Ge掺杂二氧化钛复合薄膜制备及光吸收性能研究

采用磁控溅射和溶胶-凝胶两种方法在石英基体上制备了纯TiO2薄膜,并通过离子注入及溶胶掺杂方法分别对TiO2薄膜进行Ge掺杂改性。利用XRD、XPS及UV-Vis对两种TiO2复合薄膜的晶相结构、原子化学态以及光吸收性能进行了表征。结果表明,磁控溅射法制得TiO2薄膜为锐钛矿相,Ge离子注入引起复合薄膜的锐钛矿相消失,且该相600℃退火后并未得到恢复;经过退火后Ge在磁控溅射TiO2薄膜中以Ge单质存在。溶胶-凝胶法Ge掺杂复合薄膜中存在锐钛矿相TiO2和Ge晶相,Ge在薄膜表面以Ge和GeO2形式存在。两种掺杂方法制得的复合薄膜紫外-可见光吸收边均发生了红移。     

锐钛矿相TiO2纳米薄膜的制备及光致发光研究

以钛酸四丁酯ETi(O-BU)4]为前驱体,采用溶胶-凝胶法制备了锐钛矿相TiO2纳米薄膜。用X射线衍射(XRD)和光致发光(PL)光谱分别对不同烧结温度和不同手段(旋转涂敷法与一次摊涂法)制备的TiO2薄膜进行了表征。XRD分析表明TiO2薄膜的锐钛矿相(101)面上具有一定的择优取向。PL分析表明,在室温下,当用260nm激发TiO2薄膜时,在370～500nm范围内呈现出很宽的发光带,其对应着不同的发光中心;此外用545nm激发TiO2薄膜时,在近红外区域内818nm附近处展示出半高宽较宽且强度较强的发光峰。     

Optical characterization of titania thin films produced by the solgel method and doped with co(2+) at different concentrations

We report some preliminary results on the fabrication and optical characterization of high-refractive-index thin films of titania doped with Co(2+). These films were supported on silica platesthat were chemically activated to attach both phases. The titania films were produced by the solgel method at room temperature and slowly annealed from room temperature to 230 degrees C; their thickness was approximately 600 ?. The optical characterizations were obtained by the use of spectroscopic ellipsometry, where the dielectric function of the material was obtained as a function of the wavelength. Additionally, the ellipsometric function was modeled to obtain the porosity of the films and their thickness.     

Growth and characterization of AP-MOCVD iron doped titanium dioxide thin films

Atmospheric pressure metal organic chemical vapor deposition (AP-MOCVD) was used to prepare iron doped titanium dioxide thin films. Thin films, between 40 and 150 nm thick, were deposited on Si, SiO₂ and Al₂O₃ substrates using titanium tetra isopropoxide and ferrocene as metal organic precursors. TiO₂ iron doping was achieved in the range of 1–4 at.%. The film morphology and thickness, polycrystalline texture and doping content were studied using respectively scanning electron microscopy (SEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The influence of growth temperature, deposition time, substrate type and dopant partial pressure were studied. Electrical characterizations of the films were also performed.     

Deposition and characterization of highly p-type antimony doped ZnTe thin films

We report deposition of highly p-type antimony doped ZnTe films onto glass substrates using ZnTe and Sb effusion cells in ultra-high-vacuum environment of an MBE system. It was found that the widely-used conventional co-evaporation technique does not produce highly p-type films. Through a series of deposition experiments, a 4-step method consisting deposition of the layers followed by a post annealing process was developed. The maximum carrier concentration was 3 × 10¹⁹ cm⁻³ which is the highest reported for ZnTe:Sb films. The surface morphology and the structure of the films were analyzed using AFM and XRD. Electrical properties of Sb doped films were investigated by four-point probe and room temperature Hall effect measurements.     

Photo-degradation activity of sputter-deposited nitrogen-doped titania thin films

Various approaches have been reported during the last decade to enhance the photo-catalytic and super-hydrophilic characteristics of the intrinsic TiO₂ materials. Results on the photo-degradation activity of RF-sputtered nitrogen-doped titania thin films are presented here with respect to two environmental pollutants in gas- and liquid phases, as a function of dopant concentration. This study was accomplished by monitoring the time dependence of pollutant concentration in contact with the films, both under UV and solar light illumination. The synergic effects of surface morphology, crystalline and electronic structure of the materials are discussed in relation with the observed experimental facts. The results presented here show a close correlation between the oxidative power of the films and their previously reported wettability features.     

掺杂ZnO薄膜研究

采用电子束蒸发方法在玻璃衬底上制备ZnO薄膜和掺杂ZnO薄膜.通过X射线衍射、台阶仪及Hall效应等测试研究了衬底温度和掺杂对晶体质量和电学性能的影响,发现原位生长的ZnO薄沿c轴择优生长,且掺杂ZnO薄膜具有低达3.029×10-4Ω·cm的电阻率.     

Chemical bath deposition of indium sulphide thin films: preparation and characterization

Indium sulphide (In₂S₃) thin films have been successfully deposited on different substrates under varying deposition conditions using chemical bath deposition technique. The deposition mechanism of In₂S₃ thin films from thioacetamide deposition bath has been proposed. Films have been characterized with respect to their crystalline structure, composition, optical and electrical properties by means of X-ray diffraction, TEM, EDAX, optical absorption, TRMC (time resolved microwave conductivity) and RBS. Films on glass substrates were amorphous and on FTO (flourine doped tin oxide coated) glass substrates were polycrystalline ( phase). The optical band gap of In₂S₃ thin film was estimated to be 2.75 eV. The as-deposited films were photoactive as evidenced by TRMC studies. The presence of oxygen in the film was detected by RBS analysis.     

Low temperature atomic layer deposition of titania thin films

This paper presents a comprehensive study of atomic layer deposition of TiO₂ films on silicon and polycarbonate substrates using TiCl₄ and H₂O as precursors at temperatures in the range 80-120 °C. An in-situ quartz crystal microbalance was used to monitor different processing conditions and the resultant films were characterised ex-situ using a suite of surface analytical tools. In addition, the contact angle and wettability of as-deposited and UV irradiated films were assessed. The latter was found to reduce the contact angle from ≥ 80° to < 10°. Finally, the effect of surface pre-treatment on film toughness and adhesion was investigated and the results show a significant improvement for the pre-treated films.     

Characterization of titania thin films grown by dip-coating technique

A dip-coating technique was employed to prepare anatase phase of titania thin films. Fluorine doped tin oxide substrates were used to prepare titania thin films. The samples were annealed at 550 °C for 18 h. X-ray diffraction results revealed the amorphous and anatase phases of TiO₂ for as-synthesized and annealed samples, respectively. The crystallite size of anatase TiO₂ thin films was almost 25 nm for annealed samples. UV–visible confirmed the energy band gap 3.86 and 3.64 eV for as-prepared and calcinated titania thin films. The reduction in the energy band gap could be due to the change in crystallization and agglomeration of small grains after calcination. The morphology of the prepared films was investigated by field emission scanning electron microscopy which demonstrated the agglomeration of spherical particles of TiO₂ with average particle size of about 30 nm. The molecular properties (chemical bonding) of the samples were investigated by means of Fourier Transform Infrared (FTIR) spectroscopy. FTIR analysis exhibited the formation of titania, functional group OH, hydroxyl stretching vibrations of the C–OH groups, bending vibration mode of H–O–H, alkyl C–H stretch, stretching band of Ti–OH, CN asymmetric band stretching, and C=O saturated aldehyde.     

Preparation of titania covered multi-walled carbon nanotube thin films

The aim of this work was to investigate the effects of relative humidity on the formation of titania layers on the surface of multi-walled carbon nanotubes under regulated conditions in a sealed system. Reactive precursor compounds such as titanium (IV) oxychloride hydrochloric acid and titanium (IV) bromide were used as precursor to cover the surface of multi-walled carbon nanotubes (MWCNTs) under solvent conditions. The mixtures of MWCNTs and titania compounds were not stirred or sonicated. The effect of relative humidity was influenced using the mixture of sulphuric acid and water in desiccators. As-prepared titan-dioxide (TiO₂) layers were characterized by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), thermogravimetric analysis (TG), X-ray diffraction (XRD) and Raman spectroscopy. Our results revealed that TiO₂ layers with different thicknesses can be obtained using this simple sealed system. These TiO₂ covered multi-walled carbon nanotube films can be ideal candidates for different kinds of applications (e.g. sensors, virus filtration or catalysts).     

纳米晶TiO2薄膜的制备、表征及其光催化性能的研究

采用sol-gel法制备TiO2薄膜。用XRD、UV－vis、AFM对其结构、光谱吸收及表面形貌进行了表征。以具有典型偶氮染料结构的甲基橙水溶液为目标反应物，对膜的光催化性能进行了研究。结果表明，在普通玻璃衬底上得到了比较好的锐钛矿型TiO2薄膜，其紫外吸收谱带拓宽，该膜对低浓度甲基橙有较好的光催化降解功能。     

Chemical stability of doped ZnO thin films

We present the results of a chemical etching stability study carried out on ZnO thin films doped with several elements deposited by spray pyrolysis. Prior to the etching, a structural study was done by X-ray diffraction and the texture of the samples was obtained by scanning electron microscopy. The samples were etched employing a solution of dilute hydrochloric acid. The etching rates obtained for the different samples depend on the dopant element and our results confirm that films doped with Cr present the highest stability against chemical etching.     

Preparation and characterization of doped polyaniline films

Stable monolayer of the polyaniline doped with camphor sulfonic acid at the air-water interface has been obtained, of which multilayers have been successfully deposited by Langmuir–Blodgett technique onto CaF₂ substrate. The limiting mean molecular area and collapse pressure are found to be 0.294 nm² and 41 mN/m, respectively. The multilayers were characterized by IR and UV-Vis-NIR spectroscopies. X-ray small-angle diffraction data show that the multilayer was periodic layer structure with the layer spacing of 1.60 nm. The comparisons are also made with characterization of the casting film.     

High thermal stability thick wall mesoporous titania thin films

Mesoporous TiO₂ thin films were prepared by using tetrabutyl titanate as the inorganic precursor and triblock copolymer (Pluronic F127) as the structure directing agent. The obtained mesostructured TiO₂ thin film exhibits a high thermal stability, which can sustain 600 °C thermal treatment. The small angle XRD and wide angle XRD patterns indicate that the samples have mesoporous channel and are composed of anatase. The corresponding TEM images show that the homogeneous mesostructure and very thick pore walls (about 9–13 nm) are formed in the obtained thin films, which could be responsible for the high thermal stability of the framework. In addition, the samples have narrow pore diameter distribution and a mean pore size of 7.4 nm.     

Studies on preparation and characterization of indium doped zinc oxide films by chemical spray deposition

The preparation of indium doped zinc oxide films is discussed. Variation of structural, electrical and optical properties of the films with zinc acetate concentration and indium concentration in the solution are investigated. XRD studies have shown a change in preferential orientation from (002) to (101) crystal plane with increase in indium dopant concentration. Films deposited at optimum conditions have a low resistivity of 1.33 x 10^-4Ωm with 94% transmittance at 550 nm. SEM studies have shown smooth polycrystalline morphology of the films. Figure of merit is evaluated from electrical resistivity and transmittance data.     

Structures and properties of titania thin films annealed under different atmosphere

The effects of crystallinity, phase and oxygen vacancies on optical and photocatalytic properties of titania (TiO₂) thin films were systematically studied. The as-deposited amorphous titania films were prepared by reactive sputtering titanium metal targets in argon–oxygen plasma at 100 °C and subsequently annealed at various temperatures of 400–800 °C in air, vacuum and H₂ atmosphere. The results indicate that in general the crystallinity of the annealed films is enhanced with the increasing annealing temperature. At the same temperature, the H₂ annealed films achieve better crystallinity but containing more oxygen vacancies than the films annealed in air and in vacuum. In H₂ or in vacuum, the concentration of oxygen vacancies in the annealed films increases with increasing temperature, while in air it remains constant. Oxygen vacancies in titania film not only facilitate phase transformation but also lower the band gap of titania, and make the film visible-light responsive. Photocatalytic properties of the TiO₂ films were characterized in UV and visible light irradiation by following the Ag reduction and degradation of methylene blue. The films annealed at 600–700 °C in H₂ possess the best film crystallinity and the proper concentration of oxygen vacancies and exhibit the best photocatalytic performance under both UV and visible light.     

Superhydrophilicity and photocatalytic activity of sol-gel deposited nanosized titania thin films

Nanosized TiO₂ thin films with anatase structure were synthesized by a sol-gel dip coating method using TiCl₄-ethanol solution as a precursor. The resulting solution was aged between 0 up to 24 h and characterized by the X-ray diffraction, atomic force microscopy (AFM), and UV-vis photospectroscopy. The AFM reveals that aging time incites the grain growth of crystal in the TiO₂ films. The effect of aging time on morphology, photocatalytic, and superhydrophilic behavior of the films was also studied. It was found that there is an optimum aging time that photocatalytic and superhydrophilic yields reach a maximum, simultaneously. Photocatalytic and photo-wettability mechanisms follow two kinds of behaviors, depending on whether the aging time is less or more than a threshold value of around 1 h.     

TiO2-KTaO3复合薄膜制备与湿敏传感性质研究

通过溶胶凝胶法和旋涂法制备了单层和双层TiO2-KTaO3薄膜,并在不同的温度下退火1h,研究了该薄膜的湿敏传感特性.通过扫描电镜和X射线衍射研究了薄膜的形态特性,发现该薄膜具有纳米颗粒和毛细多孔结构.环境湿度变化从12%RH～97%RH的变化过程中,在500℃下退火的TiO2/KTaO3薄膜具有很高的灵敏度.对比单层薄膜,双层薄膜显示出有更大的电阻变化范围.还研究了TiO2/KTaO3薄膜的湿敏传感机理.     

Mn掺杂ZnO纳米材料的制备与性能研究

采用射频磁控溅射法在Si（100）衬底上沉积过渡族金属Mn掺杂的ZnO薄膜。将5％及7％原子比的MnO，与ZnO粉末充分混合后，加压制成靶材，通过改变溅射过程中的气氛和衬底温度沉积了Zn1-xMnxO薄膜。x射线衍射和场发射扫描电镜的分析表明：掺入≤7％的Mn原子不会改变薄膜的晶体结构，薄膜呈高度（002）晶面择优取向；薄膜表面均匀致密，颗粒尺寸约为30hm；Mn的掺入使薄膜的电学性能明显改善，但氧分压的使用或者Mn含量过大又会使薄膜的电阻率增加。