A feasible and low-cost green route to prepare ZnO with n or p-type conductivity by changing the parsley extract concentration

Abstract

ZnO samples were prepared by an easy process based on green synthesis using three different concentrations of the parsley extract as natural reducing agents. The semiconductors were characterized structural, morphological, and opto-electronically by XRD, SEM-EDS, diffuse reflectance, and photo-response, respectively. Hexagonal structure ZnO-based semiconductors were obtained after the annealing process at 400ºC. The morphology, bandgap, and photo-response of the synthesized samples were sensitive to the extract concentrations used in this work. The incorporation of Mg traces in the bulk of ZnO produced changes in the c-lattice parameter, consequently forming native defects such as Oi and Vo. The bandgap increased as the Mg content in the ZnO increased too. The photo-response analysis suggested that the samples with 0.44 and 1.33 at% of Mg were p-type ZnO, while the sample with 2.01 at% was n-type ZnO. It likely means that the conductivity type and other optoelectronic characteristics depend on the Mg content in the ZnO samples and the formation of predominant native defects due to the interaction of Mg with the crystalline structure.