Effect of pre-heating temperature on structural and optical properties of sol-gel derived Zn<Subscript>0.8</Subscript>Cd<Subscript>0.2</Subscript>O thin films

Zn_0.8Cd_0.2O thin films prepared using the spin-coating method were investigated. X-ray diffraction, scanning electron microscopy, and UV-Vis spectrophotometry were employed to illustrate the effects of the pre-heating temperature on the crystalline structure, surface morphology and transmission spectra of Zn_0.8Cd_0.2O thin films. When the thin films were pre-heated at 150 °C, polycrystalline ZnO thin films were obtained. When the thin films were pre-heated at temperatures of 200 °C or higher, preferential growth of ZnO nanocrystals along the c-axis was observed. Transmission spectra showed that thin films with high transmission in the visible light range were prepared and effective bandgap energies of these thin films decreased from 3.19 eV to 3.08 eV when the pre-heating temperature increased from 150 °C to 300 °C.     

Influence of crystal structure on friction coefficient of ZnO films prepared by atomic layer deposition

In this work, the influence of crystal structure on the friction coefficient of zinc oxide(ZnO) films was studied. The ZnO films were deposited on a Si(100) substrate using an atomic layer deposition process, and the crystal structure of the ZnO films was changed by adjusting the substrate temperature. The surface morphology and the crystal structure of the Zn O films were measured by an atomic force microscope and an X-ray diffractometer, respectively, and the friction coefficient of the ZnO films was measured by a ball-on-disk dry sliding tester. The results show that the ZnO films deposited at substrate temperatures below 200°C are dominated by(100),(002) and(101)-orientated crystals, while the ZnO films deposited at substrate temperatures above 250°C are dominated by(002)-orientated crystals, and that the crystal structure influences the friction coefficient of ZnO films greatly. The ZnO films with(002)-orientated crystals possess a larger friction coefficient than those with other orientated crystals. In order to verify this conclusion, we measured the friction behavior of the ZnO single crystals with different orientations. The results are consistent well with our conclusion.     

Optimization of the process for preparing Al-doped ZnO thin films by sol-gel method

Transparent and conducting Al-doped ZnO thin films with c-axis-preferred orientation were prepared on glass substrate via sol-gel route. The physical and chemical changes during thermal treatment were analyzed by TG-DSC spectra and the crystallization quality was characterized by XRD patterns. The optimized preheating and post-heating temperatures were determined at ~420℃ and ~530℃, respec-tively. From thermodynamic and kinetics views, we investigated the mechanism of orientation growth with (002) plane parallel to the substrates. The surface morphologies of the films, post-heated at 420℃, 450℃, 530℃ and 550℃, respectively, were observed by SEM micrographs. The film post-heated at 530℃ shows a homogenous dense microstructure and exhibits the minimum sheet resistance of 140 Ω/Sq. The visible optical transmittance of all the films is beyond 90%. In addition, the annealing treatment in vacuum can contribute greatly to the electrical conductivity.     

Correlations between the Optical Properties and the Microstructure of TiO2 Thin Films Prepared by Reactive Electron-beam Evaporation

High refractive index TiO₂ thin films were deposited on BK7 glass by reactive electron—beam (REB) evaporation at pressure of 2×10⁻² Pa, deposition rate of 0.2 nm/s and at various substrate temperatures from 120°C to 300°C. The refractive index and the thickness of the films were measured by visible spectroscopic ellipsometry (SE) and determined from transmission spectra. Optical properties and structure features were characterized by UV-VIS, SEM and XRD, respectively. The measurement and analysis on transmission spectra of all samples show that with the substrate temperature increasing from 120°C to 300°C, the refractive indices of thin films increase from 1.7 to 2.1 and the films after heat treatment have higher refractive indices due to its crystallizing. The XRD analysis results indicate that the structure of TiO₂ thin films deposited on BK7 glass at substrate temperatures of 120°C, 200°C and 300°C is amorphous, after post-annealing under air condition at 400°C for 1 hour, the amorphous structure is crystallized, the crystal phase is of 100% anatase with strong preferred orientation (004) and the grain size of crystalline is within 3.6–8.1 nm, which is consistent with results from SEM observation. WANG Xue-hua: Born in 1976. Funded by the Youth Project Foundation of Hubei Provincial Education Department (No. 2003B00)     

磁控溅射法生长ZnO薄膜的结构和表面形貌特性

采用射频磁控溅射方法,在Si（111）和玻璃基片上制备ZnO薄膜。研究衬底温度和基片类型对薄膜结构、表面形貌的影响。结果显示,所有ZnO薄膜沿c轴择优生长,同种基片类型上生长的薄膜,随着衬底温度升高,（002）衍射峰强度和表面粗糙度增高;相同衬底温度下生长的ZnO薄膜,Si基片上制备的薄膜（002）衍射峰强度和表面粗糙度小于玻璃片上的。基片类型影响薄膜应力状态,玻璃片上制备的ZnO薄膜处于张应变状态,Si基片上的薄膜处于压应变状态;对于同种基片类型上生长的ZnO薄膜,衬底温度升高,应力减小。Si衬底上、300℃下沉积的薄膜颗粒尺寸分布呈正态。     

Structural,optical and electrical properties of Li-doped ZnO thin films influenced by annealing temperature

Li-doped Zn O thin films had been grown by radio frequency magnetron sputtering and then annealed under various annealing temperatures. The characteristics of Zn O films were examined by XRD, FESEM, Hall measurement and optical transmission spectra. Results showed that p type conduction was observed in Lidoped Zn O films annealed at 500-600 ℃ and the p type Zn O films possessed a good crystalline with c-axis orientation, dense surface, and average transmission of about 85% in visible spectral region.     

不同衬底温度对ZnO薄膜结构和光学性质的影响

利用磁控溅射在玻璃基片上制备了不同衬底温度下的ZnO薄膜.借助X射线衍射仪(XRD)、吸收光谱、光致发光谱(PL)等手段研究了衬底温度对ZnO薄膜的微结构、光致发光性能的影响.结果表明:所有样品均呈现ZnO六角纤锌矿结构且具有高度c轴择优取向;ZnO薄膜在可见区的吸收系数很小,在紫外区有很高的吸收系数;室温下的荧光光谱显示薄膜具有较强的紫光发射.     

化学法在Ni-W基带上制备Ag缓冲层研究

在双轴织构的Ni-W基带上,采用化学镀银法为YBa2Cu3O7-δ（YBCO）涂层导体制备Ag缓冲层薄膜,并通过XRD和φ扫描研究烧结温度和镀银次数对Ag薄膜取向的影响。结果表明,在Ar-H2混合气氛下,于870℃镀银5次所制备的薄膜具有（200）晶面单一取向;采用化学法制备的Ag薄膜有较好的外延性,且适用于涂层导体中的单一导电型缓冲层。     

Investigations of ZnO thin films deposited by a reactive pulsed laser ablation

Highly transparent ZnO thin films were deposited at different substrate temperatures by pulsed laser deposition in an oxygen atmosphere. The thin films were characterized by various techniques including X-ray diffraction, scanning electron microscopy, optical absorption, and photoluminescence. We demonstrated that oriented wurtzite ZnO thin films could be deposited at room temperature using a high purity zinc target. Variable temperature photoluminescence revealed new characteristics in the band edge emission. The underlying mechanism for the observed phenomena was also discussed.     

Influence of annealing temperature on the properties of TiO2 films annealed by ex situ and in situ TEM

TiO₂ thin films were deposited on quartz substrates by DC reactive magnetron sputtering of a pure Ti target in Ar/O₂ plasma at room temperature. The TiO₂ films were annealed at different temperatures ranging from 300 to 800 °C in a tube furnace under flowing oxygen gas for half an hour each. The effect of annealing temperatures on the structure, optical properties, and morphologies were presented and discussed by using X-ray diffraction, optical absorption spectrum, and atomic force microscope. The films show the presence of diffraction peaks from the (101), (004), (200) and (105) lattice planes of the anatase TiO₂ lattice. The direct band gap of the annealed films decreases with the increase of annealing temperature. While, the roughness of the films increases with the increases of annealing temperature, and some significant roughness changes of the TiO₂ film surfaces were observed after the annealing temperature reached 800 °C. Moreover, the influences of annealing on the microstructures of the TiO₂ film were investigated also by in situ observation in transmission electron microscope.     

退火温度对Al掺杂ZnO薄膜结构和性能的影响

采用直流磁控溅射技术,在玻璃衬底上制备了ZnO:Al(ZAO)薄膜样品。其他参数不变,在不同的温度下对样品进行了退火处理,研究了薄膜的结构性质、电学和光学性质随退火温度的变化关系。实验结果表明:在退火温度为200℃时,ZAO薄膜具有较优的光电性能,其电阻率为9.62×10-5.cm,可见光区平均透射率为89.2%。     

Preparation of TiO<Subscript>2</Subscript> thin film by the LPD method on functionalized organic self-assembled monolayers

In this paper, uniform titania (TiO₂) films have been formed at 50° on silanol SAMs by the liquid-phase deposition (LPD) method at a temperature below 100°C. OTS (Octadecyltrichloro-Silane) self-assembled monolayers (SAMs) on glass wafers were used as substrates for the deposition of titanium dioxide thin films. This functionalized organic surface has shown to be effective for promoting the growth of films from titanic aqueous solutions by the LPD method at a low temperature below 100°C. The crystal phase composition, microstructure and topography of the as-prepared films were characterized by various techniques, including X-ray diffraction (XRD), scanning electron microscopy (SEM), and atomic force microscopy (AFM). The results indicate that the as-prepared thin films are purely crystallized anatase TiO₂ constituted by nanorods after being annealed at 500°. The pH values, concentration of reactants, and deposition temperatures play important roles in the growth of TiO₂ thin films. Support by the National Natural Science Foundation of China (Grant No. 50672055) and National Key Technology R&D Program (Grant No. 2006BAF02A28)     

Orientation of Bi<Subscript>3.2</Subscript>La<Subscript>0.8</Subscript>Ti<Subscript>3</Subscript>O<Subscript>12</Subscript> ferroelectric thin films with different annealing schedules

Fatigue-free Bi_3.2La_0.8Ti₃O₁₂ ferroelectric thin films were successfully prepared on p-Si (100) substrates using metalorganic solution deposition process. The orientation and formation of 5-layers thin films were studied under different processing conditions using XRD. Experimental results indicate that increase in annealing time at 700 °C after preannealing for 10 min at 400 °C can remarkably increase (200)-orientation of the films derived from the precursor solutions with two contents of citric acid. Meanwhile, high content of citric acid increases the film thickness and is conducive to the a-orientation of the films with the preannealing, and low concentration of the solution is conducive to the c-orientation of the films without the preannealing.     

Fabrication of Poly-Si Thin Film on Glass Substrate by Aluminum-induced Crystallization

Amorphous silicon （ a-Si ） thin films were deposited on glass substrate by PECVD, and polycrystalline silicon （ poly- Si ） thin films were prepared by aluminum- induced crystallization （ AlC ）. The effects of annealing temperature on the microstructure and morphology were investigated. The AlC poly-Si thin films were characterized by XRD, Raman and SEM. It is found that a-Si thin film has a amorphous structure after annealing at 400℃ for 20 min, a-Si films begin to crystallize after annealing at 450 ℃ for 20 min, and the crystallinity of a-Si thin films is enhanced obviously with the increment of annealing termperature.     

Effect of Annealing on Structural, Optical and Electrical Properties of CdS Thin Films Grown by ILGAR

CdS thin films were deposited by ILGAR （ ion lay gas reaction） method. The effect of annealing temperature under N2 atmosphere on the structural, chemical, topographical development and optical and electrical properties of CdS thin films was investigated by XRD, SEM, XPS, UV- VIS and two-probe technique. It is found that the cubic-phase of as-deposited CdS film transforms to hexagonal phase with a perfected orientation along （002） plane at 300 ℃ . The band gap decreases with increasing annealing temperature until 300 ℃ , which is consistent with the grain growth. The fall of dark and light resistivitiy is obvious with increasing annealing temperature, corresponding to the continuous grain growth and deviation of stoichiometry at higher temperature. The smooth and uniform surface of as-deposited films becomes rougher through thermal treatment, which is related to grain growth and sublimation of CdS at a higher annealing temperature.     

Preparation,microstructure and magnetic properties of NiZn ferrite thin films by spin spray plating

NiZn ferrite thin fihns were performed on glass substrates of 85 ℃ by spin spray plating method. X-ray diffraction patterns of the films show that the samples have a cubic spinel structure with no extra lines corresponding to any other phases between 75 ℃ and 85 ℃. As the pH value of oxidizing solution increases to 8.3, the saturation magnetization increases to 3.13 × 10^5 A/m and resistivity to 127 m Ω ·cm. Film deposited at pH 7.8 has a smooth surface and definite columnar structure. The large wavy flakes were observed at pH 8.3. The high real part of complex permeability μ′ up to 36.1 and the imaginary part μ″ up to 53.2 were observed at 0.5 GHz by short microstrip line perturbation method. The μ″ of thin film has values higher than 20 at the frequencies between 0.5 GHz and 2 GHz, the film is a promising anti-noise material for high frequency applications,     

在蓝宝石、MgO衬底上ZnO波导膜的制备

以ZnO烧结陶瓷为靶材,应用射频磁控溅射技术在（001）蓝宝石、（100）MgO衬底上制备ZnO波导薄膜。利用棱镜耦合、X射线衍射、RBS背散射分析等技术研究了所沉积薄膜的光波导及内部结构信息。结果表明：在两种衬底上所沉积的ZnO薄膜可以形成优良的平面光波导结构;薄膜结晶状况为存在少量其他晶向的C轴择优取向;薄膜含有的Zn及O组分原子数比例为近化学计量比;薄膜的沉积速率受衬底材料表面能作用轻微影响;薄膜的有效折射率较ZnO体材料小且受衬底材料影响。生长在蓝宝石衬底上ZnO薄膜的平均晶粒尺寸较在MgO衬底上的小,且其随膜厚的增加无明显变化,但在MgO衬底上晶粒尺寸则随膜厚的增加有增大趋势。     

ZnO films on transferable and low thermal resistance graphite substrate grown by ultrasonic spray pyrolysis

ZnO thin films were deposited on graphite substrates by ultrasonic spray pyrolysis method with Zn(CH 3 COO) 2 ·2H 2 O aqueous solution as precursor. The crystalline structure, morphology, and optical properties of the as-grown ZnO films were investigated systematically as a function of deposition temperature and growth time. Near-band edge ultraviolet(UV) emission was observed in room temperature photoluminescence spectra for the optimized samples, yet the usually observed defect related deep level emissions were nearly undetectable, indicating that high optical quality ZnO thin fi lms could be achieved via this ultrasonic spray pyrolysis method. Considering the features of transferable and low thermal resistance of the graphite substrates, the achievement will be of special interest for the development of high-power semiconductor devices with suffi cient power durability.     

Crystallization and conductivity mechanism of ITO films on different substrates deposited with different substrate temperatures

ITO thin films were grown on PC(polycarbonate), PMMA(polymethyl methacrylate) and glass substrates by r.f. magnetron sputtering. The electrical, structural and chemical characteristics of ITO films were analyzed by the Hall Technique, X-ray diffraction, and X-ray photoelectron spectroscopy. XPS studies suggest that all the ITO films consist of crystalline and amorphous phases. The degree of crystallinity increases from less than 45% to more than 90% when the substrate temperature increases from 80 to 300 ℃. The In and Sn exist in the chemical state of In3+ and Sn4+, respectively, independent of substrate type and temperature. The enrichment of Sn on surface and In in body of ITO films are also revealed. And, the oxygen deficient regions exist both in surface layer and film body. For ITO films deposited under 180 ℃ , the carrier concentration are mainly provided by oxygen vacancies, and the dominant electron carrier scattering mechanism is grain boundary scattering between the crystal and the amorphous grain. For ITO films deposited over 180 ℃, the carrier concentration are provided by tin doping, and the dominant scattering mechanism transforms from grain boundary scattering between the crystal grains to ionized impurity scattering with increasing deposition temperature.     

Development of Zr/ZrO<Subscript>2</Subscript> high temperature and high pressure sensors for <Emphasis Type="Italic">in-situ</Emphasis> measuring chemical parameters of deep-sea water

In order to in situ measure chemical parameters of deep-sea water and hydrothermal fluids at midocean ridge(MOR), it is necessary to use high temperature and high pressure chemical sensors.Developing new sensors is essential to measure in-situ pH and other chemical parameters(dissolved H2, dissolved H2S) of deep-sea water and hydrothermal fluids in a wide temperature range(2℃―400℃) at MOR vents.The YSZ(Yttria Stabilized Zirconia, 9%Y2O3) ceramic-based(HgO/Hg) chemical sensors possess excellent electrochemic...