Structural, bandgap tuning and electrical properties of Cu doped ZnO nanoparticles synthesized by mechanical alloying

Cu doped ZnO nanoparticles abbreviated as Zn1-xCuxO (x = 0, 0.01 and 0.03) were synthesized by mechanical alloying. The change in structure, morphology, band gap and dielectric properties of the synthesized nanoparticles were investigated by XRD, FE-SEM, FTIR, UV-Vis and impedance analyzer respectively. The incorporation of the dopant Cu into ZnO hexagonal wurtzite structure has been verified by X-ray diffraction (XRD) and the Cu doping on the structural bonding of ZnO has been verified by fourier transformation infrared spectra (FTIR). The XRD spectra shows that all the synthesized nanoparticles are single phase, hexagonal wurtzite structure and belong to the space group of P6(3)mc. Crystallite size of Cu doped ZnO (15 nm) nanoparticles is smaller than pure ZnO (18 nm) and peak broadening exists in the system. FESEM analysis indicates that Cu doping affects the surface morphology of ZnO. The band gap (E-g) of ZnO decreases with Cu doping which can be attributed to sp-d exchange interaction between the ZnO band electrons and localized d electrons of Cu2+ ions. The dielectric constant of ZnO decreases with Cu doping.