Structural, optical and magnetic properties of Mn doped ZnO thin films prepared by pulsed laser deposition

Zn1−xMnxO thin films were grown by pulsed laser deposition. The phase purity and the structure were confirmed by X-ray diffraction studies. The films have a transmittance more than 80% in the visible region. The refractive index of Zn0.90Mn0.10O films is found to be 1.77 at 550 nm. The presence of non-polar E 2 high and E 2 low Raman modes in thin films indicates that ‘Mn’ doping does not change the wurtzite structure of ZnO. Apart from the normal modes of ZnO the Zn1−xMnxO ceramic targets show two additional modes at 332 cm−1 (I1) and 524 cm−1 (I2). The broad Raman peaks (340–600 cm−1) observed Zn0.90Mn0.10O thin films can be deconvoluted into five peaks, denoted as P1–P5. The possible origins of Raman peaks in Zn1−xMnxO films are the structural disorder and morphological change caused by the Mn dopant. The B 1 low , B 1 low 2 , B 1 high and A 1 LO modes as well as the surface phonon mode have been observed in heavily Mn-doped ZnO films. Zn0.98Mn0.02O thin film shows room temperature ferromagnetism. The saturation magnetic moment of the Zn0.98Mn0.02O thin film is 0.42μB/Mn atom. The undoped ZnO film prepared under the same condition shows diamagnetic nature. At higher doping concentrations the formation of Mn clusters suppress the room temperature ferromagnetism in Zn1−xMnxO thin films and shows paramagnetism. XPS confirms the incorporation of Mn2+ into the ZnO lattice.