In this paper we investigate the incorporation of hydrogen in Ga1−xMnxAs for samples with x ⬇ 0.005 grown by metal-organic vapor-phase epitaxy and with 0.03⬍ x ⬍ 0.05 grown by low-temperature molecular-beam epitaxy. The anisotropic electron-paramagnetic-resonance 共EPR兲 signal observed for the paramagnetic Ga1−xMnxAs samples with x ⬇ 0.005 after hydrogenation is characteristic for Mn2+ 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 MnGa-As atom pair upon hydrogenation ⌬VH / VMn-As ⬇ 0.14⫾ 0.07 as deduced from a comparison of the high-resolution x-ray diffraction 2⌰ / ⍀ scans of as-grown and hydrogenated samples with 0.03⬍ x ⬍ 0.05 is expected for Mn-H complex formation. How- ever, 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 共EXAFS兲 analysis and x-ray ab- sorption near-edge spectroscopy 共XANES兲 on samples with 0.03⬍ x ⬍ 0.05 show no indication for bond- centered 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 Ga1−xMnxAs 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.
Local structure of Mn in hydrogenated Ga1-xMnxAs
Filippone, F.;Amore Bonapasta, A.;
2008
Abstract
In this paper we investigate the incorporation of hydrogen in Ga1−xMnxAs for samples with x ⬇ 0.005 grown by metal-organic vapor-phase epitaxy and with 0.03⬍ x ⬍ 0.05 grown by low-temperature molecular-beam epitaxy. The anisotropic electron-paramagnetic-resonance 共EPR兲 signal observed for the paramagnetic Ga1−xMnxAs samples with x ⬇ 0.005 after hydrogenation is characteristic for Mn2+ 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 MnGa-As atom pair upon hydrogenation ⌬VH / VMn-As ⬇ 0.14⫾ 0.07 as deduced from a comparison of the high-resolution x-ray diffraction 2⌰ / ⍀ scans of as-grown and hydrogenated samples with 0.03⬍ x ⬍ 0.05 is expected for Mn-H complex formation. How- ever, 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 共EXAFS兲 analysis and x-ray ab- sorption near-edge spectroscopy 共XANES兲 on samples with 0.03⬍ x ⬍ 0.05 show no indication for bond- centered 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 Ga1−xMnxAs 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.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
