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 E2high and E2low 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 B1low, B1low2, B1high and A1LO 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.

► Defect induced Raman active modes in Mn doped ZnO thin films.
► Room temperature ferromagnetism.
► Morphological variations of ZnO thin films with Mn doping.
► Variation of refractive index of ZnO thin films with Mn doping.