Thin film stress measurement by instrumented optical fibre displacement sensor

Residual stress can adversely affect the mechanical, electronic, optical and magnetic properties of thin films. This work describes a simple stress measurement instrument based on the bending beam method together with a sensitive non-contact fibre optical displacement sensor. The fibre optical displacement sensor is interfaced to a computer and a Labview programme enables film stress to be determined from changes in the radius of curvature of the film-substrate system. The stress measurement instrument was tested for two different kinds of thin film, hard amorphous carbon nitride (CN) and soft copper (Cu) films on silicon substrates deposited by RF magnetron sputtering. Residual stress developed in 500 nm thick CN thin films deposited at substrate temperatures in the range 50-550 °C was examined and it was found that stress in CN films decreased from 0.83 to 0.44 GPa compressive with increase of substrate temperature. Residual stress was found to be tensile (121 MPa) for Cu films of thickness 1500 nm deposited at room temperature.     

Zn、Cu共掺杂TiO_2∶SiO_2薄膜材料的光学性能研究

用溶胶-凝胶法制得Zn、Cu共掺杂的TiO_2∶SiO_2凝胶,旋转法于玻璃基底涂膜,制得Zn、Cu共掺杂的TiO_2∶SiO_2薄膜,探讨了煅烧温度、煅烧时间及掺杂比例对其结构、形貌和性能的影响。采用XRD、FESEM、FTIR等测试技术对薄膜进行表征,并考察了其对甲基橙的光催化降解性能。XRD测试结果显示:薄膜样品的晶型为锐钛矿型,结晶良好。SEM谱图显示:薄膜微粒粒径小,分布均匀,表面平整、致密且无明显裂痕;紫外-可见光谱(UV-Vis)表明:Zn、Cu共掺杂的TiO_2∶SiO_2薄膜在紫外区和可见光区的吸光度明显增加,提高了对光的利用率;光催化性能测试表明:与纯相TiO_2对比,Zn、Cu共掺杂的TiO_2∶SiO_2薄膜对甲基橙的光催化降解率有较大提高,在600℃下焙烧2h的掺杂的量比为n(Ti)∶n(Si)∶n(Zn)∶n(Cu)=3∶2∶1.5∶4的薄膜样品光催化降解率最高。     

OLED薄膜干燥剂的制备及其对OLED的影响

有机电致发光显示器对水和氧气非常敏感,渗入器件后会和有机功能层及电极材料反应而影响器件的寿命及稳定性。本文提出了一种液体可涂覆干燥剂的制备方法,采用了氯化物干燥剂和价格低廉的阳离子成膜剂结合合成一种具有很好成膜性、且吸水效果很强的涂覆干燥剂。封装240 h后,使用薄膜干燥剂的器件的亮度分别为平均值的103.5%、83.3%以及119.8%,效率为平均值的130.7%、65.6%以及126.0%。与传统干燥剂相比,该薄膜干燥剂的吸湿效果更佳,且可延缓OLED的老化。     

单端面长周期光栅透射模式测量技术

为了实现长周期光栅透射谱测量模式的远距离监测,设计了单端面镀反射膜的测量装置系统,对单端面镀银膜长周期光栅的传感原理做了分析,并从实验的角度分别对单端面镀银膜模式系统和直接透射模式系统的长周期光栅在不同折射率的环境介质中的响应进行了研究,比较了它们的异同。首先,采用2×2单模光纤耦合器分别连接光谱分析仪、光源、长周期光栅。然后,在包含长周期光栅的光纤的另一个端面制备反射银膜。最后,通过测量一系列不同折射率的环境介质,比较了直接透射模式与单端面镀银膜模式下的长周期光栅的响应光谱。实验结果表明:采用波长解调表达时,对于同一种环境介质,两种模式下长周期光栅的响应光谱的谐振波长基本相同;采用功率/峰值解调表达时,随着甘油浓度从水变为80%的甘油溶液,直接透射模式下的光损耗从-6.05 d B变为-9.22 d B,单端面镀银膜模式下的光损耗从-8.03 d B变为-11.33d B。与直接透射模式相比,单端面镀银膜的长周期光栅光谱中的相对光损耗明显增加,谐振峰更尖锐,更有利于谐振波长和谐振峰光损耗值的识别。本研究设计的单端面镀银膜的长周期光栅测量系统不仅保留了长周期光栅透射谱的感应模式,而且使长周期光栅在对环境介质的测量中操作更加灵活方便,尤其是在远距离、恶劣环境或深层液体的折射率测量中具有独特的优势。     

Electrochemical behaviour of sputtered c-V2O5 and LiCoO2 thin films for solid state lithium microbatteries

Here are reported for the first time electrochemical data on all-solid-state lithium microbatteries using crystalline sputtered V₂O₅ thin films as cathode materials and LiPON as solid electrolyte. The stable specific capacity of 30 µAh/cm² found with a 2.4 µm thick film competes very well with the best values obtained for solid state microbatteries using amorphous films. With the challenge of decreasing the temperature of heat treatment for sputtered LiCoO₂ thin films, we show that a temperature of 500 °C combined with an optimized bias sputtering (-50 V) allows to get highly crystalline deposits, to minimize the presence of Co₃O₄ and to suppress any trace of the cubic phase. At the same time the theoretical specific capacity is reached in the 4.2 V-3 V range and a good cycling behaviour is achieved with a high capacity of 50 µAh/cm²/µm after 140 cycles at 10 µA.cm².     

Thiolated cyclodextrin self-assembled monolayer-like characterized with secondary ion mass spectrometry

In the work the focus is on the preparation of self-assembled monolayer-like films consisting of thiolated cyclodextrin on gold substrate and a characterization by using secondary ion mass spectrometry. The short (1 min) and long (1 h) time preparations of self-assembled monolayer-like films, resulting in submonolayer and monolayer regimes, are investigated, respectively. The observed species of thiolated cyclodextrin (M as molecular ion) self-assembled monolayer-like films are assigned to three groups: Au_xH_yS_z clusters, fragments with origin in cyclodextrin molecule associated with Au, and molecular ions. The group of Au_xH_yS_z (x = 2-17, y = 0-2, z = 1-5) clusters have higher intensities than other species in the positive and even more in negative mass spectra. Interestingly, the dependence between the number of Au and S atoms shows that with the increasing size of Au_xH_yS_z clusters up to 11 Au atoms, the number of associated S atoms is also increasing and then decreasing. Molecular species as (M−S+H)Na⁺, (M+H)Na⁺, AuMNa⁺, (M₂−S)Na⁺, and M₂Na⁺ are determined, and also in cationized forms with K⁺. The intensities of thiolated cyclodextrin fragments at the long time preparation are approximately 10 times higher than the intensities of the same fragments observed at the short time. The largest observed ions in thiolated cyclodextrin self-assembled monolayer-like films are AuM₂ and Au₂M. The thiolated cyclodextrin molecular ions are compared with hexadecanethiol molecular ions in the form of Au_xM_w where the values of x and w are smaller for thiolated cyclodextrin than for hexadecanethiol. This result is supported with larger, more compact, and more stabile thiolated cyclodextrin molecule.     

Micromegas prototypes with thermo-bond film separators

In this paper we report the results of Micromegas prototypes constructed by attaching micromesh to an anode using thermo-bond films. The excellent metal attaching ability and good dielectical property of this kind of film make it a promising material to be used as avalanche gap spacers. Several prototypes are successfully made. The electron transmission properties are first studied and then the gas gain is measured in argon-isobutane mixtures. The maximum gain of more than 104 is easily obtained. The energy resolutions for 55Fe 5.9 keV Kα ray can be better than 20% over one magnitude in gain for different operational gas mixtures and the best energy resolution of 13.7% (FWHM) can be achieved with the gas mixture of 94% argon concentration. The preliminary test results of the prototypes with sensitive area of 45 mm×45 mm without internal support show good uniformity across the sensitive area.     

晶粒尺寸对气相沉积薄膜磁取向生长的影响研究

为了研究强磁场下薄膜取向生长规律,采用真空蒸发气相沉积法分别制备了不同磁场方向生长的Zn和Bi薄膜.XRD结果发现磁化率差异较小的Zn薄膜在4T时产生了明显的取向生长,而磁化率差异较大的Bi薄膜在5T磁场强度还没有发生取向生长.SEM结果显示Zn薄膜和Bi薄膜晶粒尺寸上有明显的差别,利用Zn薄膜在4T磁场下的取向建立晶粒尺寸和取向生长的对应关系,提出薄膜发生取向时晶粒的磁化能须大于热能kT的420倍.薄膜是否发生取向生长取决于三个因素:薄膜单个晶粒的大小V,材料不同晶向的磁化率差异Δ关键词： 强磁场 磁取向 薄膜生长 材料电磁加工     

Valence control of cobalt oxide thin films by annealing atmosphere

The cobalt oxide (CoO and Co₃O₄) thin films were successfully prepared using a spin-coating technique by a chemical solution method with CH₃OCH₂CH₂OH and Co(NO₃)₂·6H₂O as starting materials. The grayish cobalt oxide films had uniform crystalline grains with less than 50 nm in diameter. The phase structure is able to tailor by controlling the annealing atmosphere and temperature, in which Co₃O₄ thin film was obtained by annealing in air at 300-600, and N₂ at 300, and transferred to CoO thin film by raising annealing temperature in N₂. The fitted X-ray photoelectron spectroscopy (XPS) spectra of the Co2p electrons are distinguishable from different valence states of cobalt oxide especially for their satellite structure. The valence control of cobalt oxide thin films by annealing atmosphere contributes to the tailored optical absorption property.     

Fabrication of durable hydrophobic surfaces through surface texturing

Low surface energy polymer thin-films can be applied to surfaces to increase hydrophobicity and reduce friction for a variety of applications. However, wear of these thin films, resulting from repetitive rubbing against another surface, is of great concern. In this study, we show that highly hydrophobic surfaces with persistent abrasion resistance can be fabricated by depositing fluorinated carbon thin films on sandblasted glass surfaces. In our study, fluorinated carbon thin films were deposited on sandblasted and as-received smooth glass using deep reactive ion etching equipment by only activating the passivation step. The surfaces of the samples were then rubbed with FibrMet abrasive papers in a reciprocating motion using an automatic friction abrasion analyzer. During the rubbing, the static and kinetic friction forces were also measured. The surface wetting properties were then characterized using a video-based contact angle measuring system to determine the changes in water contact angle as a result of rubbing. Assessment of the wear properties of the thin films was based on the changes in the water contact angles of the coated surfaces after repetitive rubbing. It was found that, for sandblasted glass coated with fluorinated carbon film, the water contact angle remained constant throughout the entire rubbing process, contrary to the smooth glass coated with fluorinated carbon film which showed a drastic decrease in water contact angle with the increasing number of rubbing cycles. In addition, the static and kinetic friction coefficients of the sandblasted glass were also much lower than those of the smooth glass.