Structure and optical properties of C60 films on polymer substrates

The results of investigations of the structure and optical properties of films of fullerene C₆₀ are reported. The films were obtained by vacuum thermal evaporation on substrates from heat-resistant polymers (polyacrylonitrile and cyclized polyacrylonitrile in composition with polyimide). The structure of C₆₀ films was determined by X-ray diffractometry. In all diffraction patterns of fullerene films, their structure manifests itself through reflections from the (111), (220), and (311) planes. Cubic C₆₀ films were obtained by fullerene deposition at substrate temperatures as high as 200°C. Atomic force microscopy of the film surface revealed the existence of a laminated structure. The infrared (IR) transmission spectra are indicative of the presence and constancy of the position of characteristic bands of C₆₀ (527, 576, 1183, and 1428 cm^?1) for all fullerene films. The investigation of photoluminescence of fullerene films revealed bands whose energy position both exceeded typical values for molecular C₆₀ or fell below these values. This circumstance is caused by the interaction between the electron π systems of C₆₀ and the polymer substrate at the heterointerface, as well as by the photopolymerization reaction of fullerene under the effect of high-energy laser radiation and by the emergence of trap centers in the films.     

Amorphous Carbon Nanotubes with Tunable Properties via Template Wetting

Amorphous carbon nanotubes have been prepared by casting thin films of polyacrylonitrile (PAN) and polystyrene‐block‐polyacrylonitrile (PS‐b‐PAN) within a porous anodic aluminum oxide (AAO) membrane followed by pyrolysis. Raman and wide‐ angle X‐ray diffraction (WAXD) measurements indicate that the carbon nanotubes are of low crystallinity. The thickness of the carbon nanotube walls is controlled by either changing the concentration of the precursor solution or by using multiple casting and pyrolysis steps. When diblock copolymers of PS‐b‐PAN are used, it is found that nanopores are created within the nanotube walls after pyrolysis. The carbon nanotubes can be used to create carbon coated nanorods of polystyrene‐block‐polybutadiene (PS‐b‐PBD).     

Composites of Polyacrylonitrile and Multiwalled Carbon Nanotubes Prepared by Gelation/Crystallization from Solution

Composite films of polyacrylonitrile (PAN) and multiwalled carbon nanotubes (MWNTs) have been prepared by gelation/crystallization from solution. The contents of MWNTs were 5–10 wt.‐%, measured against PAN. The electrical and mechanical properties have been studied in comparison with those of the homopolymer PAN films prepared from the same method. Furthermore, stabilization and the carbonization have been carried out by using the drawn PAN–MWNTs as a new precursor to prepare carbon films with a cross‐sectional area much larger than that of a commercial carbon fiber (> 3000 times). The MWNTs within the PAN matrix promote the formation of a condensed aromatic ladder structure during the stabilization process and play an important role in preparing PAN‐based carbon material with high carbon quality and high mechanical properties. When the stabilized composites with 10 wt.‐% MWNTs are carbonized at 1000 °C, the Young's modulus reaches 37.5 GPa, and the electrical conductivity reaches 10² S cm^–1. The carbonized PAN homopolymer does not form an adequately robust bulk film for the mechanical properties to be measured.     

Tailoring Noncovalent Interactions to Activate Persistent Room-Temperature Phosphorescence from Doped Polyacrylonitrile Films

Organic phosphors exhibiting room-temperature phosphorescence (RTP) in amorphous phase are good candidates for optoelectronic and biomedical applications. In this proof-of-concept work, a rational strategy to activate wide-color ranged and persistent RTP from amorphous films by embedding electron-rich organic phosphor into electron-deficient matrix polyacrylonitrile (PAN) is presented. Through tailoring noncovalent interactions between the electron-deficient PAN matrix and electron-rich organic phosphors, an ultralong lifetime of 968.1 ms is obtained for doped film TBB-6OMe@PAN. Control experiments conducted on the polymers polymethyl methacrylate (PMMA) and polystyrene (PS) without electron-withdrawing groups, and organic phosphors containing electron-withdrawing groups indicate that the persistent RTP of doped films may be triggered by strong electrostatic interactions between electron-deficient PAN and electron-rich organic phosphor. Further theoretical calculations including electrostatic potential distributions, binding energies, and energy decomposing analysis demonstrate that both electrostatic and dispersion interactions between electron-deficient PAN and electron-rich organic phosphor are responsible for the activation of persistent RTP of doped films. In addition, the doped film TBB-6OMe@PAN still maintains brightness even after soaking in water for 12 weeks. This excellent water resistance not only is favorable for future applications but also demonstrates an advantage of electrostatic and dispersion interactions over hydrogen bonding interactions.     

Thermoelectric Potential of Polymer-Scaffolded Ionic Liquid Membranes

Organic thin films have been viewed as potential thermoelectric (TE) materials, given their ease of fabrication, flexibility, cost effectiveness, and low thermal conductivity. However, their intrinsically low electrical conductivity is a main drawback which results in a relatively lower TE figure of merit for polymer-based TE materials than for inorganic materials. In this paper, a technique to enhance the ion transport properties of polymers through the introduction of ionic liquids is presented. The polymer is in the form of a nanofiber scaffold produced using the electrospinning technique. These fibers were then soaked in different ionic liquids based on substituted imidazolium such as 1-ethyl-3-methylimidazolium chloride or 1-butyl-3-methylimidazolium bromide. This method was applied to electrospun polyacrylonitrile and a mixture of polyvinyl alcohol and chitosan polymers. The ion transport properties of the membranes have been observed to increase with increasing concentration of ionic liquid, with maximum electrical conductivity of 1.20 × 10^?1 S/cm measured at room temperature. Interestingly, the maximum electrical conductivity value surpassed the value of pure ionic liquids. These results indicate that it is possible to significantly improve the electrical conductivity of a polymer membrane through a simple and cost-effective method. This may in turn boost the TE figures of merit of polymer materials, which are well known to be considerably lower than those of inorganic materials. Results in terms of the Seebeck coefficient of the membranes are also presented in this paper to provide an overall representation of the TE potential of the polymer-scaffolded ionic liquid membranes.     

共蒸发三步法制备CIGS薄膜的性质

采用PID温度控制器控制共蒸发设备中蒸发源及衬底加热的温度,以三步法工艺制备CIGS(Cu(In,Ga)Se2)薄膜,通过恒功率加热衬底测试温度的变化,可实现在线组分监测,得到CIGS薄膜的组成重现性很好.CIGS薄膜的表面光洁,粗糙度多数小于10nm.但是组成相同的CIGS薄膜,其结晶择优取向可能不同,主要有(112)和(220)/(204)两种;其结晶形貌也有很大的不同,晶粒粗大且成柱状的薄膜电池效率高,虽然从Cu/(In Ga)＜1的组成可以认为CIGS薄膜为贫Cu结构,但Hall测试多数CIGS薄膜呈p型,少数呈n型.     

基片温度对电子束蒸发的ZnS薄膜性能的影响

采用电子束蒸发在不同基片温度下沉积ZnS薄膜,研究了基片温度对薄膜性能的影响.结果表明:不同基片温度下沉积的ZnS薄膜均呈多晶状态,为体心立方(闪锌矿)结构的β-znS,并具有明显的(111)面择优取向,导电类型为n型.随着成膜时基片温度的提高,薄膜结晶度越来越好,透过率增大,载流子浓度增大,而电阻率减小.     

钽酸锂薄膜溶胶凝胶制备工艺研究

用溶胶–凝胶法在不同衬底上制备了新的钽酸锂薄膜;研究了环氧树脂掺杂、甩胶转速、衬底效应、热处理温度和气氛等薄膜制备工艺条件对薄膜晶向、表面形貌和介电特性的影响。结果表明:当溶胶浓度为0.1mol/L,转速为3000r/min,能制备出均匀、平整、无裂纹的薄膜;控制掺杂环氧树脂在5%左右(质量分数),能提高薄膜与衬底的黏附性;薄膜在氧气气氛下结晶退火,比在氮气气氛下具有更小的介质损耗;n型Si、p型Si和SiO2衬底上钽酸锂薄膜在[012]晶向上具有择优取向性,而Pt衬底上薄膜在[110]、[116]晶向上具有择优取向性。     

Ti-O化合物制备TiO2薄膜热处理及透射率研究

采用离子束辅助蒸发,以TiO2,Ti3O5,Ti2O3为膜料,制备了具有良好光学透射性的TiO2薄膜.结果分析表明,所制备出的TiO2薄膜均为非晶态结构,退火后薄膜发生晶化均具有明显的(101)择优取向;晶化的程度和退火温度的高低有关;退火处理之后以TiO2,Ti3O5为膜料制备的薄膜透射率下降,而以Ti2O3为膜料的上升;膜料不同对氧的需求量不同:以TiO2,Ti3O5为膜料制备薄膜所需氧量,远小于以Ti2O3为膜料所需氧量,氧流量过多降低了薄膜的透射性能,且随氧流量的不同,薄膜的透射率曲线均发生偏移,膜料不同偏移度也不同.     

Metal direct nanoimprinting for photonics

In this paper metal direct nanoimprinting (embossing) for the production of metallic microparts is discussed, with a main focus on its suitability for the fabrication of metal-containing optical devices such as photonic crystals, plasmon waveguides or chiral structures. Silver and gold were chosen, since they have the lowest light absorption in the near infrared and visible range. They are also easily formable due to their good ductility, which can be further enhanced by processing at elevated temperature. The mold material, which may form part of the optical device, usually consisted of silicon, but other dielectric materials such as silicon oxide and silicon nitride were also successfully tested.Cylindrical and line-shaped holes with lateral dimensions down to 250 nm and aspect ratios of up to 5 were etched in silicon wafers. All the structures were successfully filled with silver and gold, and the filling of smaller dimensions is also deemed possible. This technique is therefore suitable for producing metal-containing optical devices working in the infrared, at least down to the standard telecom wavelength of 1.5 μm, which requires metallic dimensions of 200-300 nm.     

隔热结构中非晶硅的释H_2机理与工艺研究

对采用等离子增强化学气相淀积法(PECVD)制备的氢化非晶硅(a-Si:H)薄膜进行了退火释H2实验,并对三文治结构膜层生长工艺作了改进。红外透射光谱表明:提高退火温度及增加退火时间会造成Si-H键断裂释放H2影响器件结构完整;不断改进设计,最终采用精简有效热敏面积及将退火工艺提前以扩张释H2渠道的方案,获得600℃退火后仍保持完整三文治结构的优化设计流程。     

RF磁控溅射功率对ZnO:Al薄膜结构和性能的影响

采用RF磁控溅射技术以ZnO:Al2O3(2 wt%Al2O3)为靶材在石英玻璃衬底上制备多晶ZnO:Al(AZO)薄膜,通过XRD、AFM、AES以及Hall效应、透射光谱、折射率等手段研究了RF溅射功率(50～300 W)对薄膜的组织结构和电学,光学性能的影响.分析表明:所制备的AZO薄膜具有c轴择优取向,并且通过对不同功率下薄膜载流子浓度与迁移率的研究发现对于室温下沉积的AZO薄膜,晶粒间界中的O原子吸附是影响薄膜电学性能的主要因素.同时发现当功率为250 W时薄膜的电阻率降至最低(3.995×10-3 Ω·cm),可见光区平均透射率为91%.     

掺铂WO3-SiO2复合薄膜结构表征和气致变色性能研究

采用溶胶－凝胶法制备WO3－SiO2复合薄膜,对不同温度热处理的复合薄膜及单一组分薄膜的结构和气致变色性能进行了对比分析。XRD分析结果表明,复合薄膜的晶化温度提高、晶化程度降低,存在一定的晶格畸变;IR分析结果表明,在热处理过程中复合薄膜氧化钨分子间不易缩合,分子结构对称性低、变形多。性能测试结果表明,在复合薄膜中,WO3与SiO2之间的相界等结构缺陷为氢气提供扩散通道,使复合薄膜在热处理后气致变色性能优于单一组分薄膜。     

离子束溅射制备的氧化钽层的绝缘特性

介绍了一种具有高附着力和优良绝缘性能的Ta2O5介质膜，它由离子束溅射镀膜工艺制备而成。检测了在不同氧气流量下制备的氧化钽薄膜的绝缘性。结果表明：在其余条件相同的情况下，氧气流量越大所制备的薄膜绝缘程度越高。但当氧气流量达到一定的程度时，其绝缘程度不再有所变化。     

衬底温度对反应溅射TiN_x薄膜结构与电阻率的影响

采用反应磁控溅射方法,在不同Si(100)衬底温度下,制备出了TiNx薄膜。通过X射线衍射(XRD)、扫描电子显微镜(SEM)对TiNx薄膜的物相、微观结构进行了表征,采用电子能谱仪(EDS)测定了TiNx薄膜的成分,运用四探针测试仪测量了TiNx薄膜的电阻率,研究了衬底温度对溅射TiNx薄膜结构与电阻率的影响。研究结果表明:衬底温度从室温升高到600℃时,随着温度升高,TiNx薄膜的(111)晶面衍射峰逐渐增强,500℃后减弱;(200)晶面衍射峰在300℃时最强,之后减弱。随着衬底温度的升高,TiNx薄膜的晶粒逐渐增大,300℃达最大后减小。随着衬底温度升高,TiNx薄膜的N/Ti原子含量比降低,200℃时降到最低为0.99,随后升高,500℃时最高为1.34,随后再次降低。N/Ti原子含量比与薄膜电阻率呈明显反比变化。     

Permittivity and loss tangent of pyrolised polyacrylonitrile fibre

Microwave absorbers are used to reduce the power scattered in free-space determinations to a negligible level. In this letter the results of permittivity and loss-tangent measurements on absorbing materials of pyrolised polyacrylonitrile fibres are reported.     

晶向对SnO2:F透明导电玻璃特性的影响

本文利用超声喷雾法制备了SnO2:F透明导电薄膜,snCl4·5H2O与NH4F分别用作锡源与氟掺杂,玻璃衬底温度控制在360℃.X射线衍射仪、扫描电镜、紫外可见分光光度计与四探针仪分别用于表征样品的晶体结构、表面形貌、透光率与面电阻.研究结果表明:超声喷雾沉积的SnO2:F薄膜主要为四方晶系的多晶薄膜,并且随着沉积条件的改变,在(110)、(220)晶向出现不同程度的择优取向,其中在(200)晶向上择优取向生长的薄膜面电阻明显低于(110)晶向,最低可达到5 Ω/□,所有样品透光率都较高,在450～1000 nm范围内的平均透光率可达到80～90%.     

Al掺杂半导体Mg2Si薄膜的制备及电学性质

采用磁控溅射方法和热处理工艺在Si衬底上制备了不同Al质量分数的Mg2Si薄膜,研究了不同Al质量分数对Mg2Si薄膜结构及其电学性质的影响.通过X射线衍射仪(XRD)、扫描电子显微镜(SEM)和四探针测试仪对Al掺杂Mg2Si薄膜的晶体结构、表面形貌和电学性质进行表征和分析.结果表明:采用磁控溅射技术在Si衬底上成功制备了不同Al质量分数的Mg2Si薄膜,样品表面表现出良好的连续性,在Mg2Si (220)面具有择优生长性.随着质量分数的增加,结晶度先增加后降低,晶粒尺寸减小,且在Al质量分数为1.58％时结晶度最好.此外,样品电阻率也随着Al质量分数的增加逐渐降低,表明Al掺杂后的Mg2Si薄膜具有更好的导电性,这对采用Mg2Si薄膜研制半导体器件有着重要的意义.     

Optical Constants and Structure of ZnO Films by Radio Frequency Magnetron Sputtering

ZnO films are deposited on glass slides by radio frequency（RF） magnetron sputtering under different powers. The polycrystal structures and surface morphologies of the film are investigated. The optical transmission spectra for the ZnO films are measured within the range from 300 nm to 800 nm. The optical constants and thickness of the films are determined using a nonlinear programming method suggested by Birgin et al. The band gap of the film increases with reducing the nano-size of the film grains. The packing density of the films can be improved by reducing the RF power.     

Correlation of Gm degradation of submicrometer MOSFETswith refractive index and mechanical stress of encapsulation materials

Evaluations of five different plasma-deposited silicon nitride films for use as an encapsulation material for polysilicon-gate MOSFETs are discussed. The films were (1) a-SiN:H; (2) Applied Materials a-SiN:H process B; (3) Applied Materials a-SiN:H process D; (4) silicon oxynitride, a-SiON:H; and (5) fluorinated silicon nitride, a-SiNF:H. Submicrometer MOSFET devices that aged the least as measured by transconductance degradation were encapsulated with films having the lowest refractive index (a-SiON:H and a-SiNF:H). The results show that films with low refractive index and low absolute value of mechanical stress age the least. The results are interpreted in terms of the Meyer-Fair model where the lower refractive index films are more porous to H leaving the device than the higher refractive index films