共查询到20条相似文献,搜索用时 62 毫秒
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利用磁控溅射法,采用亚分子分层掺杂技术交替溅射Co靶和ZnO靶,在Si衬底上制备了不同氢氩流量比的H:ZCO薄膜样品,研究了氢氩流量比对薄膜结构特性和磁学性能的影响。所制备的薄膜样品具有c轴择优取向。由于H对表面和界面处悬挂键的钝化作用,随H2流量比的增加,薄膜的择优取向变差。磁性测量结果显示,薄膜样品的铁磁性随着氢氩流量比的增大而增强。XPS结果表明,随着H含量的增大,金属态Co团簇的相对含量逐渐增加,而氧化态Co离子的相对含量逐渐减小。H:ZCO样品中的铁磁性可能来源于Co金属团簇,H的掺入促使ZnO中的Co离子还原成Co金属团簇,从而增强了薄膜样品的室温铁磁性。 相似文献
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采用共沉淀方法制备了名义组分为Zn1-xMnxO(x=0.001,0.005,0.007,0.01)的Mn掺杂的ZnO基稀磁半导体材料,并研究了在大气气氛下经过不同温度退火后样品的结构和磁性的变化.结果表明:样品在600℃的大气条件下退火后, 仍为单一的六方纤锌矿结构的ZnO颗粒材料;当样品经过800℃退火后,Mn掺杂量为0.007,0.01的样品中除了ZnO纤锌矿结构外还观察到ZnMnO3第二相的存在.磁性测量表明,大气条件下600℃退火后的样品,呈现出室温铁磁性;而800℃退火后的样品,其室温铁磁性显著减弱,并表现为明显的顺磁性.结合对样品的光致发光谱的分析,认为合成样品的室温铁磁性是由于Mn离子对ZnO中的Zn离子的替代形成的.
关键词:
ZnO
掺杂
稀磁半导体
铁磁性 相似文献
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采用水热法,在温度430 ℃,填充度35%,矿化剂为3 mol·L-1KOH,前驱物为添加适量的FeCl2·6H2O的Zn(OH)2,反应时间24h,合成了Zn1-xFexO和Zn1-xFexO:Cu稀磁半导体晶体.当在Zn(OH)2中添加一定量的FeCl2·6H2O为前驱物,水热反应产物为掺杂Fe的Zn1-xFexO多种形态晶体混合物,其个体较大的晶体中的Fe原子百分比含量为0.49%—0.52%.采用超导量子干涉磁强计测量了材料的磁性,晶体的磁化强度随温度下降而减小.在前驱物中同时加入适量比例的Cu化合物,合成了共掺杂Cu的Zn1-xFexO:Cu,和Zn1-xFexO相比,其室温下的磁化强度有明显的提高,且在室温下具有铁磁性.
关键词:
氧化锌
水热
稀磁半导体
晶体 相似文献
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Ghulam Murtaza Rai Muhammad Azhar Iqbal Yong-bing Xu Iain Gordon Will Qasim Mahmood 《化学物理学报》2012,25(3):313-317
采用热蒸镀技术和后续氨退火制备了Ho掺杂GaN稀磁半导体薄膜. X射线衍射分析表明,所有的峰属于六角纤锌矿结构. 利用扫描电子显微镜和能量色散谱分别进行了表面形貌和成分分析. 用振动样品磁强计在室温测定了Ga1-xHoxN(x=0.0,0.05)的室温铁磁性. 磁性测量结果表明,未掺杂薄膜GaN具有抗磁性行为,而Ho掺杂Ga0.95Ho0.05N的薄膜表现出铁磁行为. 相似文献
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稀磁半导体Zn1—xCoxSe的光谱特性 总被引:2,自引:0,他引:2
本文首次报道一类新型半导体材料:含Co^+6+离子的稀磁半导体Zn1-xCoxSe晶体的光谱特性研究实验结果。对组分x=0.001,0.0097,0.030,0.037系列样品,在73K-300K范围内分别在可见和近红外区测量了吸收光谱和光致发光谱。实验观测到一系列与x值无关的吸收峰和光致发光峰,两者一一对应,它们分别对应于具有Td对称的晶体场中Co^+^+离子不同能级间的跃迁,对这些峰进行了初步 相似文献
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从实验和理论上阐述了氧空位对Co掺杂ZnO半导体磁性能的影响.采用磁控溅射法在不同的氧分压下制备了Zn095Co005O薄膜,研究了氧分压对薄膜磁性能的影响.实验结果表明,高真空条件下制备的Zn095Co005O薄膜具有室温铁磁性,提高氧分压后制备的薄膜铁磁性逐渐消失.第一性原理计算表明,在Co掺杂ZnO体系中引入氧空位有利于降低铁磁态的能量,铁磁态的稳定性与氧空位和Co之间的距离密切相关.
关键词:
Co掺杂ZnO
稀磁半导体
第一性原理计算
氧空位缺陷 相似文献
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利用共沉淀法并在5vol.%H2/Ar气流中于300 ℃退火3 h,制备了Zn1-xCoxO稀磁半导体. 扫描电子微探针分析表明,对Co的名义组分分别为0.05,0.10,0.15的样品,其实际组分分别为x=0.054, 0.100和0.159. X射线衍射表明, 主相为纤锌矿结构, x=0.100和 0.159的样品中含有CoO杂相. X射线光电子谱显示出Co有3种状态: 替代进入Z
关键词:
稀磁半导体
ZnO
共沉淀法
磁性来源 相似文献
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本文以ZnCl2, CrCl3. 6H2O和氨水缓冲溶液为原料, 在4T脉冲磁场下水热法制备了Cr掺杂ZnO稀磁半导体晶体, 通过X射线衍射分析、扫描电子显微镜观察及采用振动样品磁强计进行磁性分析等, 探讨了脉冲磁场对其微观结构及磁性能的影响. 结果表明: Cr掺杂ZnO稀磁半导体晶体仍保持ZnO的六方纤锌矿结构, 脉冲磁场具有促进晶粒生长及取向排列的作用, 4T脉冲磁场条件下合成的Cr掺杂ZnO稀磁半导体具有良好的室温铁磁性, 其饱和磁化强度(Ms)为0.068 emu/g, 而无脉冲磁场情况下制备的样品室温下呈顺磁性, 并且, 脉冲磁场下制备将稀磁半导体的居里温度提高了16 K. 相似文献
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《Current Applied Physics》2014,14(2):176-181
In this study, Zirconium doped Zn1−xZrxO (with x = 0.00–0.10) samples have been prepared by formal solid-state reaction technique. The Zr doped ZnO samples annealed at 1100 °C and characterized by different characterization techniques, such as X-ray diffraction (XRD), Scanning electron microscope (SEM), Vibrating sample magnetometer (VSM) and Fourier transform infrared spectroscopy (FTIR). The X-ray diffraction (XRD) used to study the structural properties. XRD pattern showed that lattice parameters, “a”, “c”, unit cell volume and Zn–O bond length increase with doping content (x ≤ 0.04) where as these decrease with x > 0.04. On the other hand, reverse trend observed with lattice distortion. The crystallite size decreases with increasing doping content of Zr. FTIR employed to investigate functional chemical bonding properties of different elements and compounds present in materials. The low, medium and high frequency absorption bands observed at 630, 1500 and 3435 cm−1, which were the common features of Zn–O, H–O–H and O–H bond respectively. SEM used to study surface morphology and measured grain size of specimen. The surface becomes dense and grain size decreases with increasing degree of Zr contents. The SEM micrograph also shows the presence of spherical micro size particles and formation of pores in samples. Magnetic properties were obtained using VSM. The samples exhibit room temperature ferromagnetism. The magnetic hysteresis loops show variation in the value of magnetic parameter. The saturation magnetization (Ms) and coercivity (Hc) decrease, while remanence magnetization (Mr) shows gradually increasing trend with Zr content. VSM measurement reveals that sample Zn0.96Zr0.4O show better result as compared to x = 0.06–0.10. 相似文献
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Room-temperature anomalous Hall effect and magnetroresistance in (Ga, Co)-codoped ZnO diluted magnetic semiconductor films 下载免费PDF全文
This paper reports that the(Ga,Co)-codoped ZnO thin films have been grown by inductively coupled plasma enhanced physical vapour deposition.Room-temperature ferromagnetism is observed for the as-grown thin films.The x-ray absorption fine structure characterization reveals that Co 2+ and Ga 3+ ions substitute for Zn 2+ ions in the ZnO lattice and exclude the possibility of extrinsic ferromagnetism origin.The ferromagnetic(Ga,Co)-codoped ZnO thin films exhibit carrier concentration dependent anomalous Hall effect and positive magnetoresistance at room temperature.The mechanism of anomalous Hall effect and magneto-transport in ferromagnetic ZnO-based diluted magnetic semiconductors is discussed. 相似文献
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Jong-Han Lee Sangwon ShinKeun Hwa Chae Donghwan KimJonghan Song 《Current Applied Physics》2012,12(3):924-927
1 MeV Cu2+ ions have been implanted into un-doped ZnO and Ga-doped ZnO films with a dose of 1 × 1017 ions/cm2 at room-temperature. Cu ion-implanted Ga-doped ZnO had ferromagnetism at room-temperature and the saturation magnetization of this sample was estimated to be 0.12 μB per Cu, while the Cu ion-implanted un-doped ZnO did not show ferromagnetic behavior. Near-edge X-ray fine structure (NEXAFS) spectroscopy revealed that a partial amount of implanted Cu ions existed as Cu2+ (d9) state in Ga-doped ZnO film. On the other hand, almost Cu atoms existed as Cu1+ (d10) state in un-doped ZnO film. However, the subsequent annealing at temperature above 800 °C on this ferromagnetic sample induced the annihilation of ferromagnetism due to the formation of non-ferromagnetic Cu2O phase. 相似文献
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本文以Zn(CH3COO)2·2H2O, Mn(CH3COO)2·4H2O和氨水缓冲溶液为原料, 在4 T脉冲磁场下利用水热法制备了Mn掺杂ZnO稀磁半导体晶体, 通过X射线衍射、 扫描电子显微镜、透射电子显微镜、拉曼光谱、荧光分光光度计及振动样品磁强计等对样品的微观结构及磁性能等进行了表征, 结果表明: Mn掺杂ZnO稀磁半导体晶体仍保持ZnO六方纤锌矿结构, 4 T脉冲磁场下合成的Mn掺杂ZnO稀磁半导体晶体具有明显的室温铁磁性, 其饱和磁化强度(Ms)为0.028 emu/g, 比无脉冲磁场下制备的样品提高一倍以上, 且4 T 脉冲磁场将样品的居里温度提高了15 K. 相似文献
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A series of Mn-doped ZnO films have been prepared in different sputtering plasmas by using the inductively coupled plasma enhanced physical vapour deposition. The films show paramagnetic behaviour when they are deposited in an argon plasma. The Hall measurement indicates that ferromagnetism cannot be realized by increasing the electron concentration. However, the room-temperature ferromagnetism is obtained when the films are deposited in a mixed argon-nitrogen plasma. The first-principles calculations reveal that antiferromagnetic ordering is favoured in the case of the substitution of Mn^2+ for Zn^2+ without additional acceptor doping. The substitution of N for O (NO^-) is necessary to induce ferromagnetic couplings in the Zn-Mn-O system. The hybridization between N 2p and Mn 3d provides an empty orbit around the Fermi level. The hopping of Mn 3d electrons through the empty orbit can induce the ferromagnetic coupling. The ferromagnetism in the N-doped Zn-Mn-O system possibly originates from the charge transfer between Mn^2+ and Mn^3+ via NO^-, The key factor is the empty orbit provided by substituting N for O, rather than the conductivity type or the carrier concentration. 相似文献
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First-principles calculations based on density functional theory are performed to study the origin of ferromagnetism in boron-doped ZnO. It is found that boron atoms tend to reside at Zn sites. The induced Zn vacancy is a key factor for ferromagnetism in Zn1-xBxO (0相似文献
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A.M. Abdel Hakeem 《Journal of magnetism and magnetic materials》2010,322(6):709-714
In view of recent controversies on above room-temperature ferromagnetism (RTFM) in transition-metal-doped ZnO, the present paper aims to shed some light on the origin of ferromagnetism by investigating annealing effects on structure and magnetism for polycrystalline Zn1−xMnxO powder samples prepared by solid-state reaction method and annealed in air at different temperatures. Magnetic measurements indicate that the samples are ferromagnetic at room temperature (RTFM). Room temperature ferromagnetism has been observed in the sample annealed at a low temperature of 500 °C with a saturated magnetization (Ms) of 0.159 emu/g and a coercive force of 89 Oe. A reduction in RTFM is clearly observed in the sample annealed at 600 °C. Furthermore, the saturation magnetic moment decreases with an increase in grain size, suggesting that ferromagnetism is due to defects and/or oxygen vacancy confined to the surface of the grains. The experimental results indicate that the ferromagnetism observed in Zn1−xMnxO samples is intrinsic rather than associated with secondary phases. 相似文献