射频磁控溅射制备(In,Co)共掺ZnO薄膜的电学和磁学性质

Electrical and magnetic properties of(In,Co)co-doped ZnO films deposited using radio frequency magnetron sputtering

(In,Co)共掺的ZnO薄膜(ICZO薄膜)在100℃下通过射频(RF)溅射沉积至玻璃基板上.沉积过程采用In、Co、Zn三靶共溅射.通过调节靶功率,获得了不同In含量的ICZO薄膜.研究了不同In含量下薄膜电学性质和磁学性质的变化.分别使用扫描电子显微镜(SEM)、高分辨透射电子显微镜(HR-TEM)、原子力显微镜(AFM)、电子探针扫描(EPMA)、X射线衍射仪(XRD)、霍尔测试(Hall measurement)和振动样品磁强计(VSM)对薄膜的成分、形貌、结构、电学特性和磁学特性进行了表征和分析.详细分析了薄膜中载流子浓度对磁学性质的影响.实验结果表明,随着薄膜中In含量的提高,薄膜中载流子浓度显著提高,薄膜的导电性得到优化.所有的薄膜均表现出室温下的铁磁特性.与此同时,束缚磁极化子(BMP)模型与交换耦合效应两种不同的机制作用于ICZO半导体材料,致使薄膜的饱和磁化强度随载流子浓度发生改变,并呈现在三个不同的区域.

Diluted magnetic semiconductors(DMSs)have attracted much attention in recent years due to their dual control of charge and spin degrees of freedom in carriers.Potential applications of DMSs include spin light-emitting diodes,spin field-effect transistors,magnetoresistance random access memory,and ultrafast optical switches.However,the Curie temperature(Tc)of most DMSs below ambient temperature limits the efficiency of these devices.Thus,the biggest challenge for developing DMS materials has been producing host materials that exhibit ferromagnetic behavior above ambient temperature.A series of theoretical simulations and experiments show that the Tc value of ZnO-based DMSs could satisfy this requirement.Incorporation of selective transition metal elements(e.g.,Fe2+,Co2+,Ni2+,and Mn2+)has been confirmed as an effective way to enhance the magnetic properties of ZnO.In the present research,(In,Co)co-doped ZnO(ICZO)films were deposited by radio frequency sputtering at 100℃on a glass substrate.The sputtering process was performed through In,Co,and ZnO co-sputtering.The presence of ICZO films has been adjusted by changing the target sputtering power.The variation of electric and magnetic properties of the film was studied with different In content.The composition,morphology,structure,electric and magnetic properties of films were characterized by field emission scanning electron microscopy,high-resolution transmission electron microscopy,atomic force microscopy,electron probe microanalyzer,X-ray diffractometer,Hall effect analysis,and vibrating sample magnetometer.The effect of carrier concentration on the magnetic properties of the film was analyzed extensively.These results show that,in the presence of In,the carrier concentration increases,thereby optimizing films’conductivity.All the films present ferromagnetic behavior at room temperature.Besides,with an influence of bound magnetic polaron model and carrier-mediated exchange mechanisms on the film’s saturation magnetization,carrier-concentration dependent behavior can be expressed in three different regions.