掺磷四面体非晶碳薄膜电极的电化学伏安特性

采用过滤阴极真空电弧技术, 以高纯磷烷气体为掺杂源制备掺磷四面体非晶碳(ta-C:P)薄膜. 利用X射线光电子能谱和激光拉曼光谱表征薄膜的成分和结构, 采用循环伏安和微分脉冲伏安分析薄膜的电化学行为. 结果表明, 磷的掺入没有引起薄膜非晶结构的明显变化, 只是促进了sp²杂化碳原子的团簇. 经过酸预处理的ta-C:P薄膜在硫酸溶液中有宽的电势窗口和低的背景电流; 对Cl^-有催化活性; 薄膜表面电子传输速度快; 对水溶液中Cu²⁺和Cd²⁺有检测活性. 因此具有良好导电性的ta-C:P薄膜适于作为电极并有望用于污水中重金属离子的分析检测等领域.     

硅衬底Al2O3∶Tb3+薄膜的制备及其发光性能

采用溶胶凝胶法在硅衬底上制备了Al₂O₃∶Tb³⁺薄膜; 并采用DTA-TG、XRD、SEM、AFM及光致发光光谱对其进行了一系列表征; 分析了Al₂O₃∶Tb³⁺薄膜的发光机理, 探讨了热处理温度和Tb³⁺掺杂浓度对发光性能的影响规律. 研究结果表明, 采用溶胶凝胶法制备工艺, 制备了高发光强度的Al₂O₃∶Tb³⁺薄膜, 薄膜的最佳激发波长为240nm, Tb³⁺的最佳掺杂浓度为5mol%(Tb₂O₃/Al₂O₃=5mol%), 在240nm光激发下, 最强的发射峰出现在544nm附近; 并且制备的Al₂O₃∶Tb³⁺薄膜表面致密、平整且无裂纹产生, 表面粗糙度约为1.3nm, 有利于硅基光电子器件的制备和应用.     

锂离子注入对V2O5薄膜红外振动特性影响

用反应蒸发法制备了多晶Ｖ２Ｏ５薄膜,采用两电极多锂离子电解质向Ｖ２Ｏ５薄膜注入锂离子,测试了离子注入前后薄膜的红外反射光谱,实验结果表明,锂离子注入对Ｖ２Ｏ５晶体红外振动影响较大。采用多晶Ｖ２Ｏ５振动模型分析了薄膜的红外振动吸收,并得到了锂离子注入产生的Ｖ２Ｏ５薄膜振动的变化是由于晶格扩展和钒离子自身杂质形成引起的。     

真空蒸发法制备PbI2多晶薄膜研究

用真空蒸发法在玻璃衬底上制备了PbI₂多晶薄膜,对样品的微结构、表面形貌、化学组分及电阻率进行了测试分析.结果表明,样品具有良好的多晶结构,并沿六角密堆积结构的c轴向高度择优取向.室温下样品暗电导率为3.09×10^-11(Ω·cm)^-1,电导激活能为0.78eV.     

射频反应溅射氧化铌薄膜的电致变色性能研究

采用射频反应溅射法成功地制备了非晶态氧化铌薄膜,研究了它们的电致变色性能．这些薄膜在漂白态透明无色,而着色态则为灰褐色．循环伏安测试结果表明该薄膜具有良好的稳定性和很好的锂离子注入/抽出性能．５５０ｎｍ处的着色效率为１６．６８ｃｍ^２/Ｃ,在可见光区透过率调制幅度为２０%~３０%．结合Ｘ光电子能谱(ＸＰＳ)分析可以认为氧化铌薄膜的电致变色现象是由于锂离子和电子的共同注入与抽出,导致薄膜中的铌离子发生Ｎｂ^Ｖ和Ｎｂ^ＩＶ间的可逆氧化、还原反应引起的．     

AlSb多晶薄膜材料的性能研究

采用共蒸法制备了新型AlSb多晶薄膜. 通过XRF、XRD、Hall测试及电导率温度关系等研究了AlSb多晶薄膜的组分、结构及性能. 分析表明,刚沉积的AlSb薄膜为非晶相,在540℃以上退火转变为AlSb相,转变的程度取决于退火的温度及Al、Sb的原子配比,其中N_Al∶N_Sb为47.2∶52.8,580℃退火后的薄膜多晶转变最为明显,结晶度较高;测试结果表明,退火后的AlSb薄膜为p型间接带隙半导体,载流子浓度为10¹⁹cm^-1,吸收系数为10⁴,而且在升降温阶段电导率发生不可逆变化. 这种薄膜用于TCO/CdS/AlSb结构的太阳电池器件中已经得到200mV左右的开路电压.     

碳纳米管和镓掺杂碳纳米管场发射性能研究

采用催化热解方法分别 制备出碳纳米管和镓掺杂碳纳米管, 并利用丝网印刷工艺将其制备成纳米管薄膜. 对此薄膜进行低场致电子发射测试表明, 碳纳米管和镓掺杂纳米管开启电场分别为2.22和1.0V/μm, 当外加电场为2.4V/μm, 碳纳米管发射电流密度为400μA/cm², 镓掺杂纳米管发射电流密度为4000μA/cm². 可见镓掺杂碳纳米管的场发射性能优于同样条件下未掺杂时的碳纳米管. 对镓掺杂纳米管场发射机理进行了探讨.     

Bi2-xSbxTe3温差电材料薄膜的电化学制备、表征及性能研究

采用电化学控电位沉积的方法制备了Bi_2-xSb_xTe₃温差电材料薄膜.通过ESEM、XPS、XRD、EDS等方法对电沉积薄膜的形貌、结构和组成进行了研究,并测试了在不同电位下制备的Bi_2-xSb_xTe₃薄膜的温差电性能.研究结果表明,在含有Bi³⁺、HTeO₂⁺和SbO⁺的溶液中,采用控电位沉积模式,可实现铋、锑、碲三元共沉积,生成锑掺杂的Bi₂Te₃化合物Bi_2-xSb_xTe₃.通过调节沉积电位,可控制电沉积Bi_2-xSb_xTe₃薄膜的掺杂浓度,从而影响材料的温差电性能.控制沉积电位为-0.5V条件下制备的温差电材料薄膜的塞贝克系数最大,为213μV·K^-1,其组成为Bi_0.5Sb_1.5Te₃.随着沉积电位的负移,电沉积出的Bi_2-xSb_xTe₃薄膜的结晶状态将逐渐由等轴晶转变为树枝晶.研究证明,电沉积方法可以制备出性能优异的薄膜温差电材料.     

喷雾热解法生长N掺杂ZnO薄膜机理分析

通过超声喷雾热解工艺,以醋酸锌和醋酸铵的混合水溶液为前驱溶液,在单晶Si(100) 衬底上制备了N掺杂ZnO薄膜,采用热质联用分析(TG—DSC—MS)、X射线衍射(XRD)、场发射扫描电镜(FESEM)和霍耳效应(Hall-effect)测试等手段研究了喷雾热解工艺下N掺杂ZnO薄膜的生长机理、晶体结构和电学性能.结果表明,随衬底温度的不同,薄膜呈现出不同的生长机理,从而影响薄膜的晶体结构和电学性能.在优化的衬底温度下,实现了ZnO薄膜的p型掺杂,得到的p型ZnO薄膜具有优异的电学性能,载流子浓度为3.21×10¹⁸cm^-3,霍耳迁移率为110cm²·V^-1s^-1,电阻率为1.76×10^-2Ω·cm.     

BaxSr1-xTiO3前驱多层膜制备及后热处理条件的优化

用Ar^~+离子束多靶溅射沉积技术在单晶硅Si(100)上顺序沉积了TiO₂、BaCO₃、SrCO₃叠层,并经后期低温扩散和高温晶化两步热处理过程制备了Ba_xSr_1-xTiO₃薄膜。用俄歇扫描电子能谱(AES)对其低温扩散效应(温度、时效、沉积顺序)进行了研究。实验结果表明:在低温段长时间保温或在中温段短时间保温都有利于各沉积组元充分扩散,扩散均匀的混合膜层经高温晶化(900℃)能形成多晶Ba_xSr_1-xTiO₃薄膜。     

Crystallization of chemically vapor deposited molybdenum and mixed tungsten/molybdenum oxide films for electrochromic application

The paper deals with investigation of Mo oxide and mixed W/Mo oxide films showing high electrochromic performance. Films are deposited on Si and conductive glass substrates using pyrolytical decomposition at 200 °C of Mo and W hexacarbonyls in Ar/O₂ atmosphere. The study is focused on structural transformation of the films in dependence on deposition and annealing process parameters. In case of conductive glass substrate (typical for electrochromic devices), the crystallization process in Mo oxide films is almost completed at 400 °C forming triclinic MoO_2.89 and orthorhombic MoO₃ crystalline phases. The structure of mixed W/Mo oxide films is triclinic crystalline phase of tungsten oxide matrix with Mo atoms as substitutes. Discussed are, as well, differences in the crystallization process for the same films, when the substrate is Si. All the films show electrochromic effect, the mixed W/Mo oxide films expressing stronger electrochromic effect with superior color efficiency and optical modulation.     

Hot-wire chemical vapor deposition of WO3−x thin films of various oxygen contents

We present the synthesis of tungsten oxide (WO_3−x) thin films consisting of layers of varying oxygen content. Configurations of layered thin films comprised of W, W/WO_3−x, WO₃/W and WO₃/W/WO_3−x are obtained in a single continuous hot-wire chemical vapor deposition process using only ambient air and hydrogen. The air oxidizes resistively heated tungsten filaments and produces the tungsten oxide species, which deposit on a substrate and are subsequently reduced by the hydrogen. The reduction of tungsten oxides to oxides of lower oxygen content (suboxides) depends on the local water vapor pressure and temperature. In this work, the substrate temperature is either below 250 °C or is kept at 750 °C. A number of films are synthesized using a combined air/hydrogen flow at various total process pressures. Rutherford backscattering spectrometry is employed to measure the number of tungsten and oxygen atoms deposited, revealing the average atomic compositions and the oxygen profiles of the films. High-resolution scanning electron microscopy is performed to measure the physical thicknesses and display the internal morphologies of the films. The chemical structure and crystallinity are investigated with Raman spectroscopy and X-ray diffraction, respectively.     

Atomic layer deposition of tungsten using sequential surface chemistry with a sacrificial stripping reaction

Tungsten (W) films were grown with atomic layer control using a novel sequence of self-limiting surface reactions. The tungsten film growth was achieved by dividing the binary reaction WF₆+Si₂H₆→W+2SiHF₃+2H₂ into two separate half-reactions. Alternating exposures to WF₆ and Si₂H₆ in an ABAB… sequence produced tungsten deposition at temperatures between 425 and 600 K. The Si₂H₆ reactant served only a sacrificial role to strip fluorine from tungsten without incorporating into the film. FTIR spectroscopic investigations demonstrated that the WF₆ and Si₂H₆ half-reactions were complete and self-limiting at T>400 K. In situ spectroscopic ellipsometry measurements determined a tungsten growth rate of 2.5 Å/AB cycle with WF₆ and Si₂H₆ reactant exposures sufficient for complete half-reactions. The surface topography of the deposited tungsten films was flat indicating smooth film growth. The tungsten films were either amorphous or composed of very small crystalline grains and contained no measurable silicon or fluorine. These results represent the first demonstration of atomic layer deposition of smooth single-element metal films using sequential surface chemistry.     

Effect of tungsten on the electrochromic behaviour of sol-gel dip coated molybdenum oxide thin films

The paper describes the results obtained on the performance of Mo oxide and mixed W/Mo oxide thin films for possible electrochromic applications. Mo and W/Mo oxide films were deposited on conductive (FTO) glass substrates using sol-gel dip coating method. The films were annealed at 250 °C for 30 min. The structure and morphology of Mo and W/Mo oxide films were examined using XRD, SEM and EDS. XRD results indicate the amorphous nature of the Mo and W/Mo oxide films annealed for 30 min. The CV measurements revealed that the films prepared with 10 wt.% of tungsten exhibit maximum anodic/cathodic diffusion coefficient of 24.99/12.71 × 10⁻¹¹ cm²/s. The same film exhibits a maximum transmittance variation (ΔT%) of 83.4% at 630 nm and 81.06% at 550 nm with the optical density of 1.00 and 1.13 respectively.     

Electrochromic behavior of CVD molybdenum oxide and Mo-W mixed-oxide thin films

Thin films of molybdenum oxide, tungsten oxide, and mixed Mo-W oxide were prepared by atmospheric-pressure chemical vapor deposition. For all films, the technological conditions were kept constant. Mixed oxides are expected to exhibit superior electrochromic properties compared to the pure components, because of more intensive electron transfers between W and Mo states of different valence, or between one and the same metal state but with different structural disordering. The electrochromic characteristics were studied with the help of the cyclic-voltammetric technique. All films showed stabilized current–voltage (C–V) responses and good durability. The electrolyte used was LiClO₄+propylene carbonate. All films showed an electrochromic effect. Coloration as a result of Li intercalation was observed. For the as-deposited as well as the annealed mixed-oxide films, the current density was considerably larger than for pure metal oxide films. The electrochromic behavior was studied as a function of the annealing temperature.     

Nanostructured tungsten oxide with controlled properties: Synthesis and Raman characterization

Tungsten oxide thin films are interesting for their electrochromic and gas sensing properties. For technological applications, the control of morphology (effective surface, porosity) and structure (crystallinity, stoichiometry) at the nanoscale is of paramount interest to deliver distinctive properties.Nanostructured tungsten and tungsten oxide films have been synthesized by nanosecond pulsed laser deposition (PLD) starting from a W metallic target. Both inert and reactive buffer gases (He, Ar, dry air) have been exploited to induce cluster formation and/or oxidation and to vary the deposition energies of ablated species. A wide range of morphologies extending from compact and smooth, up to extremely porous and spongy-like structures have been obtained.The structure, the oxide phase and the degree of crystallinity of the films have been investigated by Raman spectroscopy. Films deposited in the presence of inert buffer gases reveal a spontaneous ex-situ oxidation, when exposed to ambient atmosphere, which is strongly related to the nanostructure. Instead, deposition in a varying pressure of dry air permits to grow tungsten oxide films and to tune their structure from amorphous to nano- and microcrystalline with different coexisting oxide phases.     

Amorphous WO3-x thin films with color characteristics tuned by the oxygen vacancies created during reactive DC sputtering

Tungsten oxides are interesting for a variety of applications due to their versatile optoelectronic charac-teristics,which can be tuned changing the composition and/or the crystalline structure.Coloration due to sub-bandgap absorption is often achieved by ion intercalation or doping in WO3:M films(with M=H+,Li+,Na+,etc.introducing extra electrons),but a more direct way is creating charged oxygen vacancies(Vo+and/or Vo2+)in sub-stoichiometric WO3-x forms.Here,amorphous WO3-x thin films are obtained by reactive DC sputtering of a pure W target,on unheated glass substrates,changing the oxygen to argon pressures ratio.The control of intrinsic defects(oxygen vacancies and tungsten valence states)by the oxy-gen partial pressure allows tuning the morphology,sub-bandgap absorption and carrier density in these WO3-x films,as it is proven by Raman spectroscopy,atomic force microscopy,optical spectrophotometry and Hall effect measurements.     

Insertion of H, Li, Na and K into thin films prepared from silicotungstic acid—a photoelectron spectroscopy study

Electrochemical insertion by a set of different ions (H⁺, Li⁺, Na⁺ and K⁺) into a tungsten oxide thin film was studied by photoelectron spectroscopy. The tungsten oxide thin film incorporating Si atoms was produced from a silicotungstic acid (SiWA) solution. The insertion compounds were measured by core level photoelectron spectroscopy (W 4f) and the contributions from ions of different oxidation states could be monitored simultaneously. SiWA films having a W⁶⁺/W_tot ratio of 0.7 could be prepared for all cations investigated. At this ratio the W 4f core level electronic structure for H⁺ inserted SiWA films was found to be very similar to that of H⁺ inserted into crystalline monoclinic WO₃ in that both films show the presence of W⁴⁺, W⁵⁺ and W⁶⁺. The measurements on Li⁺ inserted SiWA films indicate an electronic structure very similar to that of the smaller (H⁺) ion. The K⁺ inserted film displays a similar behaviour although the existence of W⁴⁺ was difficult to ascertain. Interestingly, a different behaviour was observed for the Na⁺ inserted compound. In this case, the binding energy shift of the W 4f peak upon reduction is clearly different from that obtained for the other insertion materials.     

Synthesis of one-dimensional potassium tungsten bronze with excellent near-infrared absorption property

Potassium tungsten oxide nanofibers were successfully synthesized via a facile hydrothermal reaction route in the presence of sulfate. After reduction under a reductive atmosphere of H(2)(5 vol %)/N(2), the potassium tungsten oxide transformed to potassium tungsten bronze. Because of the lack of free electrons, the potassium tungsten oxide (K(x)WO(3+x/2)) showed no NIR shielding performance; however, the potassium tungsten bronze (K(x)WO(3)) showed promising optical characteristics such as high transmittance for visible light, as well as high shielding performance for near-infrared lights, indicating its potential application as a solar filter. Meanwhile, the potassium tungsten bronze (K(x)WO(3)) showed strong absorption of near-infrared light and instantaneous conversion of photoenergy to heat.     

Dopant-dependent reflectivity and refractive index of microcrystalline HxWO3 and LixWO3 bronze thin films

Reflectivity spectra of HxWO3 and LiWO3 thin films were measured over the photon energy range from 0.4 to 4.2 eV. It was found that microcrystalline tungsten bronzes have reflectances of 8%-30% over the dopant concentration range x (0 < or = x < or = 0.25). Values for the real part of refractive index n were also determined from the refined reflectivity data. The optical data are interpreted by use of a modified Drude-Zener model together with a single-oscillator model to differentiate between bound and free electronic states. The values of high-frequency dielectric constant epsilon(hf) of MxWO3 (M = H+, Li+) bronzes were determined from the refractive-index data for estimation of the effective electronic masses involved in optical and polaronic transitions. A single-oscillator model showed that oscillator energy Ea and dispersion energy Ed increased and decreased, respectively, with increasing x values, opposite what occurs in crystalline tungsten bronzes. These findings support the fact that Bloch electrons are almost absent; instead, the polaronic species (W5+ and W4+) are assumed to control the reflectivity modifications (or variations in the refractive index) that are associated with the microcrystalline tungsten bronzes.