Regensburg 2007 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 7: III-V semiconductors I

HL 7.3: Vortrag

Montag, 26. März 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 T_S=775^∘C down to T_S=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 T_S 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 T_S 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 T_S 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.