Structural, optical and magnetic properties of Co-doped ZnO films

Zn1−xCox  O (x=0.05x=0.05, 0.1, 0.15) films were deposited on Si (1 0 0) and quartz glass substrates using inductively coupled plasma enhanced physical vapor deposition system with magnetic confinement. Structural and chemical composition characterizations by X-ray absorption spectroscopy and Rutherford backscattering spectroscopy indicate that Co2+ substitute for Zn2+ in the tetrahedral configuration and form homogeneous films with wurtzite structure when x⩽0.15. UV–vis transmittance spectra are used to characterize the optical properties. It is found that both transmittance and band gap of Zn1−xCoxO films decrease with increasing Co content, owing to the enhancement of sp–d exchange interactions and typical d–d transitions. Magnetic measurements show that all the as-grown films exhibit intrinsic ferromagnetism above room temperature.