论文部分内容阅读
采用分子束外延技术分别在不同晶面的蓝宝石(sapphire Al2O3)基片上制备了沿c轴生长的Zn0.96Co0.04O稀磁半导体薄膜.发现在Al2O3(1120)晶面(a面)上薄膜是二维层状外延生长的高质量单晶薄膜,而在Al2O3(0001)晶面(c面)上薄膜却具有有趣的孪晶结构,部分区域相互之间有一个30°的面内转动来减少和基片之间的失配度.在孪晶薄膜中存在的这些相互旋转形成的区域界面上会引起载流子强烈的散射作用,导致载流子迁移率的下降和平均自由程的缩短.利用X射线吸收精细结构技术证明了无论单晶还是孪晶的Zn0.96Co0.04O薄膜中所有的Co都以+2价替代进入了ZnO的晶格,而没有形成任何杂相.而对其磁性研究发现,孪晶的薄膜样品比高质量的单晶薄膜样品具有大得多的饱和磁矩.这充分说明孪晶薄膜中的铁磁性来源与缺陷有关.我们还对铁磁性耦合机制进行了探讨.
The thin films of Zn0.96Co0.04O thin films grown along the c-axis on sapphire Al2O3 substrates with different crystal planes were respectively prepared by molecular beam epitaxy. It was found that the thin films on the Al2O3 (1120) plane (a surface) were Two-dimensional layered epitaxial growth of high-quality single-crystal thin films, while the film on the Al2O3 (0001) plane (c-plane) has an interesting twins structure, some of the regions between each other with a 30 ° rotation to reduce And the mismatch between the substrates.The strong interdiffusion of carriers caused by the interfacial formation of these interfacial domains in the twin films results in the decrease of the carrier mobility and the shortening of the mean free path. X-ray absorption of fine structure technology proved that regardless of single crystal or twin Zn0.96Co0.04O film all +2 valences into the lattice of ZnO, without forming any heterophase. And its magnetic It is found that the twins' film samples have a much larger saturation moment than those of the high quality single crystal films, which shows that the source of ferromagnetism in the twin films is related to the defects. We also discussed the ferromagnetic coupling mechanism .