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

稀磁半导体被认为是实现半导体异质结构中自旋注入或自旋对准的潜在候选材料。我们最近发现掺钆的氮化镓在室温下显示铁磁性。这种磁性排序的原子机制尚未完全理解，尽管理论上的考虑已经预测了稀磁性宽禁带半导体的高居里温度值。该项目将涉及通过分子束外延（MBE）生长铁磁gd掺杂族iii氮化物以及结构-性能关系的研究。与包含小簇第二相的颗粒材料相比，主要关注的是稀磁半导体的实现。由于氮化外延薄膜是高度缺陷的，我们将通过使用不同的衬底材料来详细研究晶体完美性对MBE磁性能的影响。此外，利用反映高电阻率的gd掺杂GaN和AlN层来研究与Si和Mg共掺杂的潜力，以实现n型和p型电导率及其对磁性行为的影响。

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.