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

Zni(1-x)Mn(x)O 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 Zn(1-x)Nn(x)O ceramic targets show two additional modes at 332 cm(-1) (I-1) and 524 cm(-1) (I-2). The broad Raman peaks (340-600 cm(-1)) observed Zn-0.90 Mn0.10O thin films can be deconvoluted into five peaks, denoted as P-1-P-5. 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-2(1)low, B-1(hilgh) 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 0.42 mu B/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. (C) 2012 Elsevier B.V. All rights reserved.