visible band with multiple sub-peaks in the range of 2.1-2.75 eV (450-590 nm). The UV emission is attributed to the recombination of free excitons in the near band edge (NBE) of ZnO, whereas the visible band is generally interpreted as the reason for the defects [8,[50][51][52][53]. Meanwhile, the origins of different visible emissions are still not fully assumed and different controversial hypotheses have been offered [8,[50][51][52][53].…”

“…The UV emission is attributed to the recombination of free excitons in the near band edge (NBE) of ZnO, whereas the visible band is generally interpreted as the reason for the defects [8,[50][51][52][53]. Meanwhile, the origins of different visible emissions are still not fully assumed and different controversial hypotheses have been offered [8,[50][51][52][53]. In our case, the emission features at 2.43 eV (510 nm) and 2.21 eV (560 nm) are related to antisite oxide (OZn) and to transmission from conduction band to vacancy, respectively.…”