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Zn/O ratio and oxygen chemical state of nanocrystalline ZnO films grown at different temperatures 下载免费PDF全文
ZnO nanocrystalline films are prepared on Si substrates at different temperatures by using metal-organic chemical vapour deposition (MOCVD). It is observed that when the growth temperature is low, the stoichiometric ratio between Zn and O atoms has a large deviation from the ideal ratio of 1:1. The ZnO grains in the film have small sizes and are not well crystallized, resulting in a poor photoluminescence (PL) property. When the temperature is increased to an appropriate value, the Zn/O ratio becomes optimized, and most of Zn and O atoms are combined into Zn-O bonds. Then the film has good crystal quality and good PL property. If the temperature is fairly high, the interfacial mutual diffusion of atoms between the substrate and the epitaxial film appears, and the desorption process of the oxygen atoms is enhanced. However, it has no effect on the film property. The film still has the best crystal quality and PL property. 相似文献
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利用水热法制备出与透明导电衬底附着良好的多种纳米结构ZnO薄膜,包括纳米柱阵列、纳米管阵列、纳米片阵列等,方便集成在多种器件上。并且实现了阵列中纳米柱、纳米管外径的调节,柱外径在50~300 nm范围内可调,管外径在300~1 000 nm范围内可调。几种纳米薄膜均显示出较强的疏水性。在未经任何低表面能物质修饰的情况下,水在外径约300 nm的管状阵列表面的静态接触角已达138°。而在紫外光照射下,这些疏水的ZnO薄膜还可以变得亲水。这些研究结果为ZnO纳米阵列在相关方面的应用提供了重要依据。 相似文献
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A Simple Route of Morphology Control and Structural and Optical Properties of ZnO Grown by Metal-Organic Chemical Vapour Deposition 下载免费PDF全文
Employing the metal-organic chemical vapour deposition (MOCVD) technique, we prepare ZnO samples with different morphologies from the film to nanorods through conveniently changing the bubbled diethylzinc flux (BDF) and the carrier gas flux of oxygen (OCGF). The scanning electron microscope images indicate that small BDF and OCGF induce two-dimensional growth while the large ones avail quasi-one-dimensional growth. X-ray diffraction (XRD) and Raman scattering analyses show that all of the morphology-dependent ZnO samples are of high crystal quality with a c-axis orientation. From the precise shifts of the 20 locations of ZnQ (002) face in the XRD patterns and the E2 (high) locations in the Raman spectra, we deduce that the compressive stress forms in the ZnO samples and is strengthened with the increasing BDF and OCGF. Photoluminescence spectroscopy results show all the samples have a sharp ultraviolet luminescent band without any defects-related emission. Upon the experiments a possible growth mechanism is proposed. 相似文献
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Zn/O ratio and oxygen chemical state of nanocrystalline ZnO films grown at different temperatures 下载免费PDF全文
ZnO nanocrystalline films are prepared on Si substrates at different temperatures by using metal-organic chemical vapour deposition(MOCVD).It is observed that when the growth temperature is low,the stoichiometric ratio between Zn and O atoms has a large deviation from the ideal ratio of 1:1.The ZnO grains in the film have small sizes and are not well crystallized,resulting in a poor photoluminescence(PL) property.When the temperature is increased to an appropriate value,the Zn/O ratio becomes optimized,and most of Zn and O atoms are combined into Zn-O bonds.Then the film has good crystal quality and good PL property.If the temperature is fairly high,the interfacial mutual diffusion of atoms between the substrate and the epitaxial film appears,and the desorption process of the oxygen atoms is enhanced.However,it has no effect on the film property.The film still has the best crystal quality and PL property. 相似文献
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本文研究了在金属有机化学气相沉积法(MOCVD)生长过程中,锌(Zn)源和氧(O)源载气流量的改变对ZnO纳米棒阵列的影响.通过改变源材料载气的流量,得到了直径从150 nm到20 nm范围、均一性明显改善的ZnO纳米棒.采用扫描电子显微镜(SEM),X射线衍射图谱(XRD),拉曼光谱(Raman)和光致荧光光谱(PL)等测试手段对样品的形貌结构和光学特性进行了表征.SEM和XRD结果表明当Zn源和O源的载气流量均为1 SLM时,所得的纳米棒直径最均匀,排列整齐,垂直于衬底生长,且结晶度最好.PL谱显示纳米棒的紫外带边峰发生了蓝移,可能与表面效应的增加有关. 相似文献
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通过在聚酰亚胺(PI)中分别添加笼型八氨基苯基硅倍半氧烷(OAPS)、笼型八苯基硅倍半氧烷(OPS)、梯形聚苯基硅倍半氧烷(PPSQ)和无机纳米SiO2,制备了4种含硅聚酰亚胺(PI/Si)复合膜. 对PI/Si复合膜的相容性、力学性能、热性能和阻燃性能进行了研究. 结果表明,OAPS与PI间展现出较好的相容性,PPSQ次之,而OPS,SiO2与PI的相容性较差;但相容性与复合膜的力学和热性能无明显的对应关系. SiO2可提高PI的力学性能;PI/OAPS复合膜的Tg最高;OAPS,PPSQ或SiO2的加入使PI复合膜的热稳定性稍有提高,而少量OPS的加入大大降低PI膜的热稳定性. 这类PI/Si复合膜的显著特点是能够大幅提高PI膜的极限氧指数,含硅化合物能够增加PI燃烧后残炭量,使残炭的形貌得到显著改善. PI/Si复合膜在燃烧过程中在表面形成一层白色含硅包裹层,起到隔热隔氧及保护内层有机物不被燃烧的作用. 硅倍半氧烷对炭层形貌的改善显著,展现出比SiO2更好的阻燃性能. 相似文献
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使用高效液相色谱-电喷雾四级杆飞行时间质谱(HPLC-ESI-Q-TOF MS)联用技术对八硝基苯基硅倍半氧烷(ONPS)纯度进行分析, 从而判定ONPS产物峰及杂质峰的位置, 根据ONPS峰和杂质峰的面积比计算ONPS的纯度. 通过改变HPLC的洗脱梯度和测试时间, 将ONPS产物中的杂质峰完全分开, 测得硝基苯基硅倍半氧烷(NPS)质量分数为97.55%, 其中ONPS的纯度约为92.42%, 产物中含有九硝基八苯基硅倍半氧烷(9-NPS)约5.13%, 其它杂质含量约为2.45%. 通过对ONPS高效液相色谱图峰形和同分异构体极性情况分析, 进一步证明ONPS分子中硝基取代发生于对位和间位. 使用超高效液相色谱(UPLC)对ONPS进行分析, 以更高的分离效率验证了HPLC的结果. 该方法可作为ONPS纯度的分析方法. 相似文献
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Investigation of Oxygen Vacancy and Interstitial Oxygen Defects in ZnO Films by Photoluminescence and X-Ray Photoelectron Spectroscopy 下载免费PDF全文
ZnO films prepared at different temperatures and annealed at 900^o C in oxygen are studied by photoluminescence (PL) and x-ray photoelectron spectroscopy (XPS). It is observed that in the PL of the as-grown films the green luminescence (GL) and the yellow luminescence (YL) are related, and after annealing the GL is restrained and the YL is enhanced. The 0 ls XPS results also show the coexistence of oxygen vacancy (Vo) and interstitial oxygen (Oi) before annealing and the quenching of the Vo after annealing. By combining the two results it is deduced that the GL and YL are related to the Vo and Oi defects, respectively. 相似文献
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通过在聚酰亚胺(PI)中分别添加笼型八氨基苯基硅倍半氧烷(OAPS)、 笼型八苯基硅倍半氧烷(OPS)、 梯形聚苯基硅倍半氧烷(PPSQ)和无机纳米SiO2, 制备了4种含硅聚酰亚胺(PI/Si)复合膜. 对PI/Si复合膜的相容性、 力学性能、 热性能和阻燃性能进行了研究. 结果表明, OAPS与PI间展现出较好的相容性, PPSQ次之, 而OPS, SiO2与PI的相容性较差; 但相容性与复合膜的力学和热性能无明显的对应关系. SiO2可提高PI的力学性能; PI/OAPS复合膜的Tg最高; OAPS, PPSQ或SiO2的加入使PI复合膜的热稳定性稍有提高, 而少量OPS的加入大大降低PI膜的热稳定性. 这类PI/Si复合膜的显著特点是能够大幅提高PI膜的极限氧指数, 含硅化合物能够增加PI燃烧后残炭量, 使残炭的形貌得到显著改善. PI/Si复合膜在燃烧过程中在表面形成一层白色含硅包裹层, 起到隔热隔氧及保护内层有机物不被燃烧的作用. 硅倍半氧烷对炭层形貌的改善显著, 展现出比SiO2更好的阻燃性能. 相似文献