PZT薄膜的MOD制备及形成机理研究

采用金属有机物热分解（ＭＯＤ）工艺在Ｐｔ／Ｔｉ／ＳｉＯ２／Ｓｉ衬底上制备锆钛酸铅（ＰＺＴ）薄膜。ＸＲＤ分析显示薄结晶状态良好,无焦绿石相存在。ＡＥＳ测量表明：薄膜成分沿膜厚均匀分布,膜中无碳存在,表面不富含铅。分析了薄膜的形成机理,安性地解释了晶粒的生长过程。     

溶胶-凝胶法制备PZT薄膜晶化过程的跟踪监测

用溶胶－凝胶技术制备了组成在准同型相界点［ｍ（Ｚｒ）／ｍ（Ｔｉ）＝５２／４８］附近的钙钛矿相ＰＺＴ薄膜,并运用原子力显微分析与椭偏法测试相结合的方法跟踪了薄膜的烧结过程．结果表明：钙钛矿相ＰＺＴ［ｍ（Ｚｒ）／ｍ（Ｔｉ）＝５２／４８］薄膜晶化发生于约５５０℃,并伴随着薄膜表面的粗糙化;镀铂硅基片表面粗糙度对ＰＺＴ薄膜的晶化有很大影响．根据ＡＦＭ,ＸＲＤ测试结果,分析了不同热处理条件对ＰＺＴ薄膜微结构及漏电流特性的影响,提出合适的热处理条件．分析了ＰＺＴ薄膜钙钛矿相形成温度高于相应粉体的原因     

Influence of strain on the dielectric properties of Bi–Zn–Ti–Nb–O solid solution thin films

Bi–Zn–Ti–Nb–O (BZTN) solid solution thin films with various compositions were prepared by metalorganic decomposition (MOD) process on the platinized Si substrates. BZTN thin films showed a wide solid solubility since the thin films maintained the single phase of cubic pyrochlore structure in a broad range of composition. Crystal structure and dielectric properties of BZTN thin films were compared to those of BZTN bulk ceramics and the difference in dielectric properties such as dielectric constant, dielectric loss and tunability between thin films and bulk ceramics were understood to originate from the strain in the thin films since there was no apparent difference in the other factors such as microstructure and preferred orientation. The existence of strain in the thin films was confirmed by two ways. One is the rate of lattice shrinking. Shrinkage in the lattice parameter of thin films was depressed compared to that of bulk ceramics, which might introduce the internal strain in the thin films. Another is the thermal expansion coefficient (α, TEC) of BZTN solid solutions. TEC measured from the bulk ceramics varied with composition and the difference in the TEC between the polycrystalline thin film and underlying substrate would result in the thermal strain of thin films. Thin films with various compositions were under different degree of tensile stress state and the BZTN thin films with optimal composition demonstrated the high tunability of 30% under 1100 kV/cm with dielectric constant of 242 and dielectric loss of 0.004.     

Effect of tantalum nitride supporting layer on growth and morphology of carbon nanotubes by thermal chemical vapor deposition

The role of tantalum nitride (TaNx) thin films as buffer layers on the control of nucleation and growth of aligned carpet-like carbon nanotubes (CNTs) has been proved. TaNx thin films have been deposited on Si by controlled magnetron sputtering process. Multiwall CNTs have been synthesized at 850 °C using an aerosol of ferrocene diluted in toluene. Electron microscopy images show a strong correlation between the growth rate and morphology of the CNTs and the initial composition of the TaNx thin films. Multi-scale investigations reveal that both morphology and structure of the CNTs are determined by the properties of the TaNx films. Raman and X-ray photoelectron spectroscopy, high resolution TEM imaging at the submicrometric and atomic scales have been used to confirm these hypotheses.     

Microstructure,Surface Morphology and Photoluminescence Properties of Al-Doped ZnO Thin Films Prepared by Plasma Focus Method

Al-doped ZnO (AZO), as one of the most promising transparent conducting oxide (TCO) materials, has now been widely utilized in thin film solar cells. In this research the optimization process of AZO thin films deposited by plasma focus device was carried out by investigation of its physical properties under different deposition conditions for its utilize as a front contact for the Cadmium Telluride (CdTe) based thin film solar cell applications. The effects of number of focus shots and angular position of substrate on the microstructure, surface morphology and photoluminescence properties of the thin films have been systematically studied. X-ray diffraction (XRD) study confirmed the polycrystalline nature of the all deposited AZO thin films. XRD analysis also revealed that crystal structure characteristics of obtained samples strongly depend on deposition conditions (number of shots and angular position). Scanning electron microscopy (SEM) and atomic force microscopy (AFM) analyses revealed the structure growth and enhancement of surface roughness, with increasing of focus shots or decreasing of angular position. From Photoluminescence (PL) emission spectra, the variations of structural defects and band gap energy for all the AZO thin films prepared under different deposition conditions were also discussed.     

Comprehensive characterization of CIGS absorber layers grown by one-step sputtering process

We have demonstrated that the use of a one-step sputtering process allowed for the fabrication of copper indium gallium diselenide (CIGS) thin films by RF magnetron sputtering without an additional selenization process. The CIGS thin films deposited at different substrate temperatures were synthesized on soda-lime glass (SLG) substrates using a single quaternary CIGS target. The film composition ratios of ([Cu]/[In]+[Ga]), ([Ga]/[In]+[Ga]), and ([Se]/[Cu]+[In]+[Ga]) were almost consistent with those of the sputtering target. X-ray diffraction (XRD) and Raman results showed that the crystallinity of the CIGS thin films was gradually improved as substrate temperatures increased. Transmission electron microscopy (TEM) showed that the films grown at 600?°C have a columnar structure with the grain size of ~100?nm. In addition, for the CIGS films grown at 600?°C, TEM-EDX analysis revealed that the synchronized fluctuation of the Cu and Se signals was observed in the direction of the film depth, while the In and Ga signals were constant. As a result, the CIGS solar cell made using the film showed a degraded cell efficiency of 2.5%, which might be have been caused by not only Cu-rich and Se-poor compositions but the locally unstable composition in the CIGS films fabricated by one-step sputtering.     

Synthesis and characterization of sol gel derived nontoxic CZTS thin films without sulfurization

Recently, great attention has been paid to the development of earth rich and nonhazardous Copper Zinc Tin Sulfide (CZTS–Cu₂ZnSnS₄) thin films for application in photovoltaic devices owing to its high absorption coefficient over the visible and infrared region. However, sulfurization process is an indispensable step in growing stoichiometric thin film using conventional physical vapor deposition. Hence, it is imperative to devise a liquid based technique without intentional sulfurization for the optimum quality growth of CZTS thin films. In the current work, layer-by-layer sol-gel deposition technique was utilized to grow high quality CZTS thin films without sulfurization and their structural and optical characteristics were investigated using XRD studies and UV-visible spectroscopy respectively. The morphology and chemical composition of the prepared CZTS films are estimated by scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) analysis respectively. Highly absorbing and crystalline CZTS films have been successfully grown in the present work which could be further utilized as an absorber layer in photovoltaic applications.     

Electroactive PVDF thin films fabricated via cooperative stretching process

Ferroelectric polymers have obtained much attention in low cost and flexible electronics. As one representative ferroelectric polymer, poly(vinylidene fluoride) (PVDF) has been comprehensively studied. Due to its complicated phase composition, fabrication of electroactive phases has been an open question especially for PVDF thin films deposited on solid substrates. Here cooperative stretching process is introduced for the fabrication of electroactive PVDF thin films. PVDF thin films are coated on stretchable poly(vinyl alcohol) substrates and mechanically stretched under optimized stretching parameters. Structural, spectral, and electrical measurements indicate that cooperative stretching process can effectively convert the nonpolar α phase to the electroactive β and γ phases companied by an enhancement of film crystallinity. Stretched PVDF films present a reverse piezoelectric coefficient of ?37 pm/V, comparable with the results from films fabricated by the other techniques. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46324.     

Electroplating of Fe-Ni alloys: Effects of sulphamic acid and sulphosalicylic acid

The electroplating of thin films of Fe–Ni alloys from acidic sulphate baths containing sulphamic acid and sulphosalicyclic acid has been studied under different plating conditions. The alloy composition varied with bath composition, current density and the concentrations of sulphosalicylic acid and sulphamic acid. Stirring of the bath solution enhanced the percentage of Fe in the alloy. The deposition potential became less noble with increase in the current density. Under some plating conditions, the plating system had a cathodic current efficiency greater than 90%. The coercivity values of the alloys were in the range 5–18 oersteds. From the X-ray analysis data f c c structure is assigned to the alloy films. Electroplating conditions have been optimized in order to obtain thin films of 20–80 Fe–Ni permalloy.     

Preparation and Electrical Properties of Lanthanum-Doped Lead Titanate Thin Films by Sol–Gel Processing

Lanthanum-doped lead titanate thin films have been prepared by sol–gel processing. These studies reveal the structural and electrical properties of 18 mol% La-doped PbTiO₃ thin films to be dependent on the annealing conditions. With appropriate annealing conditions, a relative dielectric constant of about 900 was obtained, comparable to the bulk composition.     

Role of solute and solvent on the deposition of ZnO thin films

ZnO thin films have been deposited on SnO₂:F coated transparent conducting oxide (TCO) glass substrates, using a simple electrochemical (galvanic) technique, from different electrolytic solutions. A detailed investigation on the effect of different solute and solvent on the deposition process has been made. We have established that galvanically obtained ZnO thin films can be deposited with various morphologies depending on the nature of the solute and solvent used. ZnO formation can happen either directly or through an intermediate mixed phase following different reaction paths. Structural, morphological, compositional and optical characterizations of the films developed under different conditions were carried out to study such effects. The films were also tested for their potential use as methane sensor.     

热处理对BiO_x薄膜的组成和结构的影响

采用反应磁控溅射法在氧气和氩气比例为20∶100的混合气体中制备了非化学计量的氧化铋薄膜。薄膜分别在真空和空气中400℃退火30min。采用X射线光电子能谱(XPS)和X射线衍射(XRD)研究了薄膜在真空和空气中退火对其组成和结构的影响。分析表明,在真空退火条件下薄膜中的金属铋和次氧化铋发生了相变,金属铋晶粒长大;而在空气中退火时薄膜主要发生了金属铋和次氧化铋的氧化过程,得到了四方Bi2O3。     

Growth mechanism of 3C-SiC(lll) on Si without carbonization process

We have used rapid thermal chemical vapor deposition (RTCVD) technique to grow epitaxial SiC thin films on Si wafers without carbonization process by pyrolyzing tetramethylsilane (TMS). The growth rate of SiC films increases with TMS flow rate and temperature, but it decreases with temperature at higher TMS flow rates. The XRD spectra of the films indicate that the growth direction is along the (111) direction of β-SiC. IR and RBS measurements have been employed to analyze the chemical composition of the films. At 1100°C TMS molecules dissociate almost completely into Si atoms, CH₄ and C₂H₂ gases. The growth mechanism of SiC films on Si substrates without carbonization process has been proposed based on the analyses by TEM and QMS.     

Preparation and Characterization Studies of Nanostructured CdO Thin Films by SILAR Method for Photocatalytic Applications

This work reports the preparation of cadmium oxide (CdO) thin films with different molar concentrations on glass substrate by simple and low cost SILAR (Successive Ionic Layer Adsorption and Reaction) method. The characterization, XRD pattern confirmed the presence of polycrystalline CdO in the deposited thin films with the cubic structure. The surface morphology and elemental composition of prepared thin films have been examined by scanning electron microscopy equipped with energy dispersive X-ray (EDX) analysis system. The optical property of the films was analyzed by UV–visible spectroscopy. The band gap of the deposited thin films was estimated by Tauc’s plot and it was found to be 2.6–2.8 eV. The prepared thin films were examined for the decomposition of the Methylene Blue (MB) dye which was visualized by UV-Visible spectroscopy, by decreasing the intensity of absorbance and concentration.     

Fabrication and properties of ZnO/GaN heterostructure nanocolumnar thin film on Si (111) substrate

Zinc oxide thin films have been obtained on bare and GaN buffer layer decorated Si (111) substrates by pulsed laser deposition (PLD), respectively. GaN buffer layer was achieved by a two-step method. The structure, surface morphology, composition, and optical properties of these thin films were investigated by X-ray diffraction, field emission scanning electron microscopy, infrared absorption spectra, and photoluminiscence (PL) spectra, respectively. Scanning electron microscopy images indicate that the flower-like grains were presented on the surface of ZnO thin films grown on GaN/Si (111) substrate, while the ZnO thin films grown on Si (111) substrate show the morphology of inclination column. PL spectrum reveals that the ultraviolet emission efficiency of ZnO thin film on GaN buffer layer is high, and the defect emission of ZnO thin film derived from Zn_i and V_o is low. The results demonstrate that the existence of GaN buffer layer can greatly improve the ZnO thin film on the Si (111) substrate by PLD techniques.     

Influence of process conditions on structural and electrochemical properties of lithium phosphorus oxynitride thin films

Lithium phosphorus oxynitride (LiPON) is the most representative solid electrolyte in thin film battery applications. In addition, it has been used as an interfacial protective layer to improve the stability of cathode and anode materials. In this article, we review the effect of the process conditions on the structural and electrochemical properties of LiPON thin films. A common method to form LiPON thin films is radiofrequency (RF) sputtering; much research has been conducted to optimize the corresponding process parameters, such as RF power density, working pressure in nitrogen atmosphere, substrate temperature, substrate bias power, post-annealing, and sputtering target. Many studies have characterized LiPON films obtained with various process parameters, but significant differences have been observed in the reported trends. The most representative difference involves the N_t/N_d ratio, which has been reported to be either directly or inversely proportional to the ionic conductivity. Recently, controversial results have been obtained on the N-based local structure of LiPON thin films. The structural argument relies on the idea that nitridation promotes cross-linking via the formation of doubly and triply coordinated N bridges between P atoms. In addition to further research to clarify these issues, it is necessary to introduce new methods for the interpretation of data based on it.     

SrTiO3薄膜的自组装生长

利用激光分子束外延技术在LaAlO3(100)单晶基片表面生长SrTiO3(STO)薄膜。通过反射式高能电子衍射原位实时监测STO薄膜自组装生长过程，采用原子力显微镜分析自组装生长演化过程，并利用X射线衍射分析薄膜结构及其生长方向。对不同生长条件下薄膜的生长的研究发现：在较低生长温度时，STO薄膜在(200)方向上以三维岛状模式进行生长，小岛在单位原胞尺度呈波浪状周期性排列，即出现自组装生长；而在较高的生长温度时，薄膜以层状模式进行生长自组装行为被抑止。并据此讨论了STO多元氧化物薄膜自组装生长条件及生长机理。     

Electrochromic properties of polycrystalline thin films of tungsten trioxide prepared by chemical vapour deposition

The electrochromic properties of polycrystalline thin films of tungsten trioxide prepared by chemical vapour deposition were studied using cyclic voltametry and chronoamperometry measurements. Two kinds of films were investigated depending on the conditions of preparation. Although the composition of the layers obtained after pyrolysis of W(CO)₆ is influenced by the presence of oxygen flow, the final annealing of these products leads to the same polycrystalline structure. Electrochromic properties have been investigated in acid and hydro-organic electrolytes. Cyclic voltametry shows that both colouration and bleaching of the films are associated with electrochemical reactions. The optical efficiencies and the response times were studied in both media and compared with amorphous WO₃ thin films prepared by vacuum evaporation. Best results have been obtained in acid electrolyte for films prepared by pyrolysis of W(CO)₆ in the presence of oxygen flow. We also observed that cycling greatly enhanced the response time. Current injection during colouration was found to depend strongly on time and to be mainly controlled by the resistance of the electrolyte at short times (f<200 ms).     

Electrodeposition of PbTe thin films from acidic nitrate baths

Electrodeposition of PbTe thin films from an acidic nitric bath was systematically investigated to understand the kinetics and the effect of electrodeposition conditions on film composition, crystallographic structure, texture and grain size. The electroanalytical studies employed initially with a rotating disk electrode to investigate the kinetics associated with Te, Pb and PbTe electrodeposition. The results indicated that the PbTe thin films were obtained by the underpotential deposition (UPD) of Pb atoms onto the overpotentially deposited Te atoms on a substrate.Based on these studies, PbTe thin films were potentiostatically electrodeposited using e-beam evaporated gold thin films on silicon substrate to investigate the effect of various deposition conditions on film composition and microstructure. The data indicated that the microstructure, composition and preferred film growth orientation of PbTe thin films strongly depended on the applied potential and electrolyte concentration. At −0.12 V, the film was granular, dense, and preferentially oriented in the [1 0 0] direction. At potentials more negative than −0.15 V, the film was dendritic and preferentially oriented in the [2 1 1] direction. A smooth, dense and crystalline film with nearly stoichiometric composition was obtained at −0.12 V from a solution containing 0.01 M HTeO₂⁺, 0.05 Pb²⁺ and 1 M HNO₃.     

Effect of adsorbed water vapor on Mg intercalation in electrochromic a-MoO3 films

The nature of interaction between the water vapor and MoO₃ thin films has been investigated using infrared spectroscopy technique. On prolonged exposure to high humidity conditions, presence of free water vapor and formation of Mo–OH bonds was detected in MoO₃ films. Films exposed to high humidity for various durations and freshly deposited were intercalated with Mg ions under identical experimental conditions. Free water vapor and Mo–OH bonds did not prevent/hinder the intercalation process. The diffusivity (D) of Mg ions in MoO₃ films has been estimated using Galvanostatic Intermittent Titration Technique (GITT) as a function Mg concentration. It is observed that D values are lesser in case of films exposed to humidity. Cyclic voltammetry studies carried out on films revealed reduced cyclability in exposed films compared to that of fresh films.