共查询到19条相似文献,搜索用时 75 毫秒
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纤锌矿(WZ)/闪锌矿(ZB)结构以及WZ/ZB超结构广泛存在于一维Ⅲ-Ⅴ族半导体材料中。本文采用TEM和CL(阴极荧光谱)准原位表征的方法,对GaN纳米线的各种结构进行了系统的表征,并且建立了材料纳米结构与对应发光性质之间的直接联系。研究发现相对于纯WZ结构的GaN单根纳米线,具有WZ/ZB结构纳米线的CL出现了蓝移。通过对CL发光谱的蓝移现象的分析和研究表明,蓝移是由于高密度的WZ/ZB结构单元及其各种超结构所引起的特殊效应。 相似文献
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本文使用先进的球差校正环境透射电子显微镜(AC-ETEM)与原位电化学测试平台,在环境透射电镜中以SnO2纳米线作为空气正极,构建起一纳米K-O2金属空气电池,原位观测该电池在氧还原反应(ORR)过程中的微观变化行为。实验结果表明:在ORR过程中,SnO2纳米线首先转化为Sn单质颗粒与K2O;因纳米尺度的Sn单质颗粒具有优异的催化活性,在O2氛围中纳米线的表面生成了大量的KO2。但由于KO2不能稳定存在,会迅速分解成K2O2并释放O2,导致材料发生巨大的体积膨胀。相关实验结果为宏观K-O2电池的设计与改性提供了直观的实验证据。 相似文献
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在La0.7Sr0.3MnO3锰氧化物中掺杂其它稀土元素来提高和改善巨磁电阻效应,近年来已成为研究的热点并有相关报道。Huang等人提出了Lu的掺杂量与磁阻性能的直接关系,指出这种联系主要来自于两种磁有序相的共存和相互竞争。然而,其内部微观结构,缺陷(孪晶,层错等)及成分分布尚不 相似文献
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使用强碱氢氧化钾为沉淀剂,通过水热法成功合成了具有六角形貌的过渡金属氢氧化物Ni(OH)2及Co(OH)2片状纳米晶.利用X射线粉末衍射仪和透射电子显微镜对样品的结构和形貌进行了表征.透射电镜观察结果显示Ni(OH)2相为规则六角纳米片,Co(OH)2相为纳米片和纳米棒的混合物.选区衍射结果指出Ni(OH)2及Co(OH)2纳米晶体均为单晶体.Ni(OH)2及Co(OH)2纳米片的产率分别达到了70%和90%.将实验结果同前人的过渡族金属氢氧化物纳米片报道进行了比较,提出了一个新的片状纳米晶的形成机制,指出在正常的沉淀条件下,Ni(OH)2及Co(OH)2纳米晶的稳定形貌总为六角片状. 相似文献
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β-Ga2O3的力学性能关系到相关电子器件的制造、封装以及应用,然而目前关于β-Ga2O3单晶的力学变形机制研究还相对匮乏。本文研究了(100)β-Ga2O3单晶在压应力作用下的力学行为,发现其极易沿着(100)B面脆断,并计算得到该材料的断裂应力范围为314.1~615.1 MPa。进一步揭示了不同长径比、不同直径对β-Ga2O3纳米柱力学变形行为的影响,实验结果表明:当长径比>2时,β-Ga2O3纳米柱在不同直径下均沿着(100)B面发生脆断;当长径比<2且直径<200 nm时,(100)β-Ga2O3发生脆性向塑性的转变,表现为先沿着■面发生滑移,之后沿着(100)B面断裂。最后,讨论了晶体学取向对于小尺寸β-Ga2O3塑性的影响,研究结果为理解β-Ga 相似文献
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通过水热法制备了单晶介孔钛酸铅(PbTiO3)纳米线,利用原位透射电子显微技术对其进行了电输运性能研究。结果表明,单根介孔PbTiO3纳米线表现出非线性、不对称的I/V特性;小偏压下表现为欧姆特性,I-V数据满足线性关系;在较高偏压下表现为肖特基发射,且ln(J)-E1/2数据满足较好线性规律;在更高偏压下,由于铁电疲劳和热发射现象增强,表现为混合发射; PbTiO3纳米线整体表现出良好的铁电性能,对铁电纳米器件电学性能的调控和优化有一定的参考意义。 相似文献
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在自增韧陶瓷的烧结过程中,添加β-Si3N4晶种有利于高温下长柱状晶的形成与生长,可以改善陶瓷的强度和韧性;本文以Lu2O3为添加剂,通过对原始Si3N4粉进行热处理,制备出转相充分、具有柱状形貌β-Si3N4晶种,重点研究了Lu2O3对氮化硅相变和晶种形貌的影响.实验结果表明,以Lu2O3为添加剂,在1750
℃下热处理2 h能得到具有较纯β相含量和大长径比的β-Si3N4晶种. 相似文献
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通过透射电子显微学方法研究纳米材料内部结构有助于理解界面与缺陷对纳米材料性能的影响.在碳化硼五次孪晶纳米线体系中,为了缓解5°角度过剩引起的五次孪晶轴心区域的弹性应变能,在纳米线内部会产生一些结构缺陷.本文通过系列电子衍射分析结合暗场成像技术揭示了碳化硼五次循环孪晶纳米线中的一种结构弛豫模式.孪晶轴向纳米线边缘偏移从而... 相似文献
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通过透射电子显微学方法研究纳米材料内部结构有助于理解界面与缺陷对纳米材料性能的影响。在碳化硼五次孪晶纳米线体系中,为了缓解5°角度过剩引起的五次孪晶轴心区域的弹性应变能,在纳米线内部会产生一些结构缺陷。本文通过系列电子衍射分析结合暗场成像技术揭示了碳化硼五次循环孪晶纳米线中的一种结构弛豫模式。孪晶轴向纳米线边缘偏移从而导致其中2片单晶结构单元的缺失,形成仅具有3个单晶结构单元的非完整循环孪晶结构。统计分析发现此类结构弛豫现象少量存在于1100℃固相烧结合成的碳化硼五次孪晶纳米线中,从能量角度定性分析表明这可能与该结构弛豫发生过程中会产生具有较高能量的界面及表面有关。 相似文献
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Jrg K.N. Lindner Djamila Bahloul-Hourlier Daniel Kraus Michael Weinl Thierry Mlin Bernd Stritzker 《Materials Science in Semiconductor Processing》2008,11(5-6):169
Silicon nanowires (SiNWs) were grown on Si(1 0 0) and Si(1 1 1) substrates by chemical vapour deposition (CVD) via the vapour–liquid–solid (VLS) mechanism with small gold particles used as seeds. In order to control the diameter of nanowires, their density on the substrate and their orientation we controlled the size and the distribution of Au seed particles. This was accomplished using nanosphere lithography (NSL) by which regular arrays of Au nanoparticles can be generated. This allowed us to grow single-crystalline SiNWs perpendicular to the surface of Si(1 1 1) substrates. The SiNWs and their Au caps were studied with respect to their morphology and composition using TEM, HREM and EFTEM methods. Clusters of Au are observed along the surface of SiNWs and the existence of a thin Si film on gold particles capping the SiNWs is demonstrated. 相似文献
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E. Latu-Romain P. Gilet G. Feuillet P. Noel J. Garcia F. Lévy A. Chelnokov 《Microelectronics Journal》2009,40(2):224-228
We report on the integration and characterizations of vertically aligned ZnO nanowires (NWs). Technological processes have been developed both for mineral and organic planarizations with suitable morphologies. Optical and electrical characterizations of these integrated NWs have been performed. A comparison of the photoluminescence (PL) spectra at 300 K of the as-grown and integrated NWs has shown no significant impact of the integration process on the crystal quality of the NWs. Photoconducting properties in the UV-visible range have been investigated through collective electrical contacts. A small increase of resistivity in ZnO NWs under sub-bandgap illumination has been observed and discussed. The electrical transport properties of vertically integrated single NWs have also been investigated by scanning spread resistance microscopy (SSRM). Surface depletion layers in ZnO NWs have been evidenced. 相似文献
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Byungdon Min Jong Soo Lee Kyoungah Cho Ju Won Hwang Hyunsuk Kim Man Young Sung Sangsig Kim Jeunghee Park Hee Won Seo Seung Yong Bae Moon-Sook Lee Soon Oh Park Joo-Tae Moon 《Journal of Electronic Materials》2003,32(11):1344-1348
The GaN, GaP, InP, Si3N4, SiO2/Si, SiC, and ZnO semiconductor nanowires were synthesized by a variety of growth methods, and they were wrapped cylindrically
with amorphous aluminum oxide (Al2O3) shells. The Al2O3 was deposited on these seven different semiconductor nanowires by atomic layer deposition (ALD) at a substrate temperature
of 200°C using trimethylaluminum (TMA) and distilled water (H2O). Transmission electron microscopy (TEM) images taken for the nanowires revealed that Al2O3 cylindrical shells surround uniformly all these semiconductor nanowires. Our TEM study illustrates that the ALD of Al2O3 has an excellent capability to coat any semiconductor nanowires conformally; its coating capability is independent of the
chemical component, lattice structure, and growth direction of the nanowires. This study suggests that the ALD of Al2O3 on nanowires is one of the promising methods to prepare cylindrical dielectric shells in coaxially gated, nanowire field-effect
transistors (FETs). 相似文献
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We investigated by means of transmission electron microscopy (TEM) the final growth stage of GaAs/AlGaAs core-shell nanowires (NWs) self-assembled by Au-catalyst assisted metalorganic vapor phase epitaxy (MOVPE). TEM observations and energy dispersive x-ray spectroscopy revealed the presence of an AlGaAs tapered region of varying chemical composition nearby the NW extreme end (i.e. between the core-shell NW trunk and the Au nanoparticle catalyst). Our findings evidence that this region exhibits an unintentional AlyGa1−yAs/AlxGa1−xAs core-shell structure, a result of the combined axial (vapor-liquid-solid, VLS) self-assembly and conventional (vapor-solid, VS) overgrowth of the material. While the VS-grown AlxGa1−xAs alloy retains the Al composition (x=0.3) of the AlGaAs shell along the NW trunk, the central AlyGa1−yAs section is made of an Al-rich (y≈0.8–0.9) alloy segment formed during AlGaAs shell overgrowth, followed by a graded-alloy segment formed upon deposition of the terminating GaAs cap layer, the latter segment due to the effect of the Al reservoir left in the Au catalyst nanoparticle (NP). 相似文献
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Adam F. Hannon Wubin Bai Yi Ding Jonathan Winterstein Alfredo Alexander‐Katz J. Alexander Liddle Caroline A. Ross 《Advanced functional materials》2014,24(48):7689-7697
Transmission electron microscope (TEM) tomography was used to visualize the morphology and 3D connectivity of a lithographically templated, self‐assembled bilayer film of cylinder‐forming 45.5 kg/mol polystyrene‐block‐polydimethylsiloxane. The structure, formed after a 5 min solvothermal anneal, was imaged with a resolution of ≈3 nm in 3D, enabling a comparison between measurement and self‐consistent mean‐field theory (SCFT) calculations. Images of etched and unetched samples showed that etching collapsed the PDMS microdomain structure and reduced the template dimensions. In addition to the general comparison between modeled and measured dimensions, the tomography revealed connections between the orthogonal layers of cylinders at their crossing points. Comparison with the SCFT model, even under solvothermal annealing conditions, shows that it is helpful in understanding the detailed nanoscale structure of features created by directed self‐assembly (DSA), which is essential in developing nanomanufacturing processes based on DSA. 相似文献