【作者】 王颖蕾；

【导师】 陈希明；

【作者基本信息】 天津理工大学 ， 微电子学与固体电子学， 2010， 硕士

【摘要】 稀磁半导体（DMS）材料可利用电子自旋所需能量小,易控制等优点实现许多新的多功能器件。其中,纤锌矿结构的ZnO由于具有生长温度较低,激子束缚能较大（60meV）,禁带较宽（3.27eV）支持较大的磁性掺杂浓度,被预言可实现较高居里温度等优点,成为研究II-VI族DMS的理想选择。本文先介绍了目前人们对稀磁半导体的有关研究,着重介绍ZnO基DMS研究情况。为寻找一种较好的制备掺杂ZnO稀磁材料的工艺方案,我们用磁控分层溅射及共溅法制备了Cr掺杂ZnO薄膜,并用溶胶-凝胶法（sol-gel）制备Fe掺杂ZnO薄膜。研究薄膜样品的结构、成分与磁学性质。1.制备工艺研究（1）采用分层磁控溅射,靶材为Cr及ZnO,制备不同浓度Cr掺杂ZnO薄膜。射频ZnO靶的溅射功率约175W,直流Cr靶的溅射功率约为165W,通过改变每层共溅时间（10s-30s）来改变掺杂浓度。经测试分析得到每次共溅时间为20s,即掺杂浓度为2%时,衬底为硅片时的样品结晶效果最好,但衬底为载玻片时的样品铁磁性最强。（2）采用共溅射靶材为Cr及ZnO,制备不同浓度Cr掺杂ZnO薄膜。通过固定射频ZnO靶的溅射功率约175W,改变直流Cr靶的溅射功率为10W至48W,来改变掺杂浓度。经测试分析得到直流Cr靶功率为24w,即掺杂浓度为2%时,样品结晶效果最好,但直流Cr靶功率为10w,即掺杂浓度为1%时的样品铁磁性最强。（3）采用二水醋酸锌与FeCl₂.4H₂O为前驱体,乙二醇甲醚为溶剂,乙醇胺为稳定剂,用溶胶凝胶法制备Fe掺杂ZnO薄膜。经测试分析得到衬底为硅片,提拉法制备的薄膜结晶较好。2.室温磁性研究（1）衬底分别为硅片及载玻片,分层溅射掺Cr均为2%时,载玻片上样品的磁性能更好一些,可能衬底晶格常数与ZnO的接近程度不同,导致在同种工艺下生长的薄膜微结构的不同,掺杂离子的分布不同,从而影响到室温磁性的不同。（2）衬底均为载玻片,掺Cr均为2%时,用分层溅射制备的样品磁性能比共溅射制备的样品磁性能要好。这可能是由于共溅射制备的样品掺杂更均匀些,其溅射功率也比分层溅射小一些,最终造成制备的薄膜样品结构及缺陷不同,也会影响其室温磁性的不同。（3）分析认为Cr:ZnO掺杂体系的室温铁磁性来源于其本质属性,即铁磁性交换与反铁磁性交换作用的竞争。更多还原

【Abstract】 Diulted magnetic semiconductors can realize many new multifunctional components by using the spin characteristic of electrons which consumes low energy and is easy to control.Among them,wurtzite ZnO is people’s ideal choice in II-VI based DMS study and has been focus of attention because of its merits ,such as relatively low growh temperature,a large exciton binding energy of 60meV,a wide band gap of 3.27ev,and theoretical works predicted it can realize high-temperature FM.We first introduce the study about diulted magnetic semiconductors at present, especially the study about ZnO based DMS. In order to find a better method to prepare doping ZnO diluted magnetic materials,we prepared Cr doped ZnO films using multilayer-sputtering technique and magnetron cosputting technique ,and prepared Fe doped ZnO films using sol-gel method , studied the structure,component and magnetism of the samples. 1.Study on preparation methods(1)Cr-doped ZnO films of different concentration were prepared by multilayer-sputtering technique .RF sputtering power is about 175W, DC sputtering power is about 165W. The concentration is controlled by changing cosputting time of every layer(10s-30s).Through analyses, we found when the cosputting time of every layer is 20s and the concentration is 2%,the crystallization of the sample on silicon is the best,but the ferromagnetism of the sample on glass is the best .(2)Cr-doped ZnO films of different concentration were prepared by magnetron cosputting technique,RF sputtering power is about 175W, and DC sputtering power is changed from 10W to 48W to change the concentration. Through analyses,we found when the DC power is 24W and the concentration is 2%, the crystallization of the sample is the best ,but when the DC power is 10W and the concentration is 1%,the ferromagnetism of the sample is the best .(3)Fe-doped ZnO films were prepared by sol-gel method.The zinc acetate,2-methoxyethanol,ferrous choride were used as the raw materials.Through analyses,we found the crystallization of the samples on silicon prepared by dipping method is better.2.Study on room-temperature magnetism(1)When the preparing method is multilayer-sputtering technique,and the concentration is 2%,the magnetism of the sample on glass substrate is better than the sample’s on silicon.Although they are prepared by the same method ,their structures can be different due to the different lattice mismatches of the different substrates.And the different distribution of doping ions may have some effect on their magnetism.(2)When the substrate is glass,and the concentration is 2%,the magnetism of the sample perpared by multilayer-sputtering technique is better than that prepared by cosputtering technique.Because when the preparing method is cosputtering technique,it can be more equably doped,and the sputtering power is lower,the samples prepared by different sputtering techniques can have different structures,and this can have some effect on their magnetism.(3)We analysed the room-temperature magnetism of Cr:ZnO films,and thought it’s their nature, and it roots in the competition between antiferromagnetic interaction and ferrmagnetic interaction.更多还原