水热法制备氧化锌阵列及其形貌控制

低温条件下, 采用水热法, 通过控制前驱溶液的pH值, 在预先镀有ZnO纳米膜的导电玻璃衬底上制备了形貌各异的ZnO阵列, 用X射线衍射(XRD)、扫描电子显微镜(SEM)、透射电子显微镜(TEM)、高分辨透射电子显微镜(HRTEM)和紫外-可见分光光度计等分析手段对ZnO纳米棒的结构和形貌进行了表征. 同时还对不同形貌阵列的形成机理进行探讨. 结果表明, 所制ZnO纳米棒为单晶, 沿c轴择优生长. 在pH值为10.5左右时, 能得到取向性好、直径均匀(d~nm)的ZnO纳米棒阵列. 光学测试表明, 在可见光区透光度超过80%, 禁带宽度约为3.25eV.     

扩散诱导的锌间隙相关施主缺陷对ZnO纳米棒结构及光电特性的影响

采用射频磁控溅射技术和水浴法在SiO2单晶衬底上生长了Zn纳米颗粒/ZnO纳米棒复合材料(Zn/ZnO)。后期热处理促使Zn/ZnO界面之间发生元素相互扩散,直接向ZnO纳米棒中引入额外锌杂质,从而获得了富锌的ZnO纳米棒材料。借助扫描电子显微镜、X射线衍射仪、霍尔测试仪、分光光度计和拉曼光谱仪研究了富锌ZnO纳米棒的形貌、结构以及光电特性。结果表明,所有ZnO纳米棒均呈整齐的六角纤锌矿结构,相比ZnO纳米棒,富锌纳米棒具有相对较差的结晶质量,较好的导电性,较低的透射率和较窄的禁带宽度。拉曼光谱研究表明,通过扩散法向ZnO纳米棒引入的锌间隙相关施主缺陷,是其拉曼光谱中出现异常的275 cm^-1振动模的来源,也是导致富锌ZnO纳米棒微结构以及光电特性显著变化的主要原因。     

Au修饰ZnO纳米棒的制备及紫外探测性能研究

采用磁控溅射技术和水热法制备金(Au)纳米颗粒修饰的氧化锌(ZnO)纳米棒材料。利用场发射扫描电子显微镜、透射电子显微镜、X射线衍射仪和荧光光谱仪等测试设备对不同溅射功率下的Au纳米颗粒修饰的ZnO纳米棒进行了表征分析。实验结果表明,不同溅射功率下的ZnO纳米棒均呈六方纤锌矿结构,沿晶面(002)择优生长,具有较高的结晶度;修饰后ZnO纳米棒表面附着Au纳米颗粒,能有效增强其紫外光激发强度;当射频溅射功率为80 W时,ZnO纳米棒表现出最佳的紫外探测性能,相比于未修饰的ZnO纳米棒,Au纳米颗粒能抑制ZnO纳米棒的持续光电导(PPC)效应,其紫外探测的响应/恢复时间分别降低了6.05和4.54 s,光暗电流比由9.31提升至32.40,光响应度达到1.94A/W,显著增强了ZnO纳米棒紫外探测的能力。     

生长温度对热蒸发法制备ZnO纳米线的结构与发光性能影响

采用无金属催化剂的简单热蒸发法,在Si(100)衬底上不同生长温度下成功地制备了高密度和大长径比的单晶ZnO纳米线。分别利用X射线衍射仪(XRD)、扫描电子显微镜(SEM-EDS)、透射电子显微镜(TEM)及荧光光谱仪表征样品的结构和发光性质。XRD和TEM研究表明,所制备的样品为沿c轴择优取向生长的单晶ZnO纳米线,具有六方纤锌矿结构。SEM和TEM研究表明,生长温度对ZnO纳米线的形貌及长径比的影响较大。当生长温度为700℃时,制备得到长径比为300(长度约为15μm,直径约为50nm)的ZnO纳米线;低于600℃时,形成花状ZnO纳米锥或纳米棒;高于700℃时,形成小长径比的ZnO纳米棒。此外,室温光致发光(PL)谱上出现一个强而尖锐的紫外发射峰以及一个弱而宽泛的蓝光发射峰。采用的热蒸发法制备ZnO纳米线基于气-固(VS)生长机理且该生长方法可用于大规模、低成本制备高纯度的单晶ZnO纳米材料。     

后续的KOH腐蚀对ZnO纳米棒阵列及性能的影响

采用化学沉积和KOH腐蚀结合的方法,在FTO导电玻璃上制备了ZnO纳米棒阵列。用XRD、SEM、I-V曲线对ZnO纳米棒阵列的结构和性能进行了表征。结果表明:ZnO纳米棒为单晶,属于六方纤锌矿结构。后续的KOH腐蚀有利于ZnO纳米阵列形貌的改变及光电性能的提高,将ZnO纳米棒阵列作为光阳极制备染料敏化太阳能电池,被KOH腐蚀后的ZnO纳米棒阵列的光电转换效率(η)、短路电流(Jsc)、开路电压(Voc)分别达到1.2%、0.006A/cm2、0.557V,与未被KOH腐蚀的ZnO纳米棒相比,光电转换效率提高了1.05%。     

ZnO纳米棒水热法制备及其发光性能

采用水热法在玻璃基底上成功制备出了ZnO纳米棒.用x射线衍射仪(xRD)和扫描电子显微镜(SEM)对ZnO纳米棒的晶体结构和表面形貌进行了表征,初步探讨了ZnO纳米棒的生长机理;同时对ZnO纳米棒的光致发光性能进行测量,分析了水热温度和反应时间对ZnO纳米棒光致发光性能的影响.结果表明:ZnO纳米棒呈现六方纤锌矿结构,具有沿(002)晶面择优生长特征;随着水热反应温度的升高,ZnO纳米棒的发光强度逐渐增强;随着反应时间的延长,ZnO纳米棒发光强度在1～3 h内增强,而在3～10 h反而减弱.     

ZnO纳米棒阵列膜的制备及其光电化学性能研究

采用化学溶液沉积法,在ZnO纳米颗粒膜修饰的FTO导电玻璃基底上,制备了ZnO纳米棒阵列。用X射线衍射仪（XRD）、场发射扫描电子显微镜（FESEM）、透射电子显微镜（TEM）对样品进行表征。研究结果表明所制备的ZnO纳米棒为六方纤锌矿相单晶结构,沿c轴择优取向生长,平均直径约为40nm,长度约为900nm;ZnO纳米棒阵列生长致密,取向性较一致。以曙红Y敏化的ZnO纳米棒阵列膜为光阳极制作了染料敏化太阳能电池原型器件,在光照强度为100mW/cm2下,其开路电压为0.418V,短路电流为0.889mA/cm2,总的光电转换效率为0.133%。     

生长温度对热蒸发法制备ZnO纳米线的结构与发光性能影响

采用无金属催化剂的简单热蒸发法,在Si(100)衬底上不同生长温度下成功地制备了高密度和大长径比的单晶ZnO纳米线。分别利用X射线衍射仪(XRD)、扫描电子显微镜(SEM-EDS)、透射电子显微镜(TEM)及荧光光谱仪表征样品的结构和发光性质。XRD和TEM研究表明,所制备的样品为沿C轴择优取向生长的单晶ZnO纳米线,具有六方纤锌矿结构。SEM和TEM研究表明,生长温度对ZnO纳米线的形貌及长径比的影响较大。当生长温度为700℃时,制备得到长径比为300(长度约为15μm,直径约为50nm)的ZnO纳米线。低于600℃时,形成花状ZnO纳米锥或 纳 米 棒。高 于700℃时,形 成 小 长 径 比 的ZnO纳米棒。此外,室温光致发光(PL)谱上出现一个强而尖锐的紫外发射峰以及一个弱而宽泛的蓝光发射峰。采用的热蒸发法制备ZnO纳米线基于气-固(VS)生长机理且该生长方法可用于大规模、低成本制备高纯度的单晶ZnO纳米材料。     

低温化学法合成单晶氧化锌纳米带

用低温化学溶液法在100℃制备了非层状结构的单晶ZnO纳米带。在反应初期先形成层状结构的碱式醋酸锌(Zn(OH)_(2-x)(CH_3COO)_x nH_2O)前驱体,然后在水热条件下使其转化成单晶ZnO纳米带。用透射电子显微镜(TEM)、场发射扫描电子显微镜(FESEM)、X射线衍射(XRD)、高分辨透射电子显微镜(HRTEM)和荧光光谱(PL)对ZnO纳米带的形态、结构和光学性质进行了表征.结果表明,在上述反应中醋酸根阴离子和弱有机碱六次甲基四胺(HMT)对前驱体和ZnO纳米带的形成起了关键作用。     

ZnO棒晶阵列薄膜的水溶液法生长

采用低温水溶液法, 在涂覆ZnO种子层的ITO基底上制备了高度取向的ZnO棒晶阵列, 考察了棒晶的生长过程以及生长液浓度、生长时间对薄膜形貌的影响. 用扫描电子显微镜(SEM),X射线衍射(XRD), 场发射扫描显微镜(FESEM)以及高分辨透射电镜(HRTEM)对ZnO纳米棒的结构和形貌进行了表征. 结果表明, ZnO薄膜的形貌强烈依赖于生长溶液的浓度和生长时间, ZnO棒是单晶, 属于六方纤锌矿结构, 具有沿(002)晶面择优生长的特征, 生长方式为层层台阶生长, 反应时间达到48h后, 通过二次生长形成特殊的板状晶.     

Growth of aligned hexagonal ZnO nanorods on FTO substrate for dye-sensitized solar cells (DSSCs) application

This article reports a facile growth of well-crystalline aligned hexagonal ZnO nanorods on fluorine-doped tin-oxide (FTO) substrate via non-catalytic thermal evaporation process. The morphological investigations done by field-emission scanning electron microscope (FESEM) and transmission electron microscopy (TEM) reveal that the grown products are aligned hexagonal ZnO nanorods which are grown in a very high density over the whole substrate surface. The detailed structural properties observed by high-resolution TEM equipped with selected area electron diffraction (SAED) and X-ray diffraction (XRD) pattern confirmed that the synthesized nanorods are well-crystalline possessing wurtzite hexagonal phase and preferentially grown along the c-axis direction. A sharp and strong UV emission at 381 nm in room-temperature photoluminescence (PL) spectrum showed that the as-grown ZnO nanorods possess excellent optical properties. The as-grown nanorods were used as photo-anode for the fabrication of dye-sensitized solar cells (DSSCs) which exhibits an overall light-to-electricity conversion efficiency (ECE) of 0.7% with V(oc) of 0.571 V, J(sc) of 2.02 mA/cm2 and FF of 0.58.     

Morphological transformations induced by Co impurity in ZnO nanostructures prepared by rf-sputtering and their physical properties

Growth of uniform and vertically well aligned nanorods is a difficult process and becomes more complicated in case of ZnO nanorods on silicon (Si) substrate due to thermal instability of the Si substrate and large lattice mismatch (~?40%) between the substrate and the ZnO nanorods array. Growth of ZnO nanorods assisted by metal ion via rf-sputtering is a good technique; however, it needs many parameters to be controlled for desired growth and morphology of nanostructures. In this work, we report the morphological transformations of ZnO nanostructured thin film by simply controlling the concentration of Cobalt (Co) impurity in sputtering target. With the introduction of Co ions in ZnO matrix, the initial coalescence grain structure (pyramidal morphology) changes into columnar grains and as the concentration of Co ions increases further, a highly oriented ZnO nanorods array is obtained. The possible mechanism with the help of schematic diagram is also proposed for the morphological transformation of ZnO nanostructures. The vertically aligned nanorods show good optical properties as well as robust ferromagnetism at room temperatures. It has also been observed that with the dopant conc. increasing there was a significant decrease in the band gap energy. The structure and morphology of rf-sputtered nanostructured thin films were investigated by X-ray diffraction, field emission scanning electron microscopy, transmission electron microscopy and selected area electron diffraction. Interestingly, with Co conc. increasing in ZnO matrix results in decreasing LO modes in Raman spectroscopy. It can have strong influence on the magnetic properties of the material. The good optical and strong ferromagnetic properties of the ZnO nanorods, suggest its possible applications in the fields of lasers, spintronics and medical applications.     

Surfactant mediated growth of ZnO nanostructures and their dye sensitized solar cell properties

Single crystalline and highly aligned ZnO nanorods, faceted microrods, nanoneedles and nanotowers were grown onto glass substrates by a facile aqueous chemical method at relatively low temperature (90 °C). Various structure directing agents or organic surfactants such as diaminopropane (DAP), polyacrylic acid (PAA) and polyethylenimine (PEI) were used to modify the surface morphology. The samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and optical absorption. It was found that, vertically aligned ZnO nanorods formation takes place with preferential orientation along (002) plane. The organic surfactants play an important role in modifying the morphology. The samples were further used to fabricate dye sensitized solar cells. The highest photocurrent (670 μA) and efficiency were observed for the ZnO:PEI sample.     

Sonochemical method for the preparation of ZnO nanorods and trigonal-shaped ultrafine particles

ZnO nanorods and trigonal-shaped ZnO ultrafine particles were synthesized by sonochemical method through the decomposition of zinc acetate dihydrate in paraffin oil. ZnO nanorods and trigonal-shaped ZnO ultrafine particles were characterized by powder X-ray diffraction (XRD), transmission electron microscopy (TEM), selected area electron diffraction (SAED), scanning electron microscopy (SEM), and UV–visible spectrophotometer. One strong UV emission peak at 390 nm was observed.     

Vapor growth and photoconductivity of single-crystal nickel-phthalocyanine nanorods

Nickel-phthalocyanines (NiPc) with planar aromatic structures are ideal building blocks for organic nanostructures. They can self-assemble into stacks through π-π interaction, exhibit high thermal and chemical stabilities, and possess outstanding electrical and optical properties. Herein, single-crystal NiPc nanorods were synthesized by a facile vapor transfer deposition method. Their nanostructures and compositions were investigated by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), and Fourier-transform infrared (FTIR) in detail. The deposited NiPc nanorods were found to be the β-phase single crystals. Moreover, the NiPc nanorod-based devices were fabricated and exhibited high photocurrent upon white-light illumination. This indicates that the NiPc nanorods can be considered as a candidate material for fabricating photoelectric devices.     

Defect induced room temperature ferromagnetism in well-aligned ZnO nanorods grown on Si (100) substrate

In this work, we report the fabrication of high quality single-crystalline ZnO nanorod arrays which were grown on the silicon (Si) substrate using a microwave assisted solution method. The as grown nanorods were characterized using X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), photo-luminescence (PL) and magnetization measurements. The XRD results indicated that the ZnO nanorods are well oriented with the c-axis perpendicular to the substrate and have single phase nature with the wurtzite structure. FE-SEM results showed that the length and diameter of the well aligned rods is about ~ 1 μm and ~ 100 nm respectively, having aspect ratio of 20-30. Room-temperature PL spectrum of the as-grown ZnO nanorods reveals a near-band-edge (NBE) emission peak and defect induced green light emission. The green light emission band at ~ 583 nm might be attributed to surface oxygen vacancies or defects. Magnetization measurements show that the ZnO nanorods exhibit room temperature ferromagnetism which may result due to the presence of defects in the ZnO nanorods.     

Fabrication of vertically aligned ultrafine ZnO nanorods using metal-organic vapor phase epitaxy with a two-temperature growth method

We report the fabrication of vertically aligned ultrafine ZnO nanorods using metal-organic vapor phase epitaxy and applying a two-temperature growth method. First, thick nanorods were grown vertically on the substrate at a lower temperature. Then, ultrafine ZnO nanorods with an average diameter of 17.7?nm were grown from the tips of the thick nanorods at a higher temperature. The direction of the ultrafine ZnO nanorods followed that of the preformed vertically aligned thick nanorods. Electron microscopy revealed that the ultrafine nanorods were single crystals and the growth direction was along the c axis. Excellent photoluminescence characteristics of the nanorods were confirmed.     

Effects of temperature on ZnO hybrids grown by metal-organic chemical vapor deposition

The growth of three-dimensional ZnO hybrid structures by metal-organic chemical vapor deposition was controlled through their growth pressure and temperature. Vertically aligned ZnO nanorods were grown on c-plane of sapphire substrate at 600 °C and 400 Torr. ZnO film was then formed in situ on the ZnO nanorods at 100, 600, and 700 °C and 10 Torr. High-resolution X-ray diffraction measurements showed that the ZnO film on the nanorods/sapphire grew epitaxially, and that the ZnO film/nanorods hybrid structures had well-ordered wurtzite structures. The hybrid ZnO structure was shown to be about 3–5 μm by field-emission scanning electron microscopy. The hybrid formed at 600 °C showed better crystalline quality those formed at 100 °C or 700 °C. These structures have potential applicability as nanobuilding blocks in nanodevices.     

Synthesis and photoluminescence properties of aligned Zn2GeO4 coated ZnO nanorods and Ge doped ZnO nanocombs

Aligned Zn₂GeO₄ coated ZnO nanorods and Ge doped ZnO nanocombs were synthesized on a silicon substrate by a simple thermal evaporation method. The structure and morphology of the as-synthesized nanostructure were characterized using scanning electron microscopy and transmission electron microscopy. The growth of aligned Zn₂GeO₄ coated ZnO nanorods and Ge doped ZnO nanocombs follows a vapor-solid (VS) process. Photoluminescence properties were also investigated at room temperature. The photoluminescence spectrum reveals the nanostructures have a sharp ultraviolet luminescence peak centered at 382 nm and a broad green luminescence peak centered at about 494 nm.     

Morphology control of 1D ZnO nanostructures grown by metal-organic chemical vapor deposition

The morphology of ZnO nanostructures grown by metal-organic chemical vapor deposition under various growth conditions was examined by scanning electron microscopy. An increase in the growth temperature resulted in the formation of 1D nanostructures with diameters decreasing with increasing temperature. Vertically aligned nanorods with a needle-like tip shape were grown on a previously deposited homo-seed layer. Also the seed layer reduced the growth temperature of 1D nanorods. Low-temperature growth posterior to nanorod growth resulted in the formation of nanorods with an inverted graded diameter.