Authors: J. Neamtu, C. Teodorescu, G. Georgescu, J. Ferré, T. Malaeru, I. Jitaru
Affilation: National Institute for Research&Development in Electrical Engineering, Romania
Pages: 238 - 241
Keywords: thin film, diluted magnetic semiconductor, sol-gel, X-ray absorption near-edge structure, Kerr effect
Co doped ZnO thin film has promising potential for spintronic devices. Theoretical calculations predict ferromagnetism for Diluted Magnetic Semiconductors (DMS): ZnO doped with transition metals (Fe,Co,Ni). We have investigated Co (x=0.05-0.30) doped ZnO (Zn1-xCoxO), films were grown on (100) silicon and Corning glass by sol-gel process. A homogeneous and stable Zn1-xCoxO sol was prepared by dissolving zinc nitrate hexahydrate, cobalt acetate in a PVP (polyvinylpyrrolidone) solution. The thin films grown by spin coating method were heated in nitrogen at 8000C for 30 min. Zn1-xCoxO thin films with different Co concentrations were well oriented along the c-axis, but especially the thin film at 30 % Co concentration. The structures of Co-doped ZnO films were investigated by XRD. The local structure studies of our Zn1-xCoxO thin films by XANES (X-ray absorption near-edge structure) and EXAFS (extended x-ray absorption fine structure) prove the formation of metallic Co nanoclusters. Most of Co atoms (around 87 %) are placed in environments similar to that of Co(II) oxide and quite a few (around 13 %) are substituting Zn in the ZnO lattice. The Magneto-Optical Kerr Effect (MOKE) studies of Co doped ZnO films show a weak ferromagnetic behavior at room-temperature.