Dresden 2011 – wissenschaftliches Programm

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MA: Fachverband Magnetismus

MA 63: Poster II (Surface Magnetism/ Magnetic Imaging/ Topological Insulators/ Spin Structures and Magnetic Phase Transitions/ Graphene/ Magnetic Thin Films/ Magnetic Semiconductors/ Magnetic Half-metals and Oxides/ Spin-dependent Transport/ Spin Excitations and Spin Torque/ Spin Injection and Spin Currents in Heterostructures/ Spintronics/ Magnetic Storage and Applications)

MA 63.89: Poster

Freitag, 18. März 2011, 11:00–14:00, P2

Modification of the interface in Co₂FeSi/(Al,Ga)As hybrid structures by insertion of ZnO barriers — •Yori Manzke, Rouin Farshchi, Abbes Tahraoui, Jens Herfort, and Manfred Ramsteiner — Paul-Drude-Institut Berlin, Hausvogteiplatz 5-7, 10117 Berlin, Germany

Thin ZnO layers of various thicknesses at the hybrid interface of Co₂FeSi/(Al,Ga)As spin light-emitting diodes (spin-LEDs) are being investigated, particularly regarding their usability as diffusion barriers for Co and Fe atoms, which have previously been found to strongly deteriorate the semiconductor (SC) material. The insertion of the ZnO layers is found to drastically alter the ferromagnetic injector layer properties, leading to a decrease in the saturation magnetization as well as a drastic increase in sheet resistance. Both of these findings indicate a strong intermixing of ZnO and Co₂FeSi. Consequently, electroluminescence from the LEDs containing ZnO is only observed close to contact rings, as opposed to the homogeneous emission over the entire LED mesa area observed for a reference sample prepared without any oxide layer. The diffusion of Co and Fe atoms which takes place during Co₂FeSi growth at 280 ^∘C was studied by secondary ion mass spectrometry. Only thicker ZnO barriers were found to act as efficient diffusion barriers, while very thin ZnO layers even lead to an increase of the Co and Fe concentrations in the SC. From these findings it is concluded that ZnO appears not to be promising for the use as a barrier layer in ferromagnet/SC spin injection devices.