【作者】 张士晶；

【导师】 姚斌；

【作者基本信息】 吉林大学 ， 凝聚态物理， 2005， 硕士

【摘要】 本文采用标准固相烧结法制备了Mn 和Co 离子掺杂的ZnO 基稀磁半导体,并对样品进行了结构表征和性能的研究。Mn 掺杂样品Zn_1-XMn_XO（x=0.05-0.10）的XRD 研究结果表明,样品中均有少量的第二相ZnMn₂O₄ 存在,因而Mn 离子在ZnO 晶格中的固溶度要低于5%;对样品Zn_0.9Mn_0.1O 的磁性研究发现,在150K 到室温的温度范围样品表现出反铁磁相互作用的现象;在低磁场其M-H 的变化类似铁磁材料的情形,但与铁磁材料不同的是随着H 的增加,M 并没有趋于饱和,而是像顺磁材料那样M 随H 的增加而线性增加,随着温度的减小,出现类铁磁M-H 变化的磁场减小,当T=10K 时,M 随H 的变化完全类似顺磁材料的变化。Co 掺杂样品Zn_1-XCo_XO（x=0.02-0.16）均为单一相,表现出n-型半导体的电学特性,电子浓度～10¹⁷/cm³,迁移率在32-58cm²/（Vs）;样品在高温区表现出与ZnO 不同电导-温度变化规律,意味着Co 在ZnO 中可能形成较深的施主能级;样品在室温的M-H 曲线表现出顺磁的特性,说明其居里温度在室温以下。更多还原

【Abstract】 Diluted magnetic semiconductors （DMS） are semiconductors in which transition –metal ions substitute cations of the host Semicnductor materials. Localized d electrons of the magnetic ions couple with the extended electrons in the conduct band .These couplings lead to a number of peculiar and interesting properties, such as, ferromagnetic, magneto-optical and magneto-electrical effects. Dietl et al. suggested GaN and ZnO as candidates having a high Curie temperature （Tc） and a large magnetization, and lately a few experimental results were reported. A wide-gap Π-VI semiconductor, ZnO attracts attention as a material with possible application in optoelectronic devices such as solar cells, ultraviolet emitting diodes, and transparent high-power electronic devices. The discovery of ferromagnetism （FM） at temperatures above 100K in the Ш-V semiconductor Ga_1-xMn_xAs. Theoretical predictions of room-temperature FM in diluted magnetic semiconductors （DMSs）² recently focused attention on magnetic-ion-substituted ZnO with a wurtzite structure similar to GaAs. The Zn_1-xTM_xO samples in this study were prepared using a standard solid-state reaction technique. Mixtures of ZnO and MnO₂, or Co₃O₄, for TM=Mn and Co, respectively, were fired in air several times at elevated temperatures of 900℃, 1100℃, and 1300℃for about 2 to 4 hours. Afer samples were synthesized ,we would define their crystal structure by XRD and their physical properties,including magnetic properties and so on . For Mn-doped ZnO with 5 at.%,6 at.%,8 at.%,10 at.% fired in the air. We have found that XRD patterns already presented the second phase ZnMn2O4 belonged to Tetragonal crystal system in the sample Zn1-xMnxO（x=0.05）,but the diffraction intensity of the impurity ZnMn2O4 is weak, which indicated that the solubility limit the Mn ions in ZnO was less than 5%. We studied the magnetic properties of Zn0.9Mn0.1O which have the impurity ZnMn2O4.The sample Zn0.9Mn0.1O revealed the presence of antiferromagnetic interactions by M-T curve measure. At lower temperatures inverse DC susceptibility curve toward a temperature close to Zero. And we have studied M-H curve of the sample Zn0.9Mn0.1O under RT、70K and 10K temperature. The result revealed that the M followed H leads to a change similar to ferromagnetic material at the beginning of adding to magnetic field and below 200Oe. But there is a difference that M didn’t go to a saturation state followed the increased H with ferromagnetism material. It is like that the curve exhibits a paramagnetic behavior,M being linearity increasing followed increasing H.And that the curve exhibits that magnetic field minished which is similar to a ferromagnetic M-H change .When T is 10K tempreture,the change of M followed H entirely similar to paramagnetic behavior.We will more discuss the correlative physics mechanism of above phenomena. The single-phase samples Zn1-XCoxO（x=0.02, 0.04, 0.06, 0.08, 0.10, 0.16,x=cobalt content） were prepared using a standard solid-state reaction technique. The crystal structures of co-doped ZnO were characterized by XRD. The diffraction pattern reveals only the presence of the peaks corresponding to hexagonal ZnO and no second phase peaks.We have found that Co doped ZnO samples are all n-type semiconductors Their carrier concentration are about to be e+17/（cm-3） and the mobility is from 32 to 58cm2/（Vs）.更多还原