An insight to origin of ferromagnetism in ZnO and N implanted ZnO thin films: Experimental and DFT approach

Abstract

In the present study, we have elucidated an effective way to simultaneously tune the optical bandgap and magnetic properties of zinc oxide (ZnO) thin films. This can be achieved by the incorporation of nitrogen ions in the host matrix. We have systematically investigated the influence of N ions in ZnO thin films through experimental techniques and the density functional theory (DFT) calculations to understand the physical mechanism governing the observed magnetic behaviour and the variation in bandgap. For this, RF sputtered ZnO thin films deposited over Si substrates were implanted with N ions by varying the fluences and studied for their optical and magnetic properties. The pristine ZnO film is having saturation magnetization of ∼2.45 emu/cm3 which becomes almost twice for the ion fluence of 1 × 1017 ions/cm2. Furthermore, the optical bandgap is tuned from 3.27 eV to 3.04 eV with N ion implantations. This study provides a new insight to understand the basis of ferromagnetism in non-magnetic ions doped ZnO system.