Complexes formed by H and Mn interstitials (Mnint) in MnxGa1−xAs dilute magnetic semiconductors were investigated by using first-principles density functional theory methods in both gradient corrected spin density and Hubbard U approximations. In agreement with previous results for complexes of H with substitutional Mn (MnGa), the present results confirmed the importance of electron correlation effects, as the Hubbard U treatment weakened the H–Mn bonds even in the H–Mnint complexes. They also indicated that H compensated (without passivating) the Mnint by forming Mnint–H donor–acceptor (D–A) pairs, and then Mnint–H complexes. In the H–Mnint and H–MnGa complexes, the H–Mn D–A interaction was always mediated by a host atom, thus leading to the formation of H–Ga bonds for interstitial Mn and of H–As bonds for substitutional Mn. This implied quite different H vibrational frequencies for the H–Mnint and H–MnGa complexes, thus suggesting that H could be used as a probe for discriminating, between the two Mn forms, via vibrational spectroscopy measurements. Finally, a higher stability of the H–Mnint with respect to the H–MnGa complexes was found, which suggested the use of hydrogenation procedures to control the effects of Mnint upon the MnxGa1−xAs properties.

Hydrogen and Interstitial Mn Complexes in MnxGa1-xAs Dilute Magnetic Semiconductors. F.Filippone, G.Mattioli, A.A.Bonapasta: Journal of Physics - Condensed Matter, 2008, 20[12], 125215 (10pp)