Diluted magnetic semiconductor properties in Zn_1−xCu_xO nanoparticles synthesized by sol gel route

Nanoparticles of ZnO:Cu Diluted Magnetic Semiconductor (DMS) are prepared using sol gel method. The structural, optical and EPR properties of them are investigated. The XRD patterns of them show the formation of polycrystalline and hexagonal wurtzite structure without any secondary phase formation. The average size of particles ranges from 14 to 19 nm. In the optical absorption study of the samples, a red shit of optical band edge and a narrowing of the optical band gap are observed when Cu concentration is increased. The PL measurements illustrate 392 nm UV radiation of the near band-edge emissions of ZnO, blue emission at 450 nm and orange emission at 628 nm. The cause of decrease in intensity of these emission lines is the sincerely enhanced non-radiative transitions when Cu is doped in ZnO. EPR measurements provide substantial evidence for the presence of defect states and enhancement of exchange interaction.