The structure, optical and magnetic properties of arsenic implanted ZnO films prepared by molecular beam epitaxy

Different concentrations of arsenic ions have been introduced into high quality O polar ZnO films prepared by rf-plasma assisted molecular beam epitaxy on sapphire substrates by ion implantation. Rutherford Backscattering/Channeling, x-ray diffraction, Raman spectroscopy and optical absorption measurements have been carried out to characterize the implantation induced disorder in the ZnO films. Room temperature ferromagnetism has been observed for the films implanted with As dose higher than 6×1018 cm−3. The size of the observed moment is too large to be attributed to the As related defect complex (AsZn-2VZn) and is attributed to defects introduced by the ion implantation process. This was confirmed by the observation that the magnetization could be removed by annealing the films.