Ferromagnetic Co-doped ZnO thin films grown using pulsed laser deposition from Zn and Co metallic targets

We report the synthesis of high-quality Co-doped ZnO thin films using the pulsed laser deposition technique on (0 0 0 1)-Al2O3 substrates under an oxidizing atmosphere, using Zn and Co metallic targets. The growth of ZnO was optimized in order to obtain the least strained film using the sin2 Ψ model. Highly crystallized Co:ZnO thin films are obtained by an deposition from alternating Zn and Co metal targets. This procedure results in homogenous incorporation of the Co in the ZnO wurtzite structure, which is confirmed by the linear dependence of the out-of-plane lattice parameter as a function of the Co dopant up to 9%. The Zn1−xCoxO films exhibit ferromagnetism with a Curie temperature close to room temperature for x=0.08 and at 150 K for x=0.05.