蓝宝石基片的处理方法对ZnO薄膜生长行为的影响

采用反应射频磁控溅射方法，在经过不同方法处理的蓝宝石基片上，在同一条件下沉积了ZnO薄膜.利用原子力显微镜、X射线衍射、反射式高能电子衍射等分析技术，对基片和薄膜的结构、表面形貌进行了系统表征.研究结果显示，不同退火条件下的蓝宝石基片表面结构之间没有本质的差异，均为α-Al₂O₃ (001)晶面，但基片表面形貌的变化较大.在不同方法处理的蓝宝石基片上生长的ZnO薄膜均具有高c轴取向的织构特征，但薄膜的表面形貌差异较大.基片经真空退火处     

Si(001)基片上反应射频磁控溅射ZnO薄膜的两步生长方法

利用反应射频磁控溅射技术，采用两步生长方法制备了ZnO薄膜，探讨了基片刻蚀时间和低温过渡层沉积时间对ZnO薄膜生长行为的影响.研究结果表明，低温ZnO过渡层的沉积时间所导致的薄膜表面形貌的变化与过渡层在Si(001)表面的覆盖度有关.当低温过渡层尚未完全覆盖基片表面时，ZnO薄膜的表面岛尺度较小、表面粗糙度较大，薄膜应力较大；当低温过渡层完全覆盖Si(001)基片后，ZnO薄膜的表面岛尺度较大、表面粗糙度较小，薄膜应力较小.基片刻蚀时间对薄膜表面形貌的影响与低温过渡层的成核密度有关.随着刻蚀时间的增加，ZnO薄膜的表面粗糙度逐渐下降，表面形貌自仿射结构的关联长度逐渐减小. 关键词： ZnO薄膜 反应射频磁控溅射 两步生长 形貌分析     

磁控溅射ZnO薄膜的成核机制及表面形貌演化动力学研究

利用原子力显微镜分析了ZnO薄膜在具有本征氧化层的Si(100)和Si(111)基片上的表面形貌 随沉积时间的演化. 通过对薄膜生长形貌的动力学标度表征，研究了射频反应磁控溅射条件 下，ZnO薄膜的成核过程及生长动力学行为. 研究发现，ZnO在基片表面的成核过程可分为初 期成核阶段、低速率成核阶段和二次成核阶段. 对于Si(100)基片，三个成核阶段的生长指 数分别为β₁=1.04，β₂=0.25±0.01，β₃=0.74；对 于Si(11 关键词： ZnO薄膜 磁控溅射 生长动力学 成核机制     

氧化处理的蓝宝石基片上沉积的ZnO/MgO多量子阱的结构及光学性质研究

采用射频反应磁控溅射的方法，在经过氧化处理的Al₂O₃（0001）基片上制备了具有良好调制结构的ZnO/MgO多层膜量子阱.利用X射线反射率测量、X射线衍射分析、电子探针显微分析、原子力显微镜、透射光谱以及光致发光光谱等表征技术，研究了ZnO/MgO多量子阱的结构、表面形貌和光致发光等特性.XRD以及扫描的结果表明多层膜样品具有高c轴择优取向并且与蓝宝石基片有良好的外延关系.通过X射线反射率测量的结果得到多量子阱的调制周期，结合电子 关键词： ZnO/MgO 多量子阱 反应磁控溅射 变温光谱     

Ti缓冲层及退火处理对Si(111)基片上生长的ZnO薄膜结构和发光特性的影响

采用反应磁控溅射法在Si（111）基片上制备了带有Ti缓冲层的高c轴取向ZnO薄膜.通过X射线衍射分析和光致荧光光谱测量，研究了Ti缓冲层厚度和退火处理对ZnO薄膜结晶质量和光致荧光特性的影响.研究结果表明，Ti缓冲层的引入可以有效改善Si基片上ZnO薄膜的发光性能，但缓冲层存在一个最佳的厚度.薄膜应力是影响ZnO薄膜紫外荧光发射性能的重要因素，较小的残余应力对ZnO薄膜的紫外荧光发射是有利的，残余应力的存在可以改变ZnO薄膜紫外荧光发射能量.随着退火温度的增加，薄膜中的张应力增大，导致带隙宽度减小以及激子复合跃迁峰逐渐向低能方向移动. 关键词： ZnO薄膜 缓冲层 退火处理 应力分析     

工作气压对磁控溅射ZnO薄膜结晶特性及生长行为的影响

采用射频反应磁控溅射方法，在Si(001)基片上制备了具有高c轴择优取向的ZnO薄膜.利用原子力显微镜、X射线衍射、透射电子显微镜和透射光谱分析技术，对不同工作气压下合成的ZnO薄膜的表面形貌、微观结构和光学性能进行表征，研究了工作气压对ZnO薄膜的结晶性能以及生长行为的影响.研究结果显示：对于Ar/O₂流量比例接近1∶1的固定比值下，ZnO薄膜的生长行为主要取决于成膜空间中氧的密度，临界工作气压介于0.5—1.0 Pa之间.当工作气压小于临界值时，ZnO薄膜的成核密度较高，且随工作气压的变化明显，ZnO的生长行为受控于氧的密度，属于氧支配的薄膜生长；当工作气压大于临界值以后，ZnO薄膜的成核密度基本保持不变，Zn原子的数量决定薄膜的生长速率；在0.1—5.0 Pa的工作气压范围内，均可获得高度c轴取向的ZnO薄膜，但工作气压的变化改变着ZnO晶粒之间的界面特征和取向关系.随着工作气压的增加，ZnO晶粒之间的界面失配缺陷减少，但平面织构特征逐渐消失，三叉晶界的空洞逐渐扩大，薄膜的密度下降，折射率减小. 关键词： ZnO薄膜 磁控溅射 表面形貌 微观结构 光学性能     

退火温度对ZnO薄膜结构和发光特性的影响

采用反应射频磁控溅射法在 Si(100)基片上制备了高c轴择优取向的ZnO薄膜，研究了退火温度对ZnO薄膜的晶粒尺度、应力状态、成分和发光光谱的影响，探讨了ZnO薄膜的紫外发光光谱和可见发光光谱与薄膜的微观状态之间的关系.研究结果显示,在600—1000℃退火温度范围内，退火对薄膜的织构取向的影响较小，但薄膜的应力状态和成分有比较明显的变化.室温下光致发光光谱分析发现，薄膜的近紫外光谱特征与薄膜的晶粒尺度和缺陷状态之间存在着明显的对应关系；而近紫外光谱随退火温度升高所呈现的整体峰位红移是各激子峰相对比例变 关键词： ZnO薄膜 退火 光致发光 射频反应磁控溅射 可见光发射     

ZnO退火条件对硫化法制备的ZnS薄膜特性的影响

采用反应磁控溅射法在玻璃和石英衬底上沉积了ZnO薄膜, 然后经过不同条件退火和在H22S气氛中硫化最终得到ZnS薄膜. 用x射线粉末衍射仪、扫描电子显微镜和UV—VIS分光光度计 对ZnS薄膜样品进行了分析. 结果表明, ZnO薄膜硫化后的晶体结构和光学性质取决于它的退 火条件. 真空和纯O2₂中退火的ZnO薄膜硫化后只是部分形成六角晶系结构的ZnS . 而在空气 和纯N2₂中退火的ZnO薄膜则全部转变为ZnS, 在可见光范围内的光透过率 关键词： ZnS薄膜 磁控溅射 ZnO硫化 太阳电池     

高温退火对蓝宝石基片的表面形貌和对CeO2缓冲层以及Tl-2212超导薄膜生长的影响

研究了蓝宝石(1102)基片在不同温度和时间下退火时表面形貌和表面相结构的变化，以及它对CeO₂缓冲层和Tl-2212超导薄膜生长的影响.原子力显微镜(AFM)研究表明，在流动氧环境中1000℃温度下退火，蓝宝石(1102)的表面首先局部区域形成台阶结构，然后表面形成叠层台阶结构，随着退火时间的延长，表面发生了台阶合并现象，表面形貌最终演化为稳定的具有光滑平台的宽台阶结构.XRD测试表明，通过高温热处理可以大幅度提高蓝宝石基片表面结构的完整性.在1000℃温度下热处理20 h的蓝宝石     

磁控共溅射法制备的Zn2GeO4多晶薄膜结构及其光致发光研究

用射频磁控共溅射方法在不同温度的单晶硅基片上生长薄膜，然后在800℃真空环境下对薄膜进行退火处理，成功获得了结晶状态良好的Zn₂GeO₄多晶薄膜.利用X射线衍射(XRD)，X射线光电子能谱(XPS)和原子力显微镜(AFM)对薄膜进行了结构、成分和形貌分析，研究了基片温度对三者的影响. 结果显示，当基片温度升高到400℃以上时，薄膜中的Zn₂GeO₄晶粒在(220)方向上显示出了明显的择优取向. 当基片温度在500—600℃范围内，有利于GeO₂结晶相的形成. XPS显示薄膜中存在着Zn₂GeO₄，GeO₂，GeO，ZnO四种化合态. 同时，随着基片温度的升高，晶粒尺寸增大且薄膜表面趋于平整. 薄膜的光致发光在绿光带存在中心波长为530和550nm两个峰，应该归因于主体材料Zn₂GeO₄中两个不同的Ge²⁺的发光中心. 关键词： 射频磁控溅射 2GeO₄')" href="#">Zn₂GeO₄ 荧光体     

涂层导体用金属基带表面对过渡层成核的机理研究

涂层导体用金属基带的表面状况对在其上制备的过渡层的形貌和取向有很大影响.在Ni单晶、轧制辅助双轴织构基带(RABiTS)Ni和经过硫化处理的Ni基带三种不同衬底上采用磁控溅射法制备了CeO₂过渡层.结果表明,在Ni单晶和硫化处理的Ni基带上制备的CeO₂薄膜取向较差,而在RABiTS Ni上制备的CeO₂薄膜完全呈c轴取向,表面平整致密.反射高能电子衍射图显示,RABiTS Ni具有的c(2×2)的S超结构对CeO₂薄膜的取向生长起到了很重要的作用. 关键词： 涂层导体 金属基带 超结构 过渡层     

氧分压对Mg掺杂ZnO薄膜结晶质量和光学特性的影响

利用脉冲激光沉积技术,通过改变沉积过程中的氧气压力,在蓝宝石(0001)基片上制备了一系列ZnMgO合金.通过X射线衍射、反射和透射光谱以及室温和变温荧光光谱,对薄膜的结构和光学性能进行了系统地表征,分析了工作气压对ZnMgO合金薄膜的结晶质量及光学特性的影响.研究结果表明:随着沉积环境中氧气压力的增大,ZnMgO薄膜的结晶质量下降,富氧环境下,与蓝宝石晶格平行的ZnO晶粒的出现是导致薄膜结晶质量下降的主要原因;相对于本征ZnO,不同氧气环境下沉积的ZnMgO薄膜的紫外荧光峰均出现了不同程度的蓝移.随着工 关键词： ZnO Mg掺杂 脉冲激光沉积 薄膜生长 光学特性     

Characteristics of ZnO epilayer on the post-annealed buffer layer on GaN/sapphire substrate by pulsed laser deposition

We employed epi-GaN substrates for ZnO film growth, and studied the deposition and post-annealing effects. ZnO films were grown by pulsed laser deposition (PLD) method. The as-grown films were annealed for one hour under atmospheric pressure air. ZnO morphologies after annealing were investigated and the post-annealed ZnO films grown at T _g =700^oC have very smooth surfaces and the rms with roughness is about 0.5 nm. Finally, ZnO post-annealed buffer layer was inserted between ZnO epilayer and GaN/sapphire substrates. It is confirmed by AFM that growth temperature of 700^oC helps the films grow in step-flow growth mode. It is observed by cathode luminescence spectrum that the ZnO film grown at 700^oC has very low visible luminescence, indicating the decrease of the deep level defects. It is also revealed by Hall measurements that carrier concentration is decreased by increasing the growth temperatures. It is suggested that low temperature buffer layer growth and post-annealing technique can be used to fabricate ZnO hetero-epitaxy.     

Surface morphology of ZnO buffer layer and its effects on the growth of GaN films on Si substrates by magnetron sputtering

ZnO thin films were first prepared on Si(111) substrates using a radio frequency magnetron sputtering system. Then the as-grown ZnO films were annealed in oxygen ambient at temperatures of 700, 800, 900, and 1000°C , respectively. The morphologies of ZnO films were studied by an atom force microscope (AFM). Subsequently, GaN epilayers about 500 nm thick were deposited on the ZnO buffer layers. The GaN/ZnO films were annealed in NH₃ ambient at 900°C. The microstructure, morphology and optical properties of GaN films were studied by x-ray diffraction (XRD), AFM, scanning electron microscopy (SEM) and photoluminescence (PL). The results are shown, their properties having been investigated particularly as a function of the ZnO layers. For better growth of the GaN films, the optimal annealing temperature of the ZnO buffer layers was 900°C.     

Nanostructure evolution in cluster-assembled WO x films synthesized by radio-frequency assisted laser ablation

We deposited WO _x films by radio frequency assisted pulsed laser deposition (RF-PLD). We explored the roles of substrate temperature and ambient gas pressure-composition on film nanostructure to maximise the film surface area in view of gas sensing applications. A W target was ablated in highly reactive O₂ at 5 Pa and 700 Pa, as well as in a mixed oxygen-helium atmosphere at 700 Pa. Corning glass was used as the substrate, at increasing temperatures. Process parameters such as laser fluence and wavelength, radio-frequency power, target to substrate distance were kept fixed. The influence of the deposition parameters on roughness, morphology, nanostructure, and bond coordination of the deposited films were studied by Atomic Force Microscopy, Scanning Electron Microscopy, Transmission Electron Microscopy, and micro-Raman spectroscopy. Nanoparticle formation, the development of an extended, open nanostructure and its evolution toward compact films are discussed.     

制备工艺对Zn1-xMgxO薄膜结构及光学性能的影响

采用脉冲激光沉积（PLD）方法在单晶Si（100）衬底上沿c轴方向生长单晶Zn_1-xMg_xO薄膜，通过X射线衍射（XRD）、原子力显微镜（AFM）、扫描电镜（SEM）和荧光光谱（PL）研究了膜厚、Mg含量、退火温度及氧气氛等制备工艺对Zn_1-xMg_xO薄膜的结构、形貌和光学性质的影响.实验结果表明，Mg含量x≤0.15时, Zn_{关键词： 1-x}Mg_xO薄膜')" href="#">Zn_1-xMg_xO薄膜 制备工艺 结构 光学性质     

Surface roughening by anisotropic adatom kinetics in epitaxial growth of La0.67Ca0.33MnO3

The growth mechanisms and surface morphology of colossal magnetoresistance (CMR) La_0.67Ca_0.33MnO₃ films deposited by rf magnetron sputtering on SrTiO₃(0 0 1) substrates are investigated. The films are epitaxial, coherently strained and ferromagnetic. It is found that at early growth stages, in nanometric films, a layer-by-layer mechanism dominates, which results in step and terrace surface morphology. Upon further growth, the flat surface becomes unstable when large two-dimensional (2D) islands form. The Erlich-Schwoebel step-edge energy barrier induces an anisotropic adatom kinetics that favors 2D nucleation on top of the islands as it reduces downhill adatom current. As a result, there is an evolution with growth to mound-like structures of increasing height. Critical thickness for mound formation and average mound separation can be tuned by substrate miscut angle and growth temperature. These results provide a detailed understanding of the roughening process in manganites and are relevant for the controlled fabrication of CMR films, in particular for its use in epitaxial heterostructures.     

Seed-assisted growth of epitaxial ZnO nanorod arrays with self-organized periodicity and directional alignment

In this article we report the seed-assisted growth of epitaxial ZnO nanorod (NR) arrays on (0 0 0 1) plane sapphire substrates at low temperatures in aqueous solutions. The self-organized periodic ZnO NR rows with a fairly constant separation were directly grown on bare sapphire surfaces, without the need for any complicated lithography or use of pre-patterned catalysts. The spatial ordering of the ZnO NRs was significantly influenced by the seed growth conditions and by the presence of a self-organized step structure on the annealed sapphire surface. In addition, the effect of the conditions employed to prepare the seeds, including growth parameters and post-growth annealing treatment, on the epitaxial relationship between the ZnO NRs and the sapphire substrate was systematically investigated by X-ray diffraction (XRD) measurements and transmission electron microscopy (TEM) observations. Post-growth annealing of the ZnO seeds changed the morphologies and crystallographic alignment of the generated ZnO nanostructures significantly, as a result of the formation of epitaxial spinel ZnAl₂O₄ interlayers, facilitated by zinc cation diffusion and solid state reactions at high temperature.     

Effects of different annealing atmospheres on the surface and microstructural properties of ZnO thin films grown on p-Si (1 0 0) substrates

Effects of different annealing atmospheres on the surface and microstructural properties of ZnO thin films grown on Si (1 0 0) substrates were investigated. X-ray diffraction results showed that the crystallinity of the ZnO thin film annealed in an oxygen atmosphere was better than that annealed in a nitrogen atmosphere. Atomic force microscopy and transmission electron microscopy (TEM) images showed that the surfaces of the ZnO thin films annealed in a nitrogen atmosphere became very rough in contrast to those annealed in an oxygen atmosphere. High-resolution TEM images showed that many stacking faults and tilted grains could be observed in the ZnO thin films annealed in a nitrogen atmosphere in contrast to those annealed in an oxygen atmosphere. Surface morphology and microstructural property variations due to different annealing atmospheres in ZnO thin films are also described on the basis of the experimental results.