Regensburg 2007 – scientific programme
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HL: Fachverband Halbleiterphysik
HL 7: III-V semiconductors I
HL 7.3: Talk
Monday, March 26, 2007, 11:30–11:45, H17
Spinoidal decomposition in GaN:Mn grown by MBE — •Dong-Du Mai, Tore Niermann, Martin Roever, Jan Zenneck, Henning Schuhmann, Amilcar Bedoya Pinto, Joerg Malindretos, Michael Seibt, and Angela Rizzi — IV. Physikalisches Institut and Virtual Institute for Spin Electronics (VISel), Georg-August Universität Göttingen, D-37077 Göttingen, Germany
GaN:Mn is grown by plasma assisted Molecular Beam Epitaxy (MBE) on GaN/Al2O3(0001). Samples were grown at various substrate temperatures, from TS=775∘C down to TS=575∘C and at various metal-to-nitrogen fluxes. It was possible to define parameter regions in which wurtzite GaMnN grows without second phases. For growth at high TS and close to stoichiometry GaN:Mn exhibits good crystallinity (TEM, XRD). However only a maximum of ∼ 1% incorporation of diluted Mn can be achieved. At lower TS and nitrogen-rich growth regime higher manganese incorporation (up to ∼ 5%) is possible without second phase formation. However the crystal quality worsens. EDX maps measured both in cross-section and plane-view through a scanning TEM analysis reveal an inhomogeneous distribution of the Mn in the layers (spinoidal decomposition). SQUID measurements are discussed in correlation with the structural and compositional analysis.
At regular TS PL measurements near the band edge show strong bound and free excitonic luminescence (3 meV FWHM). Also a characteristic intra-3d luminescence for substitutional Mn at 1.42 eV (ZPL) could be detected. The latter is quenched at increasing Mn incorporation and its intensity correlates with the near band edge PL.