MOCVD制备过掺杂GaN基稀磁半导体微结构研究

应用MOCVD方法我们在c轴取向的蓝宝石衬底上生长出Fe掺杂和Mn掺杂GaN薄膜。通过改变前驱物的通入量，我们制备出不同掺杂浓度的样品。应用高分辨透射电镜，我们对样品的微结构进行了分析。对于Fe过掺杂GaN样品，我们发现了六角结构的Fe3N团簇的存在，并且Fe3N(0002)面平行于GaN(0002)面；对于Mn过掺杂GaN样品，我们发现了六角结构的Mn6N2.58相的存在，并且Mn6N2.58(0002)面平行于GaN(0002)面。同时，由于晶格中掺入了大量掺杂离子，GaN晶格取向遭到了破坏，导致了部分GaN(0002)面的倾斜。磁学测量表明均一相的Fe掺杂GaN显现铁磁性，而均一相Mn掺杂GaN没有铁磁性。由于铁磁性Fe单晶和Fe3N团簇的存在，相比于均一性Fe掺杂GaN，过掺杂GaN样品的磁性大幅度增强，而Mn过掺杂GaN样品显现出很弱的铁磁性，这有可能来源于Mn6N2.58相。

Microstructural properties of over-doped GaN-based diluted magnetic semiconductors grown by MOCVD

We have grown transition metal (Fe, Mn) doped GaN thin films on c-oriented sapphires by metal organic chemical vapor deposition (MOCVD). By varying flow of metal precursor, series of samples with different ion concentration are synthesized. Microstructural properties are characterized by high-resolution transmission electron microscope (HRTEM). For Fe over-doped GaN samples, hexagonal Fe₃N clusters are observed with Fe₃N(0002) parallel to GaN(0002) while for Mn over-doped GaN, hexagonal Mn₆N_2.58 phase are observed with Mn₆N_2.58(0002) parallel to GaN(0002). Meantime, with higher concentration ions doping into the lattice matrix, the partial lattice orientation is distorted, leading to the tilt of GaN (0002) planes. Magnetic measurement show that the homogeneous Fe doped GaN samples are ferromagnetic and Mn doped GaN are not ferromagnetic. The magnetization of Fe over-doped GaN sample promotes a lot which is ascribed to the participation of ferromagnetic iron and Fe₃N while Mn over-doped sample show very weak ferromagnetic behavior which may probably originate from Mn₆N_2.58.