Investigation of ferromagnetism and dual donor defects in Y-doped ZnO thin films

We report here the room temperature ferromagnetism in Y-doped ZnO thin films grown by RF magnetron sputtering. XRD and Raman spectra analysis revealed that pristine and Y-doped ZnO thin films are crystallised in hexagonal wurtzite structure. XPS was performed to confirm the electronic states of elements present in the films. FESEM images of the films were recorded to study their morphological properties. EDAX analysis was also performed to confirm the presence of Y in ZnO thin films. The point defects in the samples were analysed using photoluminescence spectrometer and EPR spectrometer to understand the mechanism behind the magnetic properties exhibited. It is found that zinc interstitial (Zn-i (+)) and oxygen vacancy (V-O (+)) defects coexist in the samples and help in setting ferromagnetic properties in Y-doped ZnO thin films. VSM analysis indicated that Y-doped ZnO thin films show ferromagnetic nature while the pure ZnO thin film exhibits diamagnetic behaviour. The dual donor defect (Zn-i (+) and V-O (+)) assisted bound magnetic polaron model has been proposed to explain the Y-doped ZnO diluted magnetic semiconductor system. It has been observed that the results are more reliable and reproducible.