氧分压对磁控溅射制备ZnO薄膜的结构及光学特性的影响

采用射频反应磁控溅射法在玻璃衬底上成功制备出具有c轴高择优取向的ZnO薄膜,利用X射线衍射及紫外-可见吸收和透射光谱研究了氧分压变化对ZnO薄膜的微观结构及光吸收特性的影响。结果表明,当工作气压恒定时,用射频反应磁控溅射制备的ZnO薄膜的生长行为主要取决于成膜空间中氧的密度,合适的氧分压能够提高ZnO薄膜的结晶质量;薄膜在可见光区的平均透过率达到90%以上,且随着氧分压的增大,薄膜的光学带隙发生了一定程度的变化。采用量子限域模型对薄膜的光学带隙作了相应的理论计算,计算结果与对样品吸收谱所作的拟合结果符合较好,二者的变化趋势完全一致,表明ZnO纳米晶粒较小时,薄膜光学带隙的变化与量子限域效应有很大关系。     

生长温度对磁控溅射ZnO薄膜的结晶特性和光学性能的影响

采用反应射频磁控溅射方法，在Si (100) 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、透射电子显微镜、X射线衍射分析、拉曼光谱等表征技术，研究了沉积温度 对ZnO薄膜的表面形貌、晶粒尺度、应力状态等结晶性能的影响；通过沉积温度对透射光谱 和光致荧光光谱的影响，探讨了ZnO薄膜的结晶特性与光学性能之间的关系.研究结果显示， 在室温至500℃的范围内，ZnO薄膜的晶粒尺寸随沉积温度的增加而增加，在沉积温度为500 ℃时达到最大；当沉积温度为750℃时，ZnO薄膜的晶粒尺度有所减小；在室温至750℃的范 围内，薄膜中ZnO晶粒与Si基体之间均存在着相对固定的外延关系；在沉积温度低于500℃时 ，制备的ZnO薄膜处于压应变状态，而750℃时沉积的薄膜表现为张应变状态.沉积温度的不 同导致ZnO薄膜的折射率、消光系数、光学禁带宽度以及光致荧光特性的变化，沉积温度对 紫外光致荧光特性起着决定性的作用.此外，探讨了影响薄膜近紫外光致荧光发射的可能因 素. 关键词： ZnO薄膜 表面形貌 微观结构 光学常数     

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     

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     

溶胶-凝胶法制备ZnO薄膜的成核-生长和失稳分解研究

采用溶胶-凝胶法在ZnWO₄单晶上制备出透明的ZnO薄膜.通过光学显微镜观察了Z nO薄膜的表面形貌.实验结果表明，ZnO薄膜的形成经历了表面成核，晶粒长大和岛的形成三 个不同的阶段.由于ZnO晶核是在非平衡条件下生长的，在生长过程中不可避免地出现了枝晶 生长和分形生长以及失稳分解. 关键词： 氧化锌薄膜 成核 枝晶生长 分形生长 失稳分解     

不同参数溅射的ZnO薄膜硫化后的特性

采用直流反应磁控溅射法在玻璃和石英衬底上沉积了ZnO薄膜, 然后将它们在H^２S气流中 硫化得到ZnS薄膜．用x射线粉末衍射仪(XRD)、扫描电子显微镜(SEM)和UV-VIS透过光谱对Zn S薄膜样品进行了分析．结果表明, 该ZnS薄膜为六角晶体结构, 沿(002)晶面择优取向生长, 其结晶状态和透过光谱与工作气压、Ar/O^２流量比密切相关. 当气压高于1Pa 时, 得 到厚度很小的ZnS薄膜; 而气压低于1Pa时, 沉积的ZnO薄膜则不能全部反应生成ZnS. 另外, 当Ar/O^２流量比低于4∶1或高于4∶1时, 结晶状态都会变差. 此外, 由于ZnS薄 膜具有高 的沿(002)晶面择优取向的生长特性, 使得退火或未退火ZnO薄膜硫化后的晶粒尺寸变化很小 . 关键词： ZnS薄膜 磁控溅射 ZnO硫化 太阳电池     

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     

离子注入Zn的Si(001)基片热氧化制备纳米ZnO团簇及其生长行为研究

采用离子注入技术将Zn离子注入Si（001）基片,并在大气环境下加热氧化制备了ZnO纳米团簇.利用电子探针、薄膜X射线衍射仪、原子力显微镜和透射电子显微镜,对注入和热氧化后的薄膜成分、表面形貌和微观结构进行表征,探讨了热氧化温度以及注入剂量对纳米ZnO团簇的成核过程及生长行为的影响.结果表明,Zn离子注入到Si基片表面后形成了Zn纳米团簇,热氧化过程中Zn离子向表面扩散,在表面SiO₂非晶层和Si基片多晶区的界面处形成纳米团簇.热氧化温度是影响ZnO纳米团簇结晶质量的一个重要参数.随着热氧化温度的升高,金属Zn的衍射峰强度逐渐变弱并消失,而ZnO的（101）衍射峰强度逐渐增强.当热氧化温度高于800 ℃以后,ZnO与SiO₂之间开始发生化学反应形成Zn₂SiO₄. 关键词： ZnO纳米团簇 离子注入 微观结构 形貌分析     

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     

温度对Si上MOCVD-ZnO成核与薄膜生长特性的影响

采用金属有机化学气相沉积(MOCVD)方法在Si衬底上进行了ZnO的成核与薄膜生长研究。ZnO薄膜的形貌和结晶特性由成核和后期生长过程共同决定,初期成核温度决定了其尺寸和密度,进而影响后期ZnO主层的生长行为,但由于高温对后期ZnO纳米柱横向生长的抑制,纳米柱的尺寸并没有因为成核尺寸的增大而变大,因此在560℃得到了晶柱尺寸最大、密度最小的ZnO薄膜。最后通过改变成核温度,优化了ZnO外延膜的结晶质量。     

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 关键词： ZnO薄膜 反应磁控溅射 基片处理 形貌分析     

Optical and electrical properties of nanocrystal zinc oxide films prepared by dc magnetron sputtering at different sputtering pressures

The nanocrystal thin films of zinc oxide doped by Al (ZnO:Al) were deposited by dc reactive magnetron sputtering on the glass substrates, in the pressure range of 33-51 Pa. From the X-ray diffraction patterns, the nanocrystalline structure of ZnO:Al films and the grain size were determined. The optical transmission spectra depend from the sputtering pressure, but their average value was 90% in the range from 33 Pa to 47 Pa. Also, the sputtering pressure changes the optical band gap of ZnO:Al films, which is highest for films deposited at 37 Pa, 40 Pa and 47 Pa. The obtained films at room temperature have a sheet resistance of 190 Ω/cm² which increases with time, but the films annealed at temperature of 400 °C have constant resistance. The surface morphology of the films was studied by Scanning electron microscopy. XPS spectra showed that the peak of O1s of the as-deposited films is smaller than the peak of the annealed ZnO:Al films.     

Growth and characterization of thin ZnO films deposited on glass substrates by electrodeposition technique

Electrodeposition technique was used in order to produce nanometric zinc oxide films on glass insulating substrates. The effect of electrolyte concentration and applied current density on the formation and growth of electrodeposited Zn thin films in aqueous solutions of ZnSO₄ were studied. After a thermal oxidation, a characterization of the structural morphology of the films deposited was carried out by optical microscopy (OM), atomic force microscopy (AFM), scanning electron microscopy (SEM) and by grazing incidence X-rays diffraction (GIXD). These characterization techniques show that the grains size of the films after oxidation at temperature 450 °C is between 5 and 15 nm, as well as the structure is polycrystalline nature with several orientations. UV/vis spectrophotometry confirms that it is possible to obtain transparent good ZnO films with an average transmittance of approximately 80% within the visible wavelength region, as well as the optical gap of obtained ZnO films is 3.17 eV.     

Pulsed laser deposition of ZnO in N2O atmosphere

The contribution deals with ZnO thin layers doped by nitrogen which were prepared by pulsed laser deposition in N₂O ambient atmosphere. Our approach is based on ablation of undoped ZnO target in active atmosphere containing N₂O gas without any supporting excitation equipment in parallel. Ablation of ZnO target was performed at different pressures (1–32 Pa) of N₂O ambient atmosphere by pulsed Nd:YAG laser (at 355 nm). Layers of ZnO were grown on different substrates (Si, sapphire, fused silica) and their properties were investigated by various analytical methods: scanning electron microscopy (SEM), secondary ion mass spectroscopy (SIMS), X-ray diffraction (XRD), and optical transmission spectroscopy. The results confirmed incorporation of nitrogen into ZnO layers and its concentration was pressure dependent. According to SIMS analysis, there is a certain pressure level (above 10 Pa) when the presence of N becomes negligible. Transmittance spectra showed increasing of the optical band gap (E _g) according to the pressure of N₂O.     

Room temperature transparent conducting oxides based on zinc oxide thin films

Doped zinc oxide thin films are grown on glass substrate at room temperature under oxygen atmosphere, using pulsed laser deposition (PLD). O₂ pressure below 1 Pa leads to conductive films. A careful characterization of the film stoichiometry and microstructure using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM) concludes on a decrease in crystallinity with Al and Ga additions (≤3%). The progressive loss of the (0 0 2) orientation is associated with a variation of the c parameter value as a function of the film thickness and substrate nature. ZnO:Al and ZnO:Ga thin films show a high optical transmittance (>80%) with an increase in band gap from 3.27 eV (pure ZnO) to 3.88 eV and 3.61 eV for Al and Ga doping, respectively. Optical carrier concentration, optical mobility and optical resistivity are deduced from simulation of the optical data.     

Structural and optical properties of Er, Yb co-doped Y2O3 thin films

Thin Er³⁺, Yb³⁺ co-doped Y₂O₃ films were grown on (1 0 0) YAG substrates by pulsed laser deposition. Ceramic targets having different active ion concentration were used for ablation. The influence of the rare-earth content and oxygen pressure applied during the deposition on the structural, morphological and optical properties of the films were investigated. The films deposited at the lower pressure, 1 Pa, and at 1/10 Er to Yb doping ratio are highly textured along the (1 1 1) direction of the Y₂O₃ cubic phase. In addition to the crystalline structure, these films possess smoother surface compared to those prepared at the higher pressure, 10 Pa. All other films are polycrystalline, consisting of cubic and monoclinic phases of Y₂O₃. The rougher surface of the films produced at the higher-pressure leads to higher scattering losses and different behavior of the reflectivity spectra. Optical anisotropy in the films of less than 0.004 was measured regardless of the monoclinic structure obtained. Waveguide losses of about 1 dB/cm at 633 nm were obtained for the films produced at the lower oxygen pressure.     

溅射气氛对RF反应磁控溅射制备ZnO薄膜微结构及光致发光特性的影响

用射频反应磁控溅射法在不同溅射压强和氩氧比下制备了ZnO薄膜,通过X射线衍射(XRD)、扫描电镜(SEM)和光致发光(PL)谱等研究了溅射压强和氩氧比对ZnO薄膜结构和光学性质的影响。测量结果显示,所制备的ZnO薄膜为六角纤锌矿结构,具有沿c轴的择优取向;溅射压强P=0.6Pa,氩氧比Ar/O2=20/5.5sccm时,(002)晶面衍射峰强度和平均晶粒尺寸较大,(O02)XRD峰半峰全宽(FWHM)最小,光致发光紫外峰强度最强。     

Comparative study on structural and optical properties of ZnO thin films prepared by PLD using ZnO powder target and ceramic target

Zinc oxide thin films have been obtained in O₂ ambient at a pressure of 1.3 Pa by pulsed laser deposition (PLD) using ZnO powder target and ceramic target. The effect of temperature on structural and optical properties of ZnO thin films was investigated systematically by XRD, SEM, FTIR and PL spectra. The results show that the best structural and optical properties can be achieved for ZnO thin film fabricated at 700 °C using powder target and at 400 °C using ceramic target, respectively. The PL spectrum reveals that the efficiency of UV emission of ZnO thin film fabricated by using powder target is low, and the defect emission of ZnO thin film derived from Zn_i and O_i is high.