Ferromagnetic GaN by focussed ion beam implanted rare earths

半导体自旋电子学是一个被广泛研究的研究领域[1-3]，在许多子领域已经取得了重大进展。另一方面，许多挑战仍然存在，特别是寻找有效的电自旋注入材料的任务。在这里，关于gd掺杂GaN的室温铁磁性的报道[4-6]刺激了世界上几个小组的深入研究。尽管进行了大量的研究，但关于钆掺杂氮化镓的磁性仍存在许多悬而未决的问题，文献中也存在一些争论。在项目的当前阶段，我们在磁输运实验中检测到Gd的特征，但无法记录迟滞行为作为铁磁性的明确证明。提出的项目的主要重点将是澄清GaN掺杂Gd成为铁磁性的条件。在MBE中注入Ga和Ar将有助于阐明缺陷对磁性能的影响。我们将从各种来源，特别是MBE（含O）和MOVCD（含H）生长的材料中植入Gd，以解决不同杂质原子存在的影响。此外，在植入后退火的变化，应深入了解缺陷和杂质原子的作用。在磁输运测量中，我们将通过与未植入的参考样品和未植入的参考样品进行比较，将Gd诱导磁化的影响与纯缺陷相关的特征分开。

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.