Structural, optical and magnetic properties of highly oriented transition metal (Mn/Co/Ni/Cu) doped ZnO thin films prepared by PLD

摘要

ZnO doped with transition metal (TM) thin films were grown by pulsed laser deposition. XRD pattern reveals that all the ZnTMO films have c-axis orientation normal to the substrate. The reciprocal space mapping shows that the crystallinity of ZnTMO film deteriorates at higher doping of TM. All the TM doped ZnO films have transmittance greater than 75% in the visible region. The band gap of the ZnTMO thin films shows red shift on doping with Ni and Cu where as blue shift is observed for Co and Mn which increases with TM concentration. The copper doped ZnO thin film shows green PL emission at 542 nm along with the band edge emission at 385 nm. But other TM doping shows only band edge emission (385nm) and its intensity decreases at higher doping percentage. The presence of non-polar E_2~(high) and E_2~(low) Raman modes in thin films indicates that 'TM' doping do not alter the wurtzite structure of ZnO. The magnetic studies of the TM doped ZnO shows room temperature ferromagnetism.