Structural, optical and magnetic properties of Zn1−xCoxO dilute magnetic semiconductors thin films by pulsed laser deposition

We fabricated Zn1−xCoxO (x=0.05) thin films on sapphire (0 0 0 1) substrates by the pulsed laser deposition (PLD) method at various temperatures in an oxygen-deficient ambient. X-ray diffraction (XRD) spectra, UV–vis transmittance spectra, X-ray photoelectron spectroscopy and photoluminescence (PL) were used for charecterization. All samples possessed the wurtzite structure with the preferential c-axis orientation; PL located at about 418, 450 and 471 nm was observed; Co2+ ions incorporated into the ZnO lattice with substitution for Zn2+ ions, oxygen vacancies, oxygen antisites and Zn interstitials existed in the as-samples. Results of magnetic property of the films investigated by an alternating gradient magnetometer (AGM) indicated that all samples take on room temperature ferromagnetism. It suggested that the ferromagnetism originated from the Co2+–Co2+ exchange interaction related to oxygen vacancies, oxygen antisites and Zn interstitials.