Structural and magnetic properties of Co-doped ZnO films grown by pulse-injection MOCVD

We report on pulse-injection metal organic chemical vapor deposition (PI-MOCVD) and characterization of Zn1-xCoxOZn1-xCoxO films on (1 1 0 2) sapphire substrates. The use of Zn(tmhd)2 and Co(tmhd)3 precursors produces high-quality films in which Co2+2+ ions replace Zn2+ without disrupting the ZnO lattice. The Zn1-xCoxOZn1-xCoxO films are magnetic at room temperature for x⩽0.10x⩽0.10 and the magnetic moments are particularly large for small Co doping concentrations (18.9μB/Co for x=0.01x=0.01 and 6.5μB/Co for x=0.02x=0.02). These large moments and the decrease of the saturation moment with increasing Co content cannot be explained by the formation of Co clusters. We instead believe that the magnetic behavior of the PI-MOCVD grown samples is an intrinsic property of the Zn1-xCoxOZn1-xCoxO films.