Local structure of Mn in hydrogenatedGa1−xMnxAs

Abstract

In this paper we investigate the incorporation of hydrogen in Ga 1−x Mn x As for samples with x Ϸ 0.005 grown by metal-organic vapor-phase epitaxy and with 0.03Ͻ x Ͻ 0.05 grown by low-temperature molecular-beam epitaxy. The anisotropic electron-paramagnetic-resonance ͑EPR͒ signal observed for the paramagnetic Ga 1−x Mn x As samples with x Ϸ 0.005 after hydrogenation is characteristic for Mn 2+ substitutional on the Ga site. Contributions of crystal fields to the EPR signal indicative of Mn-H complexes with H atoms near the Mn are negligibly small. The relative volume increase in a single Mn Ga -As atom pair upon hydrogenation ⌬V H / V Mn-As Ϸ 0.14Ϯ 0.07 as deduced from a comparison of the high-resolution x-ray diffraction 2⌰ / ⍀ scans of as-grown and hydrogenated samples with 0.03Ͻ x Ͻ 0.05 is expected for Mn-H complex formation. However, the accuracy of this measurement is not sufficient to draw unambiguous conclusions about the specific nature of the Mn-H configuration. Extended x-ray absorption fine-structure ͑EXAFS͒ analysis and x-ray absorption near-edge spectroscopy ͑XANES͒ on samples with 0.03Ͻ x Ͻ 0.05 show no indication for bondcentered Mn-H complexes as determined from a detailed comparison of the EXAFS Fourier transforms and the XANES spectra with the simulations. The overwhelming structural evidence of these techniques therefore points to comparatively large distances between the Mn and the H atoms at least in Ga 1−x Mn x As films with Mn concentrations above 0.005, which would be the case for either complexes with the hydrogen atom in the antibonding position or for compensation via isolated interstitial hydrogen.

Complexes and Clusters

“…5.4d). We refer to the same paper [33] for an explication of how Mn K-edge XANES, coupled to FMS simulations performed following the same strategy as in the previous section, confirms the EXAFS result. In summary, XAS supports the hypothesis of Mn-H ab as the majority complex at relatively high Mn incorporation, despite the theoretical prediction of the Mn-H bc one.…”

“…c Expected radial distribution function for the Mn-H bc configuration and d for the Mn-H ab one. (Reprinted with permission from [33]. Copyright 2008 by the American Physical Society.…”

“…Electron paramagnetic resonance (EPR), which is sensitive to the symmetry of the field of the Mn 2+ atoms (from which information on the position of the H may be inferred), rather suggested the Mn-H ab configuration [33]; however this technique only works at the dilute limit and cannot be used to study samples with Mn concentration equal to some percent since the spectra broaden due to the interaction of neighboring Mn 2+ centers. 1 Bihler et al addressed the issue of Mn-H complexes in hydrogenated Ga 1−x Mn x As by Mn K-edge XAS [33]. Measurements were performed at the BM29 beamline of the European Synchrotron Radiation Facility (ESRF) in fluorescence mode on 0.03 < x < 0.05 epilayers grown by low-temperature MBE [34].…”

Local structure of indium in quinary (InGa)(AsSbN)/GaAs quantum wells

“…25͒ and Mn-H complexes in Ga 1−x Mn x As. 26 In the present work, we used In K-edge XAFS to study the local structure around In atoms in quinary ͑InGa͒͑AsSbN͒ QWs, materials of particular importance for the manufactory of laser devices working near the second minimum of attenuation in optical fiber ͑1.55 m͒, 27 and possible atomic-dimensional structural changes during thermal annealing with different durations.…”

Local structures and concentration dependence of magnetic properties in Cr- and Mn-doped amorphous silicon ferromagnetic thin films

“…It is reported in previous EXAFS literature that hydrogenation can reduce the disorder and distortion either intrinsic or induced by incorporation of impurities in semiconductor materials. [14][15][16][17] Samples of Mn-and Cr-doped amorphous silicon ͑a-Si͒ thin films of thickness 200 nm were deposited by rf magnetron cosputtering technique at room temperature on glass and Si substrates. To eliminate the dangling bonds which can trap dopants/carriers and therefore degrade the electronic and magnetic properties, these films were hydrogenated using a sputtering gas mixture of 20% H 2 in Ar during the growth.…”