15 September 2011 Defect induced Raman active modes in Mn doped ZnO thin films
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Zinc oxide is a II-VI semiconductor with a wide direct band gap of about 3.37 eV at room temperature. Among the various growth techniques of 'Mn' doped ZnO thin films, pulsed laser deposition (PLD) offers the advantages such as deposition at relatively high oxygen pressure, high deposition rate and growth of highly oriented crystalline films at low substrate temperature. The substitution of 'Mn' in ZnO host lattice affects the lattice dynamics. Raman scattering provides a great deal of information in the optical modes of vibrations at the center of Brillouin zone. The parameters of Raman mode such as frequency, line width and lifetime provide the basic information of lattice dynamics. The PLD grown films were analysed using x-ray diffraction (XRD), scanning electron microscopy (SEM), UV-Vis-NIR spectroscopy and Raman spectroscopy. Good optical quality of the films was confirmed from the transmittance of the film greater than 80% in the visible region. The presence of non-polar E2high and E2low Raman modes in thin films indicates that 'Mn' doping didn't change the wurtzite structure of ZnO. The intensity of E2high mode and the peak position shifted towards the lower frequency with increase of 'Mn' concentration. Apart from the normal modes of ZnO the Zn1-xMnxO ceramic targets shows two additional modes at 332 cm-1 (I2) and 524 cm-1 (I4). The modes I2 and I4 are assigned as multi-phonon scattering considering the two phonon process in the disordered lattice due to Mn doping.
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Arun Aravind, Arun Aravind, K. Hasna, K. Hasna, M. K. Jayaraj, M. K. Jayaraj, } "Defect induced Raman active modes in Mn doped ZnO thin films", Proc. SPIE 8100, Spintronics IV, 81001L (15 September 2011); doi: 10.1117/12.893266; https://doi.org/10.1117/12.893266

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