单晶和孪晶的Zn_(0.96)Co_(0.04)O稀磁半导体薄膜的制备与研究  

Synthesis and electric,magnetic properties of single crystalline and twin-crystalline Co-doped ZnO thin films

作　　者：路忠林[1,2,3] 邹文琴[3] 徐明祥[1] 张凤鸣[3] 

机构地区：[1]东南大学物理系,南京210096 [2]成功大学物理系 [3]南京大学物理系,南京210093

出　　处：《物理学报》2009年第12期8467-8472,共6页Acta Physica Sinica

基　　金：国家自然科学基金(批准号:10804017);江苏省自然科学基金(批准号:BK2007118);高等学校博士学科点专项科研基金(批准号:20070286037);江苏省"青蓝工程"(批准号:1107020060);江苏省"六大人才高峰"计划(批准号:1107020070);教育部新世纪优秀人才支持计划(批准号:NCET-05-0452)资助的课题~~

摘　　要：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.c-oriented Co-doped ZnO（Zn0.96Co0.04O） thin films have been grown on the a-plane and c-plane sapphire substrates using molecular-beam epitaxy,respectively. In contrast to single crystalline Zn0.96Co0.04O film grown on a-plane sapphire,the film grown on c-plane sapphire were found to be twin-crystalline;some domains have a 30° rotation to reduce the large mismatch. The presence of these rotation domains in the twin-crystalline ZnO thin film causes much more carrier scattering at the boundaries,leading to much lower mobility and smaller mean free path of the mobile carriers,as compared with those of the single crystalline one. X-ray absorption fine structure studies revealed that most Co ions were in divalent state and actually substituted into ZnO lattice without formation of any detectable secondary phase. As compared with just a small saturation moment in the single crystalline Zn0.96Co0.04O thin film,the much stronger ferromagnetism in the twin-crystalline one indicates that the ferromagnetic origin should be highly correlated with structural defects in the twin-crystalline film. The possible magnetic mechanisms were discussed.

关 键 词：Co掺杂ZnO 稀磁半导体 X射线吸收精细结构 单晶和孪晶薄膜 

分 类 号：O484[理学—固体物理]