化学水浴沉积时间对CdS薄膜性质的影响

采用CBD法在醋酸镉溶液体系中制备CdS半导体薄膜,通过XRD、XRF、SEM和光学透过率谱等测试手段研究了沉积时间对CdS薄膜沉积过程和性质的影响.结果表明,随着沉积时间的增加,薄膜增厚;S/Cd原子比增加,但都为富Cd的CdS薄膜;XRD研究表明,薄膜结构由立方、六方混合相向立方相转变,(111)方向成为择优生长方向;SEM研究表明,随沉积时间增加,薄膜变致密,薄膜表面出现的白色附着颗粒增多,尺寸增大;沉积时间对薄膜的光学性质也有很大的影响,随着沉积时间的增加薄膜透过率减小,而禁带宽度值增大.     

Deposition of ZnS thin films by photochemical deposition technique

ZnS thin films have been deposited on a glass substrate by photochemical deposition (PCD) technique from an aqueous solution. The effect of pH and stirring speed of the solution on deposition has been studied. The optical transmission spectra of the solutions have been recorded before and after deposition and also for the deposited film. The as-deposited and annealed films were characterized by X-ray diffraction (XRD) and it is observed that the crystallinity of the deposited films is improved by annealing at various temperature from 100 to 500 °C. The surface coverage of the film has been studied using optical microscope.     

Structural studies on some doped CdS thin films deposited by thermal evaporation

The influence of the Mn, Se and Sb impurities on the structure and morphology of CdS thin films grown on p⁺ Si wafers was studied. The starting powders were mixed in the same molar ratios (0.3%) and deposited in the same conditions by vacuum thermal evaporation. X-ray diffraction(XRD), X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM) and reflectance studies made on thermal treated thin films (573 K, 2 h in air) evidenced that thin films have a hexagonal oriented structure, and that dopants enter into the CdS lattice merely by substitution. The dopant nature influences the thin film thickness and chemical composition. The doped CdS thin films have roughness in nanometer region and a reflectivity lower than 40%. Silicon substrate acts as a template and favors the retention of Mn and scatters the Sb dopants. The CdS:Se thin film is thicker than CdS:Mn and CdS:Sb ones and is a mixture of doped and undoped nanocrystals.     

The effect of sulfur concentration on the properties of chemical bath deposited CdS thin films

We study the structural, surface morphology and optical properties of chemical bath deposited (CBD) cadmium sulfide (CdS) thin films under the effect of variation of S/Cd ratio. CdS thin films have been successfully deposited by CBD technique with solutions containing S/Cd ionic concentration ratio of 5.0, 2.5, 1.0, 0.5 and 0.25. Single phase CdS, with a hexagonal structure, is observed for the concentration of S/Cd = 5.0, 2.5, 1.0 and 0.5 films while for the ratio of 0.25, the films exhibited a partially amorphous nature. These have been confirmed by X-ray diffraction (XRD), transmission and scanning electron microscopy (TEM and SEM) analyses. The band gaps of the films obtained by transmission and photoacoustic spectra are found to be in the range of 2.40 to 3.26 eV. The large variation of band gaps of the films with composition is discussed by employing quantum size effect phenomena. The transition levels of CdS are also studied using photoacoustic spectroscopy.     

用网状阴极法在碳钢表面沉积氮化钽薄膜

介绍了一种新型的在钢铁基体上制备氮化钽薄膜的方法－－网状阴极法。其设备简单、价格低廉。试验中发现，在各个参数配比合适的条件下，可制备出结构为fcc(面心立方）和hex（密排六方）的氮化钽薄膜。薄膜较致密且均匀，与其体的结合好。同时分析了在最佳工艺参数条件下合成氮化钽膜的成分、组织、表面、断口形貌和结合力等。该方法为氮化钽薄膜作为结构材料使用提供了一种新的途径。     

Effects of different needles and substrates on CuInS2 deposited by electrostatic spray deposition

Copper indium disulphide (CuInS₂) thin films were deposited using the electrostatic spray deposition method. The effects of applied voltage and solution flow rate on the aerosol cone shape, film composition, surface morphology and current conversion were investigated. The effect of aluminium substrates and transparent fluorine doped tin oxide (SnO₂:F) coated glass substrates on the properties of as-deposited CuInS₂ films were analysed. An oxidation process occurs during the deposition onto the metallic substrates which forms an insulating layer between the photoactive film and substrate. The effects of two different spray needles on the properties of the as-deposited films were also studied. The results reveal that the use of a stainless steel needle results in contamination of the film due to the transfer of metal impurities through the spray whilst this is not seen for the glass needle. The films were characterised using a number of different analytical techniques such as X-ray diffraction, scanning electron microscopy, Rutherford back-scattering and secondary ion mass spectroscopy and opto-electronic measurements.     

The effects of substrate and annealing on structural and electrochemical properties in LiCoO2 thin films prepared by DC magnetron sputtering

LiCoO2 thin films were fabricated by direct current magnetron sputtering method on STS304 and Ti substrates. The effects of substrate and annealing on their structural and electrochemical properties of LiCoO2 thin film cathode were studied. Crystal structures and surface morphologies of the deposited films were investigated by X-ray diffraction and field emission scanning electron microscopy. The as-deposited films on both substrates have amorphous structure. The (104) oriented perfect crystallization was obtained by annealing over 600 degrees C in STS304 substrate. The LiCoO2 thin film deposited on Ti substrate shows the (003) texture after annealing at 700 degrees C. The electrochemical properties were investigated by the cyclic voltammetry and charge-discharge measurement. The 600 degrees C-annealed LiCoO2 film deposited on STS304 substrate exhibits the inithial discharge capacity of 22 uAh/cm2 and the 96% capacity retention rate at 50th cycles. The electrochemical measurement on annealed films over 600 degrees C was impossible due to the formed TiO2 insulator layer using Ti substrate. As a result, it was found that the STS304 substrate seems to be more suitable material than the Ti substrate in fabricating LiCoO2 thin film cathode.     

ZnO thin film sensors for detecting dimethyl- and trimethyl-amine vapors

Undoped and Al-doped ZnO thin films were deposited on quartz substrates using an indigenously developed modified chemical vapor deposition technique. Microstructures of the deposited films were optimized by adjusting various growth parameters. The baseline resistance of the ZnO film sensors was stabilized by annealing the as-deposited films periodically in an oxidizing and reducing ambient at maximum operating temperature. The sensor parameters were studied by exposing the optimized ZnO thin films to low concentrations of dimethylamine (DMA) and trimethylamine (TMA), the chemical species released from harvested fish and other seafood with ageing. The effect of operating temperature was found to play a vital role in determining the sensitivity and resolution of the sensor. While the undoped ZnO film surface, sensitized with palladium, exhibited higher DMA sensitivity than that of TMA, an enhanced TMA sensitivity was noticed with the ZnO films doped with aluminum.     

An in-situ chemical reaction deposition of nanosized wurtzite CdS thin films

Nanocrystalline CdS thin films were deposited on glass substrates by an ammonia-free in-situ chemical reaction synthesis technique using cadmium cationic precursor solid films as reaction source and sodium sulfide based solutions as anionic reaction medium. Effects of ethanolamine addition to the cadmium cationic precursor solid films, deposition cycle numbers and annealing treatments in Ar atmosphere on structure, morphology, chemical composition and optical properties of the resultant films were investigated by X-ray diffraction, field emission scanning electron microscope, energy dispersive X-ray analysis and UV-Vis spectra measurements. The results show that CdS thin films deposited by the in-situ chemical reaction synthesis have wurtzite structure with (002) plane preferential orientation and crystallite size is in the range of 16 nm-19 nm. The growth of film thickness is almost constant with deposition cycle numbers and about 96 nm per cycle.     

CdS thin films growth by ammonia free chemical bath deposition technique

Cadmium Sulfide CdS thin films were deposited by chemical bath deposition technique using ethanolamine as complexing agent instead of commonly used ammonia to avoid its toxicity and volatility during film preparation. In order to investigate the film growth mechanism samples were prepared with different deposition times. A set of substrates were dropped in the same bath and each 30 minutes a sample is withdrawn from the bath, by this way all the obtained films were grown in the same condition. The films structure was analyzed by X rays diffraction. In early stage of growth the obtained films are amorphous, with increasing the deposition time, the films exhibits a pure hexagonal structure with (101) preferential orientation. The film surface morphology was studied by atomic force microscopy. From these observations we concluded that the early growth stage starts in the 3D Volmer-Weber mode, followed by a transition to the Stransky-Krastanov mode with increasing deposition time. The critical thickness of this transition is 120 nm. CdS quantum dots were formed at end of the film growth. The optical transmittance characterization in the UV-Visible range shows that the prepared films have a high transparency ranging from 60 to 80% for photons having wavelength greater than 600 nm.     

Influence of deposition temperature on structure and morphology of nanostructured SnO2 films synthesized by pulsed laser deposition

Nanostructured tin oxide thin films were deposited on the Si (100) substrate using the pulsed laser deposition technique at different substrate temperatures (300, 450 and 600 °C) in an oxygen atmosphere. The structure and morphology of the as-deposited films indicate that the film crystallinity and surface topography are influenced by the deposition temperature by changing from an almost amorphous to crystalline microstructure and smoother topography at a higher substrate temperature. The photoluminescence measurement of the SnO₂ films shows three stable emission peaks centered at respective wavelengths of 591, 554 and 560 nm with increasing deposition temperature, contributed by the oxygen vacancies.     

磁控溅射法制备的CdS:Al薄膜的性质研究

采用Al和CdS双靶共溅射的方法, 调控Al和CdS源的沉积速率, 制备出不同Al掺杂浓度的CdS:Al薄膜。通过XRD、SEM、AFM、紫外-可见透射光谱分析、常温霍尔测试对CdS: Al薄膜的结构、形貌、光学和电学性质进行表征。XRD结果表明, 不同Al掺杂浓度的CdS:Al薄膜均为六方纤锌矿结构的多晶薄膜, 并且在(002)方向择优生长。SEM和AFM结果表明, CdS:Al薄膜的表面均匀致密, 表面粗糙度随着Al掺杂浓度的增加略有增加。紫外-可见透射光谱分析表明, CdS:Al薄膜禁带宽度在2.42~2.46 eV 之间, 随着Al掺杂浓度的增加而略微减小。常温霍尔测试结果证明, 掺Al对CdS薄膜的电学性质影响显著, 掺Al原子浓度3.8%以上的CdS薄膜, 载流子浓度增加了3个数量级, 电阻率下降了3个数量级。掺Al后的CdS薄膜n型更强, 有利于与CdTe形成更强的内建场, 从而提高太阳电池效率。用溅射方法制备的CdS:Al薄膜的性质适合用作CdTe薄膜太阳电池的窗口层。     

Sc2W3O12薄膜制备及其负热膨胀性能

采用脉冲激光沉积法制备了斜方相Sc₂W₃O₁₂薄膜。利用X射线衍射仪(XRD)和场发射扫描电镜(FESEM)对Sc₂W₃O₁₂靶材和Sc₂W₃O₁₂薄膜组分、表面形貌和靶材断面形貌进行表征, 研究衬底温度与氧分压对薄膜制备的影响。采用变温XRD和热机械分析仪(TMA)分析了Sc₂W₃O₁₂陶瓷靶材和薄膜的负热膨胀特性。实验结果表明: 经1000℃烧结6 h得到结构致密的斜方相Sc₂W₃O₁₂陶瓷靶材, 其在室温到600℃的温度范围内平均热膨胀系数为-5.28×10^-6 K^-1。在室温到500℃衬底温度范围内脉冲激光沉积制备的Sc₂W₃O₁₂薄膜均为非晶态, 随着衬底温度的升高, 薄膜表面光滑程度提高; 随着沉积氧压强增大, 表面平整性变差。非晶膜经1000℃退火处理7 min后得到斜方相Sc₂W₃O₁₂多晶薄膜, 在室温到600℃温度区间内, Sc₂W₃O₁₂薄膜的平均热膨胀系数为-7.17×10^-6 K^-1。     

Correlation study between structural, magnetic and transport properties of annealed Co thin films

This paper presents structural, magnetization and transport properties measurements carried out on as-deposited Co (400 Å) thin film as well as samples annealed in the temperature range 100-500 °C in steps of 100 °C for 1 h. The samples used in this work were deposited on float glass substrates using ion beam sputtering technique. The magnetization measurements carried out using MOKE technique, clearly indicates that as-deposited as well as annealed samples up to 500 °C show well saturation magnetization with applied magnetic field. The as-deposited sample shows coercivity value (H_c) of 26 Oe, and it is increased to 94 Oe for 500 °C-annealed sample. A minimum coercivity value of 15 Oe is obtained for 200 °C annealed sample. The XRD measurements of as deposited films show microcrystalline nature of Co film, which becomes crystalline with increase in annealing temperature. The corresponding resistivity measurements show gradual decrease in resistivity. AFM technique was employed to study the surface morphology of as deposited film as well as annealed thin films. Observed magnetization, and resistivity behaviour is mainly attributed to the (i) change in crystal structure (ii) increase in grain size and (iii) stress relaxation due to the annealing treatment.     

X-ray line broadening and photoelectrochemical studies on CdSe thin films

Cadmium Selenide (CdSe) thin films have been prepared on Indium doped tin oxide coated conducting glass (ITO) substrates at various deposition potential and solution pH values using potentiostatic cathodic electrodeposition technique. The deposited films are characterized using X-ray diffraction, scanning electron microscopy, energy dispersive analysis by X-rays, optical absorption, and photoelectrochemical techniques, respectively. X-ray diffraction pattern revealed that the deposited films are found to exhibit hexagonal structure with preferential orientation along (002) plane. X-ray line profile analysis technique by the method of variance has been used to evaluate the microstructural parameters such as crystallite size, rms microstrain, dislocation density, and stacking fault probability. The variation of microstructural parameters with deposition potential, solution pH values, and annealing temperature are studied. Surface morphology and film composition are investigated by scanning electron microscopy and energy dispersive analysis by X-rays, respectively. Optical absorption analysis has been carried out to evaluate the optical parameters such as refractive index, extinction coefficient, real and imaginary dielectric constants, and packing density, respectively. Photoelectrochemical solar cells are constructed using as-deposited and annealed CdSe thin films as photocathode, and their power output characteristics are studied. The experimental observations are discussed in detail.     

Dielectric properties of DC reactive magnetron sputtered Al2O3 thin films

Alumina (Al₂O₃) thin films were sputter deposited over well-cleaned glass and Si < 100 > substrates by DC reactive magnetron sputtering under various oxygen gas pressures and sputtering powers. The composition of the films was analyzed by X-ray photoelectron spectroscopy and an optimal O/Al atomic ratio of 1.59 was obtained at a reactive gas pressure of 0.03 Pa and sputtering power of 70 W. X-ray diffraction results revealed that the films were amorphous until 550 °C. The surface morphology of the films was studied using scanning electron microscopy and the as-deposited films were found to be smooth. The topography of the as-deposited and annealed films was analyzed by atomic force microscopy and a progressive increase in the rms roughness of the films from 3.2 nm to 4.53 nm was also observed with increase in the annealing temperature. Al-Al₂O₃-Al thin film capacitors were then fabricated on glass substrates to study the effect of temperature and frequency on the dielectric property of the films. Temperature coefficient of capacitance, AC conductivity and activation energy were determined and the results are discussed.     

Preparation and characterization of amorphous manganese sulfide thin films by SILAR method

Manganese sulfide thin films were deposited by a simple and inexpensive successive ionic layer adsorption and reaction (SILAR) method using manganese acetate as a manganese and sodium sulfide as sulfide ion sources, respectively. Manganese sulfide films were characterized for their structural, surface morphological and optical properties by means of X-ray diffraction, scanning electron microscopy, energy dispersive X-ray analysis and optical absorption measurement techniques. The as-deposited film on glass substrate was amorphous. The optical band gap of the film was found to be thickness dependent. As thickness increases optical band gap was found to be increase. The water angle contact was found to be 34°, suggesting hydrophilic nature of manganese sulfide thin films. The presence of Mn and S in thin film was confirmed by energy dispersive X-ray analysis.     

Atomic force microscopy and X-ray photoelectron spectroscopy evaluation of adhesion and nanostructure of thin Cr films

Chromium (Cr) thin films were deposited on float glass using electron beam (e-beam) physical vapor deposition and radio frequency (RF) magnetron sputtering techniques. Surface morphology of these Cr films was studied using atomic force microscopy (AFM). The e-beam deposited Cr films consisted of isolated surface mounds while in RF sputtered samples, these mounds combined to form larger islands. Lower surface adhesive properties were observed for e-beam deposited films, as determined from AFM force-distance curves, presumably due to the nanostructural differences. Similar amounts of adsorbed atmospheric carbonaceous contaminants and water vapor were detected on samples deposited using both methods with e-beam deposited samples having additional carbide species, as determined by X-ray photoelectron spectroscopy data. The dominant crystallographic plane in both e-beam deposited and RF sputtered Cr thin films was (110) of body-centered cubic Cr metal structure as determined from X-ray diffraction data. Weak (211) reflection was also observed in RF sputtered samples and was attributed to a different thin Cr film condensation and growth mechanism which resulted in nanostructural differences between films deposited using two different methods.     

Structural study of thin MgO layers on Ag(001) prepared by either MBE or sputter deposition

Growth, morphology and structure of thin MgO films prepared on Ag(001) substrates by different preparation procedures have been investigated by AES, LEED and modulated electron emission. Oxide layers were prepared by Mg MBE in an oxygen atmosphere or sputter deposition from bulk MgO target. In both cases stoichiometric MgO forms, which initially grows in a rocksalt tetragonally distorted structure. For 3-ML films, 3.6% expansion of the interlayer spacing along the growth axis has been measured. The misfit strain progressively reduces as the film thickness increases, and the equilibrium spacing is completely recovered at 8–10 ML thickness. In spite of the similarity in structure and strain, different deposition procedures lead to different film morphology. Sputter deposited films only partially cover the substrate. Fractional coverage (50%) has been evaluated for the 3-ML thick film, and full coverage only occurs at approximately 10 ML thickness. The MBE procedure results in almost complete layers. Fourfold broadening of spot profiles has been observed in LEED patterns of both MBE and sputter deposited films, indicating the occurrence of a similar large-scale atomic arrangement and surface morphology.     

Dy掺杂的CdS薄膜的制备及性能分析

采用化学水浴法在玻璃衬底上制备纯的和稀土Dy掺杂的CdS薄膜,并在N2气氛中,对以上制备的薄膜进行T=350℃、t=40min的热处理.实验结果表明,水浴温度在70℃～80℃间制备的CdS薄膜,表面致密、光滑,膜的质量最好,且为沿[111]晶向择优生长的立方闪锌矿结构.掺Dy虽未改变CdS薄膜的晶体结构,但改善了薄膜的表面形貌,使得薄膜的致密性增强、颗粒大小匀称,同时Dy的掺入增大了CdS薄膜在可见光范围内的透光率.