Ferromagnetic GaN by focussed ion beam implanted rare earths

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Semiconductor spintronic was and is an intensively studied research field [1-3] and in many sub-areas significant progress has been made. On the other hand, many challenges remain, especially the task to find a material for effective electrical spin-injection. Here the report of room temperature ferromagnetism in Gd-doped GaN [4-6] spurred intensive research efforts by several groups worldwide. Despite intensive efforts, many open questions remain concerning the magnetic properties Gd-doped GaN and there is some debate in literature. In the current phase of the project, we detected signatures of the Gd in magnetotransport experiments but could not record hysteretic behaviour as clear prove of ferromagnetism. The main focus in the proposed project will be on clarifying the conditions under which GaN doped with Gd becomes ferromagnetic. The implantation of Ga and Ar into MBE Gd-doped GaN will help to clarify the role of defects for the magnetic properties. We will implant Gd into GaN from various sources, especially MBE (contains O) and MOVCD (contains H) grown material, to address the influence of the different impurity atoms present. Also the changes upon post-implantation annealing should give insight in the role defects and impurity atoms. In magnetotransport measurements we will separate the effects due to the Gd induced magnetization from the pure defect related features by comparing not only to unimplanted but also to non-rare-earth implanted reference samples.