Soft X-ray Emission Spectra of Mn-doped ZnO Thin Films

doi:10.3724/SP.J.1077.2012.00296

Abstract

Abstract: The local electronic structures of Zn_0.97Mn_0.03O和Zn_0.67Mn_0.33O thin films prepared by a molecular beam epitaxy (MBE) at 200℃ were investigated by soft X-ray fluorescence spectrometer of beamline 8.0.1 of the Advanced Light Source (ALS). The special interest can be given to find the relationship between the electronic structure of Mn and magnetic properties of our samples. Analysis of the integral intensity ratio of Mn L₂to L₃emission lines (I(L₂)/I(L₃)) from resonant and nonresonant Mn L_2,3 X-ray emission spectra (XES) indicates that ferromagnetism (FM) is related to the free d charge carriers in the film. For ferromagnetic Zn_0.97Mn_0.03O sample, the majority of Mn atoms are incorporated at Zn substitutional sites and the film shows strong Coster-Kronig (C-K) transitions due to a large amount of free charge carriers available around Mn atoms. Both non-localized d charge carriers as itinerant electrons and 4s electrons from interstitial Mn obtained by Ruderman-Kittel-Kasuya-Yosid (RKKY) calculations can induce the ferromagnetic exchange interaction. However, the disappearance of FM in Zn_0.67Mn_0.33O sample can be explained in terms of the existence of MnO clusters leading to a reduction in the number of free charge carriers.

Key words: ZnO, X-ray emission spectra, C-K transition, free d carriers

CLC Number:

O484

JIN Jing, ZHANG Xin-Yi, ZHOU Ying-Xue. Soft X-ray Emission Spectra of Mn-doped ZnO Thin Films[J]. Journal of Inorganic Materials, 2012, 27(3): 296-300.

References

[1] Das Sarma S. A new class of device based on electron spin, rather than on charge, may yield dthe next generation of microelectronics. Am. Sci., 2001, 89(6): 516-523.

[2] Bratkovsky A M. Spintronic effects in metallic, semiconductor, metal-oxide and metal-semiconductor heterostructures. Rep. Prog. Phys., 2008, 71(2): 026502.

[3] Manyala N, DiTusa J F, Aeppli G, et al. Doping a semiconductor to created an unconventional metal. Nature, 2008, 454: 976-980.

[4] Thakur P, Gautam S, Chae K H, et al. X-ray absorption and emission studies of Mn-doped ZnO thin films. Journal of the Korean Physical Society, 2009, 55(1): 177-182.

[5] Singhal R K, Dhawan M S, Gaur S K, et al. Room temperature ferromagnetism in Mn-doped dilute ZnO semiconductor: an electronic structure study using X-ray photoemission. J. Alloys Compd., 2009, 477(1/2): 379-385.

[6] Kolesnik S, Dabrowski B. Absence of room temperature ferromagnetism in bulk Mn-doped ZnO. J. Appl. Phys., 2004, 96(9): 5379-5381.

[7] Zhang J, Skomski R, Sellmyer D J. Sample preparation and annealing effects on the ferromagnetism in Mn-doped ZnO. J. Appl. Phys., 2005, 97(10): 10D303-1-3.

[8] Wu Y, Rao K V, Wolfgang Voit, et al. Room temperature ferromagnetism and fast ultraviolet photoresponse of inkjet-printed Mn-doped ZnO thin films. IEEE Trans. Magn., 2010, 46(6): 2152-2155.

[9] Jin J, Chang G S, Boukhvalov D W, et al. Element-specific electronic structure of Mn dopants and ferromagnetism of (Zn,Mn)O thin films. Thin Solid Films, 2010, 518(10): 2825-2829.

[10] Xu W, Zhou Y X, Zhang X Y, et al. Local structures of Mn in dilute magnetic semiconductor ZnMnO. Solid State Commun., 2007, 141(7): 374-377.

[11] Chang G S, Kurmaev E Z, Boukhvalov D W, et al. Clustering of impurity atoms in Co-doped anatase TiO2 thin films probed with soft x-ray fluorescence. J. Phys: Condens. Matter, 2006, 18(17): 4243-4251.

[12] Fromme B, Brunokowski U, Kisker E, et al. d-d excitations and interband transitions in MnO: A spin-polarized electron- energy-loss study. Phys. Rev. B, 1998, 58(15): 9783-9792.

[13] Butorin S M, Guo J H, Magnuson M, et al. Low-energy d-d excitations in MnO studied by resonant X-ray fluorescence spectroscopy. Phys. Rev. B, 1996, 54(7): 4405-4408.

[14] Bartkowski S, Neumann M, Kurmaev E Z, et al. Electronic sturcture of titanium monoxide. Phys. Rev. B, 1997, 56(16): 10656-10667.

[15] Kurmaev E Z, Ankudinov A L, Rehr J J, et al. The L2:L3 intensity ratio in soft X-ray emission spectra of 3d-metals. J. Electr. Spectr. Relat. Phenom., 2005, 148(1): 1-4.

[16] Grebennikov V I. Surface Investigations: X-ray, Synchrotron and Neutron Techniques 11. 2002: 41.