Correlation among lattice strain, defect formation and luminescence properties of transition metal doped ZnO nano-crystals prepared via low temperature technique

The present study focuses on the structural-optical correlation of dilute Fe doped ZnO nano-particles synthesized via low temperature chemical route. Polycrystalline Hexagonal wurtzite structure was confirmed from x-ray diffraction. Lattice parameters calculated using the Scherrer's method are appended with substitutional doping induced deformations, leading to dopant-defect induced broadening, lattice strain and decreased crystallanity using modified W-H analysis. The direct correlation of the peak broadening with defect formation, contraction and expansion of band gap is carried out. The mechanism responsible for the formation of defects, lattice strain and shifting of band gap due to finite size effect of dopant is discussed. The presence of such defects is confirmed from the Photoluminescence spectroscopy. CIE coordinates indicate emission in blue region with variation from cool to warm under the UV excitation. Thus, making them promising candidates for the use as cost-effective phosphors in UV-blue region and in down conversion based luminescent devices.