Micro-x-ray absorption near-edge structure imaging for detecting metallic Mn in GaN

In this study, we report the application of a synchrotron radiation microprobe to the analysis of Mn valencies in GaN. X-ray absorption near-edge structure (XANES) images taken around MnK-edge in fluorescence detection mode reveal the concentration of oxidation states of Mn centers. By fitting the XANES curve for each point of the image, the distributions of the Mn0, Mn2+, and Mn3+ oxidation states are obtained. At low Mn concentrations, there is a homogeneous mixture of Mn2+ and Mn3+ centers, while at high Mn content strong spatial-dependent Mn0 and Mn2+ distributions characterize the XANES maps. In a supplementary way with respect to Mn2+, the Mn0 pattern suggests the presence of specific cluster-like features, indicating surface segregation of metallic Mn centers.

[1]  Christoph Rau,et al.  Microimaging and tomography with chemical speciation , 2003 .

[2]  D. Awschalom,et al.  Submicron GaMn quasicrystals in ferromagnetic GaAs , 1997 .

[3]  W. Richter,et al.  Molecular Beam Epitaxy , 1989 .

[4]  Observation of sphere resonance peak in ferromagnetic GaN:Mn , 2003 .

[5]  K. Ando,et al.  Magneto-optical studies of s,p–d exchange interactions in GaN:Mn with room-temperature ferromagnetism , 2003 .

[6]  H. Ohno,et al.  Hole-mediated ferromagnetism in tetrahedrally coordinated semiconductors , 2000, cond-mat/0007190.

[7]  M. Willander,et al.  III–nitrides: Growth, characterization, and properties , 2000 .

[8]  Masaaki Tanaka,et al.  Mn impurity in Ga 1 − x Mn x As epilayers , 1999 .

[9]  Martin Eickhoff,et al.  Mn-rich clusters in GaN: Hexagonal or cubic symmetry? , 2005 .

[10]  Molecular beam epitaxial growth of GaN and GaMnN using a single precursor , 2004 .

[11]  M. Kamińska,et al.  Magnetic and optical properties of GaMnN magnetic semiconductor , 2001 .

[12]  S. Bajt,et al.  Synchrotron x‐ray fluorescence microprobe: Quantification and mapping of mixed valence state samples using micro‐XANES , 1995 .

[13]  Oliver Ambacher,et al.  The Mn3+/2+ acceptor level in group III nitrides , 2002 .

[14]  M. Stutzmann,et al.  Direct Observation of Mn Clusters in GaN by X-ray Scanning Microscopy , 2004 .

[15]  H. Ohno,et al.  Making nonmagnetic semiconductors ferromagnetic , 1998, Science.

[16]  A. Simionovici,et al.  ID22: a multitechnique hard X-ray microprobe beamline at the European Synchrotron Radiation Facility. , 2005, Journal of synchrotron radiation.

[17]  H. Ohno,et al.  Zener model description of ferromagnetism in zinc-blende magnetic semiconductors , 2000, Science.

[18]  J. Philipp,et al.  Growth and characterization of GaN:Mn epitaxial films , 2003 .

[19]  H. Ohno,et al.  Growth and properties of (Ga,Mn)As films with high Mn concentration , 2001 .

[20]  H. Mariette,et al.  Strong influence of Ga/N flux ratio on Mn incorporation into Ga1−xMnxN epilayers grown by plasma-assisted molecular beam epitaxy , 2003 .

[21]  David P. Norton,et al.  Wide band gap ferromagnetic semiconductors and oxides , 2003 .