Raman scattering and photoluminescence investigations of N doped ZnO thin films: Local vibrational modes and induced ferromagnetism

N doped ZnO (ZnO:N) thin films are prepared by pulsed laser deposition in an oxygen environment using ZnO:N targets with varying nitrogen doping concentrations (1%–10%). The impact of nitrogen incorporation on the microstructural properties of prepared ZnO:N thin films has been studied using Raman scattering. The Raman shift of E2(high) mode towards lower frequencies indicate the substitution of N at O lattice sites (NO). A local vibrational mode corresponding to Zn–N was observed at 480.3 cm−1 in N doped ZnO thin films and highlights the increased strength of the Zn–N bond in the ZnO lattice. Photoluminescence studies reveal the dominant near band edge emission peak in the ultraviolet region and the absence of deep level emission due to defects. The ZnO:N thin films are found to possess room temperature ferromagnetism. N is found to play a significant role in arising ferromagnetism in ZnO and possess a solubility limit of 8% for uniform and homogeneous atomic substitution in ZnO. The present study confirms the promising application of N doped ZnO (ZnO:N) thin films for room temperature spintronics applications.