Molecular-beam epitaxy of group III nitride-based dilute magnetic semiconductors

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Dilute magnetic semiconductors are considered as potential candidates for realizing spininjection or spin-alignment in semiconductor heterostructures. We have recently found that Gd-doped GaN shows ferromagnetism at room temperature. The atomistic mechanism for this magnetic ordering is not yet completely understood, although theoretical considerations have predicted high Curie temperatures values in dilute magnetic wide bandgap semiconductors. The project will deals with the growth of ferromagnetic Gd-doped group-III nitrides by molecular beam epitaxy (MBE) and the study of the structure-property relation. A main focus is on the realization of dilute magnetic semiconductors in comparison to granular materials that include small clusters of second-phases. Because epitaxial nitride films are highly defective, we will in detail investigate the effect of the crystalline perfection on the magnetic properties by using different substrate materials for the MBE. Furthermore, Gd-doped GaN and AlN layers reflecting high electric resistivity are used to investigate the potential of codoping with Si and Mg in order to realize n- and p-type conductivity and the effect on the magnetic behaviour.