RF磁控溅射和氮化法制备GaN纳米棒和纳米颗粒

利用射频磁控溅射法分别溅射ZnO中间层和Ga2O3薄膜到Si（111）衬底上，然后ZnO／Ga2O3薄膜在管式石英炉中常压下通氨气进行氨化，高温下ZnO在氨气气氛中被还原生成Zn而升华，而在不同的氨化时间下Ga2O3和氨气反应合成出GaN纳米棒和纳米颗粒。X射线衍射（XRD）测量结果表明，利用该方法制备GaN纳米棒和颗粒具有沿c轴择优取向生长的六方纤锌矿结构。利用扫描电子显微镜（SEM）、透射电子显微镜（TEM）、傅里叶红外透射谱（FTIR）及选区电子衍射（SAED）观测和分析了样品的形貌、成分和晶格结构。研究分析了此种方法合成GaN纳米结构的反应机制。     

RF偏置功率对磁控溅射AlN薄膜性能的影响北大核心

采用射频（RF）反应磁控溅射法,以氩气和氮气为反应气体,在不同的RF偏置功率下,在Si（100）和Si（111）衬底上制备了具有六方纤锌矿结构的AlN薄膜。使用扫描电子显微镜（SEM）表征了薄膜的截面形貌和厚度;利用原子力显微镜（AFM）和X射线衍射仪（XRD）研究了RF偏置功率对Si（111）和Si（100）衬底上沉积的AlN薄膜微观结构和表面粗糙度的影响。结果表明,在RF偏置功率为5~15 W时,两种衬底均可生长（002）择优取向AlN薄膜。RF偏置功率为20 W时,AlN薄膜（002）择优取向变弱,薄膜质量变差。当RF偏置功率为10 W时,Si（111）和Si（100）两种衬底沉积的AlN薄膜的半高宽（FWHM）值和表面均方根粗糙度均最小,其表面均方根粗糙度的最小值分别为2.427和2.836 nm。     

化学气相沉积可控制备超薄二维MoS_2纳米片

采用化学气相沉积(CVD)技术,以硫粉和MoO_3为反应剂、氩气为载气,在SiO_2/Si衬底上制备超薄二维MoS_2纳米片。采用扫描电子显微镜(SEM)、原子力显微镜(AFM)、透射电子显微镜(TEM)、喇曼光谱和光致发光光谱测试分析技术,研究硫粉送入距离对超薄MoS_2纳米片的形貌、结构和光学性质的影响规律。结果表明:硫粉送入距离为17～25 cm时,距离MoO_31 cm的SiO_2/Si衬底上形成平行于衬底生长的二维MoS_2纳米片;硫粉送入距离为25～29 cm时,MoO_3正上方的SiO_2/Si衬底上形成竖直排列的二维MoS_2纳米片。通过调控硫粉送入距离和衬底的位置可以控制MoS_2的形成过程,实现水平排列和垂直排列二维MoS_2纳米片的可控生长。     

衬底退火温度对ZnO纳米结构形貌和发光特性的影响

利用热蒸发Zn粉的方法,在Au/掺铝氧化锌(AZO) /石英衬底上生长ZnO纳米结构。为了研究不同 温度退火后的衬底对生长的ZnO纳米结构的影响,Au/AZO/石英衬底在生长纳米结构前分别在 300、500和700℃真空下退火。Au/AZO/石英衬底的表面形貌用原子力显微镜(AFM)观测 。ZnO纳米结构的微结构、形貌和 光学性能分别用X射线衍射(XRD)、扫描电子显微镜(SEM)、透射电子显微镜(TEM)和荧光光 谱仪进行测量。结果表明,在未退火和300 ℃ 退火衬底上生长了大量的ZnO纳米棒,而在500℃退火衬底上沉积了大量ZnO纳米颗粒。单晶结构 的纳米棒的平均直径分别约50nm,其 生长机制为蒸气-液体-固体(VLS)生长机制。荧光光谱显示所有的样品 都存在紫外发光峰和深能级发射带,随着退火温度的升高,生长的纳米结构的紫外发光峰相 对强度增强,而深能级发射强度减弱。     

碳纳米球薄膜的场发射特性

利用微波等离子体化学气相沉积法,在Si(100)衬底上制备了碳纳米球薄膜。利用拉曼光谱和场发射扫描电子显微镜研究了薄膜的结构以及表面形貌,表明碳纳米球薄膜是由约2～3μm长、100nm宽的无定形碳纳米片相互缠绕、交织成球状而构成的。在高真空系统中测量了碳纳米球薄膜的场发射特性,结果表明,碳纳米球薄膜具有良好的场发射特性,阈值电场为3.1V/μm,当电场增加到10V/μm时,薄膜的场发射电流密度可达到60.7mA/cm2。通过三区域电场模型合理地解释了碳纳米球薄膜在低电场、中间电场和高电场区域的场发射特性。     

ZnO纳米晶须的形态控制及其结构表征

采用激光分子束外延法先在Si(111)衬底上制备Zn薄膜,在不同的氧气体积流量和生长温度下,用热蒸发法在镀有Zn薄膜的Si(111)衬底上制备了不同形貌的ZnO纳米晶须。分别用X射线衍射(XRD)、扫描电子显微镜(SEM)、透射电子显微镜(TEM)和高分辨透射电子显微镜(HRTEM)对样品的成分、微结构和形貌进行了表征。Zn薄膜在高温下被氧化,并为晶体生长提供均匀的成核点,有利于形成一定大小和数量的ZnO晶核。研究结果表明,氧气体积流量和生长温度对ZnO纳米晶须的形貌有一定的影响。     

TiO2薄膜的热处理晶化及形貌研究

对Si(111)和Si(100)衬底上用化学气相沉积法制成的TiO2薄膜进行了不同温度的热处理，并用原子力显微镜对处理后薄膜的形貌变化进行了观察。X－射线衍射分析表明形貌变化过程即晶化过程。晶化物相为金红石。晶化程度（或形貌变化程度）与热处理的温度有次数（或热处理时间）有关。Si(111)衬底上TiO2晶化形貌为杂乱分布的柱状、板状，定向不好；而Si(100）衬底上TiO2晶化形貌为定向较好的四方柱状或板状，这是因为Si(100)与金红石（001）都属四方对称结构，两相结构在此方向上容易匹配的结果。在相同热处理条件下，Si(111)衬底比Si(100)衬底上TiO2晶化程度高，说明非定向附生的晶化作用比定向附生的晶化作用容易实现。     

Cu/Ta/SiO_2/Si多层膜纳米压痕与压痕下微观结构的研究

Cu/Ta/SiO2/Si多层膜结构是目前集成电路制造工艺中的常见结构,其硬度与弹性模量通过纳米压入技术测得。为了表征纳米压痕下的形变微观区域,采用聚焦离子束加工出压痕截面,同时进行扫描电子、扫描离子显微观察,发现样品衬底发生开裂,多层膜结构出现分层现象。TEM分析表明分层出现在Ta/SiO2界面,说明这是该结构的一个薄弱环节。     

基于岛状多晶氧化锌薄膜的电泵浦紫外随机激光

光电子集成是当前光电技术和信息工程领域的新趋势和研究热点，其中光源集成化和工艺相容性已成为制约其进一步发展和应用的关键问题。报道了一种设计简单的、可直接集成在硅衬底上面的激子型激光二极管器件和工艺。基于岛状多晶氧化锌薄膜构建了一个金属/绝缘体/半导体（Au/MgO/ZnO MIS）异质结器件。利用Si衬底与ZnO外延层之间天然的大晶格失配，诱导ZnO薄膜表面形成了高度无序的多晶岛状纳米结构，从而在异质结激活层（ZnO/MgO界面区域）形成了高度无序的折射率随空间变化的散射介质。这极大增强了光学散射，有利于获得低阈值的随机激射。文中这种简单的光源器件结构设计和制备工艺提供了一种自下而上的实现氧化锌基集成光电子器件的新思路。     

纳米6H-SiC薄膜的等离子体化学气相沉积及其紫外发光

采用螺旋波等离子体化学气相沉积技术在Si(100)衬底上制备了具有纳米结构的碳化硅(SiC)薄膜.通过X射线衍射、傅里叶红外吸收和扫描电子显微镜等技术对所制备薄膜的结构、形貌以及键合特性进行了分析,利用光致发光技术研究了样品的发光特性.分析表明,在500℃的衬底温度和高氢气稀释条件下,所制备的纳米SiC薄膜红外吸收谱主要表现为SiC TO声子吸收,X射线衍射显示所制备的纳米SiC薄膜为6H结构.采用氙灯作为激发光源,不同氢气流量下所制备的样品在室温下呈现出峰值波长可变的紫外发光.     

Hydrothermal synthesis of SnO2 nanocorals,nanofragments and nanograss and their formaldehyde gas-sensing properties

Morphology plays an important role in the properties of nanomaterials. We successfully synthesized three new SnO₂ morphologies, nanocorals, nanofragments and nanograss, via a simple hydrothermal method with surfactant additives. The final products were characterized by field-emission scanning electron microscopy and X-ray diffraction. We found that the surfactants played a critical role in the synthesis of different SnO₂ nanostructures. In particular, when poly(ethylene glycol) was added as a surfactant, a unique grass-like structure was obtained. The mechanism of formation for this novel structure is discussed. The gas-sensing performance of all the products was investigated. The results show that the nanograss morphology had a superior gas response to formaldehyde than the other morphologies.     

纳米光子学材料漫谈

评述纳米光子学材料的制备.纳米光子学材料的种类繁多,不同的纳米形态、结构具有不同的特性,其制备方法更是成千上万种.列举20种形态的纳米光子学材料,阐明它们的制备方法、特性和应用前景.     

Temperature‐Controlled Catalytic Growth of ZnS Nanostructures by the Evaporation of ZnS Nanopowders

ZnS nanostructures with different morphologies, sizes, and microstructures were synthesized by the evaporation of ZnS nanopowders. Based on the appearance of the as‐synthesized products, we show that substrate temperature and catalyst are the critical factors for controlling the size and the structure of various kinds of ZnS nanostructures, such as nanorods, nanowires, nanobelts, and nanosheets. Within a certain temperature range, products with a specific morphology can be obtained. Therefore, it may be possible to obtain ZnS nanostructures with a specific morphology by controlling the reaction temperature and catalyst. This represents an important step toward the design and control of nanostructures. High‐resolution electron microscopy revealed that most of the nanorods and nanowires grew along the [100] direction, whereas most of the nanobelts and nanosheets grew along [001]. Photoluminescence properties and growth mechanisms of these as‐synthesized ZnS nanostructures are discussed.     

ZnSe纳米材料及界面的制备与表征

利用热蒸发法对ZnSe纳米材料的相控合成进行了研究,制备了多种具有稳定闪锌矿和亚稳纤锌矿结构的ZnSe纳米材料,如ZnSe纳米线、纳米圈、纳米轮及三晶纳米带。同时,在相控合成基础上,通过改变管式炉内反应压强获得了几种同质与异质界面。利用多种透射电子显微学手段对合成的ZnSe纳米材料及相关同质与异质界面进行了深入表征,并对ZnSe纳米材料的生长机理进行了探讨。     

The Role of Sulfur in the Synthesis of Novel Carbon Morphologies: From Covalent Y‐Junctions to Sea‐Urchin‐Like Structures

A detailed characterization, using high resolution electron microscopy/microanalysis (SEM, TEM, HRTEM, and EDX), reveals tubular carbon nanostructures exhibiting complex and fascinating morphologies. The materials were obtained by sulfur‐assisted chemical vapor deposition. It is demonstrated that S not only acts on the catalyst, but also can be detected in the carbon lattice of the nanostructures. The experimental data presented here confirms the critical role of S, which is responsible for inducing curvature and therefore influencing the final carbon nanostructure morphology. In particular, different types of covalent Y‐junctions of CNTs and even sea urchin‐like nanostructures were produced and their experimental conditions are listed and discussed.     

控制定向聚集水热合成制备多种形貌的纳米钛酸锶

通过聚乙烯醇（PVA）辅助的水热合成方法制备出了纳米钛酸锶（SrTiO3）材料。X射线衍射（XRD）证明其结构为立方钙钛矿结构;透射电子显微镜（TEM）观察显示通过控制原料中锶和钛的浓度可以控制合成出具有花状纳米结构、纳米线及纳米线网状结构形貌的纳米SrTiO3材料。选区电子衍射（SAED）和高分辨透射电镜（HRTEM）证明不同形貌的纳米SrTiO3为类单晶结构。研究结果表明反应物中锶和钛的浓度是控制定向聚集合成不同形貌纳米SrTiO3结构的主要因素。     

Nanomaterials via Laser Ablation/Irradiation in Liquid: A Review

Laser ablation of solid targets in the liquid medium can be realized to fabricate nanostructures with various compositions (metals, alloys, oxides, carbides, hydroxides, etc.) and morphologies (nanoparticles, nanocubes, nanorods, nanocomposites, etc.). At the same time, the post laser irradiation of suspended nanomaterials can be applied to further modify their size, shape, and composition. Such fabrication and modification of nanomaterials in liquid based on laser irradiation has become a rapidly growing field. Compared to other, typically chemical, methods, laser ablation/irradiation in liquid (LAL) is a simple and “green” technique that normally operates in water or organic liquids under ambient conditions. Recently, the LAL has been elaborately developed to prepare a series of nanomaterials with special morphologies, microstructures and phases, and to achieve one‐step formation of various functionalized nanostructures in the pursuit of novel properties and applications in optics, display, detection, and biological fields. The formation mechanisms and synthetic strategies based on LAL are systematically analyzed and the reported nanostructures derived from the unique characteristics of LAL are highlighted along with a review of their applications and future challenges.     

Selective Atmospheric Pressure Chemical Vapor Deposition Route to CdS Arrays,Nanowires, and Nanocombs

CdS arrays, nanowires, and nanocombs were selectively prepared through an atmospheric pressure chemical vapor deposition (APCVD) process with CdCl₂ and S as sources. The morphologies could be controlled by adjusting the deposition position, the temperature, and the flux of the carrier gas. The phase structure, morphologies, and photoluminescence properties of the CdS products were investigated by X‐ray diffraction (XRD), scanning electron microscopy (SEM), high‐resolution transmission electron microscopy (HRTEM), and photoluminescence (PL) spectra. The formation mechanism of the nanowires is discussed on the basis of the experimental results. The adopted synthetic route is expected to be applied in the synthesis of other metal sulfide one‐dimensional (1D) nanostructures.     

Synthesis and photoluminescence properties of wash-board belt-like ZnSe nanostructures

Washboard belt-like zinc selenide （ZnSe） nanostructures are successfully prepared by a simple chemical vapor deposi- tion （CVD） technology without catalyst. The phase compositions, morphologies and optical properties of the nanos- tructures are investigated by X-ray diffraction （XRD）, scanning electron microscopy （SEM）, high-resolution transmis- sion electron microscopy （HRTEM） and photoluminescence （PL） spectroscop, respectively. A vapor-liquid mecha- nism is proposed for the formation of ZnSe belt-like structures. Strong PL from the ZnSe nanostructure can be tuned from 462 nm to 440 nm with temperature varying from 1000 ℃ to 1200 ℃, and it is demonstrated that the washboard belt-like ZnSe nanostructures have potential applications in optical and sensory nanotechnology. This method is ex- pected to be applied to the synthesis of other II-VI groups or other group＇s semiconducting materials.     

纳米级性能微测量中的原位透射电子显微学的现状和展望

纳米材料的研究无论是在基础科学还是在应用技术上都面临着许多新的挑战。纳米材料的性能极大地取决于它们的尺寸和形状。测量大面积或大量的纳米材料所得的性能是整个样品的平均值，因此，单个纳米颗粒或单根纳米管的不寻常的特性就被掩盖了。测量由原子结构所决定的单一纳米结构的性能是纳米科学的一个基本方向。对现有的测试技术和试验方法来说，表征单一纳米颗粒／纳米管／纳米纤维的性能是一难题。首先，因为它的尺寸（直径和长