Structure, optical, and magnetic properties of Mn-doped ZnO films prepared by sputtering

Abstract

The microstructural, optical, and magnetic properties and room-temperature photoluminescence (PL) of Mn-doped ZnO thin films were studied. The chemical compositions were examined by energy dispersive X-ray spectroscopy (EDS) and the charge state of Mn ions in the ZnO:Mn films was characterized by X-ray photoelectronic spectrometry (XPS). From the X-ray diffraction (XRD) data of the samples, it can be found that Mn doping does not change the orientation of ZnO thin films. All the films prepared have a wurtzite structure and grow mainly along the c-axis orientation. The grain size and the residual stress were calculated from the XRD results. The optical transmittance of the film decreases with the increase of manganese content in ZnO. The room-temperature photoluminescence of the films shows that the intensity of near band energy (NBE) emission depends strongly on the Mn content. The hysteresis behavior indicates that the films with the Mn content below 9at% are ferromagnetic at room temperature.

Keywords

ZnO / magnetron sputtering / ferromagnetism / optical properties / photoluminescence

References

[1] Furdyna J.K. Diluted magnetic semiconductors. J. Appl. Phys., 1988, 64(4): R29.

[2] Munekata H., Ohno H., Von Molnár S., et al. Diluted magnetic III-V semiconductors. Phys. Rev. Lett., 1989, 63(17): 1849.

[3] Dietl T., Ohno H., Matsukura F., Cibert J., Ferrand D. Zener model description of ferromagnetism in zinc-blende magnetic semiconductors. Science, 2000, 287(12): 1019.

[4] Ren L.L., Won Y.J. Effects of temperature and nickel content on magnetic properties of Ni-doped ZnO. Rare Met., 2006, 25(Suppl.2): 24.

[5] Xia H.P., Wang J.H., Wang H.Y., et al. Optical spectroscopy and crystal-field strength of Cr³⁺ in various solid matrixes. Rare Met., 2006, 25(1): 51.

[6] Yu M., Liu J.H., Li S.M. Fabrication and characterization of highly ordered Ni_0.5Zn_0.5Fe₂O₄ nanowire/tube arrays by sol-gel template method. J. Univ. Sci. Technol. Beijing, 2007, 14(5): 469.

[7] Chang Y.Q., Wang D.B., Luo X.H., et al. Synthesis, optical, and magnetic properties of diluted magnetic semiconductor Zn_1−xMn_xO nanowires via vapor phase growth. Appl. Phys. Lett., 2002, 83(19): 4020.

[8] Norton D.P., Pearton S.J., Hebard A.F., et al. Ferromagnetism in Mn-implanted ZnO:Sn single crystals. Appl. Phys. Lett., 2003, 82(2): 239.

[9] A.K. Pradha, K. Zhang, S. Mohanty, et al., High-temperature ferromagnetism in pulsed-laser deposited epitaxial (Zn,Mn)O thin films: Effects of substrate temperature, Appl. Phys. Lett., 86(2005), No.15, art. No.152511.

[10] Kundaliya D.C., Ogale S.B., Lofland S.E., et al. On the origin of high-temperature ferromagnetism in the low-temperature-processed Mn-Zn-O system. Nat. Mater., 2004, 3, 709.

[11] Han S.J., Jang T.H., Kim Y.B., et al. Magnetism in Mn-doped ZnO bulk samples prepared by solid state reaction. Appl. Phys. Lett., 2003, 83(5): 920.

[12] Zheng R.K., Liu H., Zhang X.X., Roy V.A.L., Djurišiæ A.B. Exchange bias and the origin of magnetism in Mn-doped ZnO tetrapods. Appl. Phys. Lett., 2001, 85(13): 2589.

[13] Kim S.S., Moon J.H., Lee B.T., Song O.S., Je J.H. Heteroepitaxial growth behavior of Mn-doped ZnO thin films on Al₂O₃ (0001) by pulsed laser deposition. J. Appl. Phys., 2004, 95(2): 454.

[14] Fukumura T., Jin Z.W., Kawasaki M., et al. Magnetic properties of Mn-doped ZnO. Appl. Phys. Lett., 2001, 78(7): 958.

[15] Moulder J.F., Stickle W.F., Sobol P.E., Bomben K.D. Handbook of X-ray Photoelectron Spectroscopy, 1995 Eden Prairie, Physical Electronics Inc., 235.

[16] Fujimura N., Nishihara T., Goto S., Xu J., Ito T. Control of preferred orientation for ZnO_x films: control of self-texture. J. Cryst. Growth, 1993, 130(1–2): 269.

[17] Weller M.T. Inorganic Materials Chemistry, 1997 Oxford, Oxford University Press, 153.

[18] Wang Y.G., Lau S.P., Lee H.W., et al. Comprehensive study of ZnO films prepared by filtered cathodic vacuum arc at room temperature. J. Appl. Phys., 2003, 94(3): 1597.

[19] Hopfield J.J., Thomas D.G. Fine structure and magneto-optic effects in the exciton spectrum of cadmium sulfide. Phys. Rev., 1961, 122(1): 35.

[20] Reynolds D.C., Look D.C., Jobai B., et al. Neutral-donor-bound-exciton complexes in ZnO crystals. Phys. Rev. B, 1998, 57(19): 12151.

[21] Kim Y.S., Lee S.H., Im J.I., Chung Y.C. Magnetic properties and electronic structure of transition metal adsorbed polar-ZnO surfaces: Ab initio calculations. Jpn. J. Appl. Phys. Part 1, 2007, 46(9B): 6312.