基片温度对Co掺杂ZnO薄膜室温铁磁性的影响

采用磁控共溅射法在Al2O3(0001)基片上沉积了Zn1-xCoxO(x=0.08～0.3%)薄膜,研究了基片温度对Co掺杂ZnO薄膜结构和磁性的影响.结果表明:Al2O3(001)基片很好地诱导了ZnCoO薄膜(002)取向生长,并且所有的薄膜均显示室温铁磁性.较低的基片温度不仅能有效抑制薄膜中Co2O3杂质相的产生,而且薄膜磁矩较大.紫外-可见光谱也表明,薄膜中Co2 取代了ZnO中Zn2 的位置.     

溶剂热法制备Co、Ni共掺杂ZnO纳米棒及其性能研究

采用溶剂热法制备Co、Ni共掺杂ZnO的纳米材料。样品的XRD图谱表明,不同浓度的掺杂都没有改变ZnO的晶体结构,样品均为六方纤锌矿结构;XPS结果揭示了钴和镍均以+2价离子形式存在,进一步证明了Co2+、Ni2+是以替代部分Zn2+的形式存在于晶格中;高分辨图像显示,所得样品为纳米棒结构,纳米棒长度约150 nm,直径约15 nm;mapping图像及EDS显示出Co2+、Ni2+已经掺杂成功而且在纳米棒中均匀分布;PL测试表明,Co2+、Ni2+的掺杂导致锌空位浓度的变化,从而使得紫外发光峰右移。     

溶胶凝胶法制备Co掺杂ZnO粉体及其磁性

Co掺杂ZnO(Zn1-xCoxO)是理论预测的具有室温铁磁性的少数稀磁半导体之一,在自旋电子器件领域有着重要应用前景。以醋酸锌和醋酸钴为原料,采用溶胶-凝胶法制备Zn0.95Co0.05O粉体,研究了煅烧温度对其物相组成、晶体结构和磁学性能的影响。结果表明:随着煅烧温度的升高,更多的Co2+进入ZnO晶格中,取代纤锌矿结构中的Zn2+进入四面体配位环境;煅烧温度为800℃时得到具有单一纤锌矿结构的Zn0.95Co0.05O粉体;所有的粉体均表现为顺磁性,随着煅烧温度的升高,顺磁性增强。     

Zn1-xCoxO纳米稀磁半导体的光催化性能

通过水热法合成了不同掺杂比例的一维Zn1-xCoxO(x=0,0.03,0.06和0.09)纳米棒,并通过X射线衍射(XRD)、高分辨透射电镜(HRTEM)、紫外可见光吸收光谱(UV-vis)和振动样品磁强计(VSM)等研究了样品的晶体结构、形貌、磁性能、光吸收性能和光催化性能。结果表明:不同掺杂比例的Zn1-xCoxO均为结晶良好的六方纤锌矿结构,Co2+以替代Zn2+的形式进入到ZnO晶格中。样品形貌为一维纳米棒状结构,分散性良好。Co掺杂ZnO使得样品的能带隙减小,可见光吸收增加。掺杂样品在室温下具有明显的铁磁性,掺杂样品能增强降解有机染料罗丹明B(RhB)的光催化活性。     

氨水和NaOH水溶液中生长ZnO薄膜的对比研究

研究在Zn(NO3)2/NaOH和Zn(NO3)2/NH3H2O水溶液体系中ZnO薄膜的生长条件.通过X射线衍射仪和扫描电镜对薄膜进行了表征.两种碱性体系生长的薄膜是六方纤锌矿结构;晶体垂直于衬底沿(002)方向择优生长,随着生长溶液浓度的增大,薄膜柱晶的直径会逐渐增大.NaOH系统生长的ZnO薄膜厚度较薄,致密度较小,NH3H2O系统生长的薄膜中棒晶排列较为密集.对于NaOH生长系统,锌的浓度由于受到限制,导致生长的柱晶直径较小.氨水系统中由于[Zn(NH3)4]2 的缓冲作用,获得的ZnO晶粒直径可以在纳米到微米范围内变化.     

电化学沉积Nd掺杂ZnO薄膜的结构和光学性质的研究（英文）

用电化学沉积方法制备出了Nd掺杂的ZnO薄膜,并研究其结构和光学性质。X射线衍射谱的结果表明Nd~(3+)替代Zn2+进入到ZnO晶格中,并没有引起杂相的出现。吸收谱的分析表明,随着掺杂浓度的增大,吸收峰向短波长方向移动,即发生蓝移。光致发光谱的结果表明随着Nd~(3+)掺杂浓度的增大,紫外峰强度减小,可见光部分强度增大了。     

Zn0.95Co0.05O纳米线和纳米管的电泳沉积法可控合成（英文）

以阳极氧化铝为模板通过电泳沉积法制备Zn0.95Co0.05O纳米线和纳米管,并对电泳沉积法制备纳米线(管)的机理进行研究。系统的结构表征表明所得的纳米管和纳米线是由8～15nm的纤锌矿纳米晶构成的多晶结构,Co2+离子以代位掺杂形式掺入晶格,取代了晶格中的Zn2+离子。磁性表征显示制备的纳米线和纳米管具有室温铁磁性。由于Co在纳米线(管)中表面择优分布,纳米管的磁性明显高于纳米线。     

Zn_(0.95)Co_(0.05)O纳米线和纳米管的电泳沉积法可控合成(英文)

以阳极氧化铝为模板通过电泳沉积法制备Zn0.95Co0.05O纳米线和纳米管,并对电泳沉积法制备纳米线(管)的机理进行研究。系统的结构表征表明所得的纳米管和纳米线是由8～15nm的纤锌矿纳米晶构成的多晶结构,Co2+离子以代位掺杂形式掺入晶格,取代了晶格中的Zn2+离子。磁性表征显示制备的纳米线和纳米管具有室温铁磁性。由于Co在纳米线(管)中表面择优分布,纳米管的磁性明显高于纳米线。     

Cu-Co共掺杂ZnO稀磁半导体的水热法制备与性能

采用水热法了制备不同掺杂比例的Zn0.95Cu0.05-xCoxO(x=0,0.025,0.05)稀磁半导体材料。X射线衍射(XRD)表明所有样品具有结晶良好的纤锌矿结构,随着Co掺杂量的增加点阵常数有所增大。高分辨透射电子显微镜(HRTEM)发现所有样品形貌为纳米棒状结构,分散性良好。X射线能量色散分析仪(EDS)测试结果说明样品中Cu2+、Co2+是以替代的形式进入ZnO晶格中。光致发光光谱(PL)研究发现在所有样品中都存在较强的紫外发光峰、蓝光发光峰和绿光发光峰,而且峰位发生蓝移。振动样品磁强计(VSM)研究结果表明掺杂样品在室温条件下存在具有铁磁性。     

Co~(2+)取代Ni~(2+)对MgNiCuZn铁氧体纳米微粒磁学性能的影响

通过化学共沉淀法制备了纳米级的Mg0.05CoxNi0.35-xCu0.2Zn0.4Fe2O4铁氧体超细粉末,采用X射线衍射仪和振动样品磁强计分析研究了Co2+取代Ni2+对铁氧体结构和饱和磁化强度的影响。结果表明,试样的晶格参数a和平均粒径Dx随Co2+取代量的增加而增大;饱和磁化强度Ms随Co2+取代量的增加单调增大。     

Fabrication of Co-doped ZnO nanorods for spintronic devices

Herein, single-crystalline Zn_1?xCo_xO (0.0≤x≤0.10) nanorods were prepared using a facile microwave irradiation method. Structural analyses by X-ray diffraction and transmission electron microscopy revealed the incorporation of Co²⁺ in the lattice position of Zn²⁺ ions into the ZnO matrix. Field emission scanning electron microscopy and TEM micrographs revealed that the length and diameter of the undoped ZnO nanorods were about ～2 μm and ～200 nm, respectively. For Co-doped ZnO, the length and diameter were found to increase with an increase of Co doping. The selected area electron diffraction pattern indicated that the Zn_1?xCo_xO (0.0≤x≤0.10) nanorods had a single phase nature with the preferential growth direction along the [0 0 1] plane. Raman scattering spectra confirmed the shift of the E ₂ ^high mode toward a lower wave number, suggested successful doping of Co ions at Zn site into the ZnO. Magnetic studies showed that Co doped ZnO nanorods exhibited room temperature ferromagnetism and the magnetization value increased with an increase in Co doping. The synthesis method presented here is a simple approach to prepare ZnO based diluted magnetic semiconductors nanostructures for practical application to spintronic devices.     

垂直生长于锌基底的Co掺杂ZnO纳米棒阵列显著室温铁磁性能

通过简单的水热合成法在锌片基底上一步制备了Co掺杂的ZnO纳米棒阵列。纳米棒在基底上均匀分布,取向一致,垂直于基底大面积生长。样品结构均为六方纤锌矿结构,具有高结晶质量,不含其它杂相。随着Co掺杂浓度的增加,紫外发射峰强度逐渐下降,近带隙发射峰的半峰宽也较纯ZnO变宽。拉曼光谱显示Co的掺杂使纳米棒出现了氧空位和锌填隙本征缺陷。随着Co浓度的增加这些缺陷也随之增加。掺杂纳米棒阵列的磁滞回线表明样品具有明显的铁磁特征,并有较大的矫顽力Hc~660 Oe。这种ZnO基稀磁半导体纳米棒阵列是一种在自旋电子器件中具有应用潜力的纳米材料。     

Morphology and optical properties of Co doped ZnO textured thin films

Depending on the ZnO seed-layers, a new kind of cobalt doped zinc oxide (Zn_1−xCo_xO) thin films with controllable morphology were prepared by a facile solvothermal method. A series of ZnO thin films with different Co contents were applied to study the effect of doped Co on morphology, structural and optical properties. It is found that the doped content plays an important role on morphology evolution of Zn_1−xCo_xO films. The results of scanning electron microscope (SEM) indicate that the Zn_1−xCo_xO films are highly uniform and porous. Co has been successfully doped into the ZnO lattice structure and revealed by X-ray diffraction (XRD) and energy dispersive spectrum (EDS). It can be found that Zn_1−xCo_xO thin films possess good crystalline quality through the characterization of transmission electron microscope (TEM) and high-resolution transmission electron microscopy (HRTEM). All of the samples show a stronger violet emission and ultraviolet absorption, and the violet emission peaks shift towards red with increasing of Co content. In addition, the magnetic result demonstrates that the prepared Co-doped ZnO thin films are room-temperature ferromagnetic materials.     

Eu掺杂ZnO薄膜与Si(100)衬底间扩散过程分析

利用雾化热解工艺,在Si(100)衬底上制备了Eu掺杂的ZnO薄膜,通过N2的作用,将前驱体溶液输送到衬底表面,同时为实现ZnO的晶化,衬底温度保持在350℃.通过RBS分析了薄膜和衬底之间的原子分布,结果显示了ZnO薄膜与Si衬底之间存在过渡层.对RBS数据的分析表明该过渡层的形成是由于Si向ZnO层中的扩散,表明Si向氧化物中的扩散是不能忽略的,即使在350℃的低温下.同时,作者利用Fick扩散方程对Si向Eu3 掺杂ZnO薄膜的扩散行为进行了分析,结果表明掺杂离子Eu3 具有阻止Si扩散的能力,其原因可能与Eu3 离子在晶界上的偏析有关.     

Boron and fluorine doped ZnO films obtained from zinc chloride precursor via chemical spray pyrolysis

Both boron (1, 2 and 3 at %) and fluorine (1, 3, 5 and 7 at %) doped zinc oxide thin films (ZnO:B:F) were fabricated using zinc chloride precursor by airbrush spray pyrolysis technique on glass substrates. X-ray diffraction (XRD) measurements show that all ZnO:B:F films have hexagonal wurtzite structure with a preferential growth along the [0 0 2] direction on glass substrates. Scanning electron microscope (SEM) results show that the morphologies of all doped films have a regular hexagonal shape. The optical measurements reveal that ZnO:B:F films have a direct band gap and optical energy gaps are increasing with boron and fluorine concentration. The optical transmittance of B and F doped ZnO films is measured very low due to columnar structure of prepared films. Moreover, it has been observed that the doping of ZnO films with boron and fluorine decreases the electrical resistance, and the lowest resistances of films were observed at 1%B–3%F and 2%B–3%F concentrations.     

Grain boundary defects-mediated room temperature ferromagnetism in Co-doped ZnO film

Zn_0.97Co_0.03O films with and without ZnO buffer layer have been fabricated by magnetron sputtering to investigate the role of grain boundary defects in ferromagnetic ordering in this system. The deposited wurtzite films with (0 0 2) preferred orientation all show intrinsic room temperature ferromagnetism based on the substitutional behavior of Co²⁺. We found that the ZnO/Co:ZnO film grows in smaller grain size, compared with Co:ZnO film, which leads to the increase in grain boundary defects. Meanwhile the increase in oxygen vacancies is confirmed by Co K-edge X-ray-absorption near-edge spectra and the enhancement of saturated magnetization is observed in ZnO/Co:ZnO film. Hence the most important factor for mediating ferromagnetism is proposed to be grain boundary defects, i.e., oxygen vacancies. Bound magnetic polaron mechanism is adopted to explain the intrinsic origin and the mediative effects of grain boundary defects on ferromagnetism in Co-doped ZnO films.     

Elaboration and characterization of Al doped ZnO nanorod thin films annealed in hydrogen

ZnO thin films doped with Al concentrations of 1.0, 2.0, 3.0, 4.0, 5.0 at% were prepared by a sol-gel spin-coating method on glass substrates and respectively annealed at 550 °C for 2 h in hydrogen and air. The X-ray diffraction and selected-area electron diffraction results confirm that the Al doped ZnO thin films are of wurtzite hexagonal ZnO. The scanning electron microscope results indicate that the Al doped ZnO nanorod thin films can be got by annealing in hydrogen rather than in air. The optical properties reveal that the Al doped ZnO thin films have obviously enhanced transmittance in the visible region. The electrical properties show that the resistivity of 1.0 at% Al doped ZnO thin films has been remarkably reduced from 0.73 Ω m by annealing in air to 3.2 × 10⁻⁵ Ω m by annealing in hydrogen. It is originated that the Al doped ZnO nanorod thin films annealed in hydrogen increased in electron concentration and mobility due to the elimination of adsorbed oxygen species, and multicoordinated hydrogen.