Mathematical model of thin-film electrode polarization

A polarization equation is derived for a thin-film electrode based on a silicon nanocomposite. The shallow thickness of the active layer (several micrometers) allows making some simplifying assumptions when deriving this equation and makes it possible to consider the case of weak polarization. For the polarization equation, a boundary problem is formulated, solutions are obtained, and system parameters for galvanostatic discharge are evaluated. It is shown that the parameters of the solutions meet the test conditions for experimental thin-film Si–O–Al samples and the condition of weak polarization.     

Megahertz operation of flexible low-voltage organic thin-film transistors

Bottom-gate, top-contact (inverted staggered) organic thin-film transistors with a channel length of 1 μm have been fabricated on flexible plastic substrates using the vacuum-deposited small-molecule semiconductor 2,9-didecyl-dinaphtho[2,3-b:2′,3′-f]thieno[3,2-b]thiophene (C₁₀-DNTT). The transistors have an effective field-effect mobility of 1.2 cm²/V s, an on/off ratio of 10⁷, a width-normalized transconductance of 1.2 S/m (with a standard deviation of 6%), and a signal propagation delay (measured in 11-stage ring oscillators) of 420 ns per stage at a supply voltage of 3 V. To our knowledge, this is the first time that megahertz operation has been achieved in flexible organic transistors at supply voltages of less than 10 V.     

Rigid and flexible thin-film multielectrode arrays for transmuralcardiac recording

Thin-film transmural cardiac multielectric arrays were fabricated using integrated-circuit processing techniques. Several substantial improvements were achieved over conventional handmade arrays such as a smaller cross-sectional area, a larger number of recording sites per needle, more accurately controlled size and spacing of the recording sites, smaller bipolar spacings, and higher throughout yield. These advantages allow for a higher density of closely spaced bipolar electrodes capable of monitoring complex voltage and gradient fields present during ventricular fibrillation and defibrillation. Both rigid and flexible arrays were fabricated and used in the acquisition of transmural electrical signals. The rigid multielectrode arrays were made of gold electrodes on a molybdenum substate, and the flexible arrays of silver and gold electrodes on a polyimide substrate. In vitro and in vivo testing of the thin-film transmural cardiac multielectrode arrays indicates that there are no adhesion or delamination problems observed during acute studies, no implantation difficulties, and that unipolar and bipolar recordings during normal sinus rhythm and injury potentials in unipolar recordings are similar to those obtained using the handmade electrodes.     

Analysis of fiber Brillouin ring laser composed ofsingle-polarization single-mode fiber

A fiber Brillouin ring laser made of SPSM fiber is analyzed. The eigenstate of polarization (ESOP) is strictly considered both for the pump and the Stokes light. It is clarified that the laser intensity fluctuation caused by the interaction between two kinds of ESOP is highly suppressed in this structure. The numerical computations using the typical values show that the fluctuation within 7.5% can be realized for the output Stokes light. While this ring-resonator does not offer high-grade performance when applied to the passive resonator fiber optic gyro, it could realize the high-grade performance when applied to the Brillouin fiber optic gyro     

Low-temperature materials and thin-film transistors for electronics on flexible substrates

The deposition processes and electronic properties of thin-film semiconductors and insulators based on silicon in relation to the fabrication of electronic devices on flexible plastic substrates are considered. The films of amorphous hydrogenated silicon (a-Si:H), nanocrystalline silicon (nc-Si), and amorphous silicon nitride (a-SiN_x), and also thin-film transistors are fabricated at comparatively low temperatures (120°C, 75°C) using existing commercial plasma-chemical equipment. The parameters of thin-film transistors based on a-Si:H and fabricated at the aforementioned relatively low temperatures are compatible with those of high-temperature analogues.     

Dye-doped submicron fiber waveguides composed of hole- and electron-transport materials

Dye-doped, submicron fiber waveguides composed of hole- and electron-transport materials, with a mean diameter of 480–660 nm were fabricated and their waveguiding properties studied. Dye emitted photoluminescence was guided in the fibers and the loss coefficient was calculated to be 1.2 × 10⁻³–3.9 × 10⁻³ μm⁻¹ at a wavelength of 540 nm, which is lower than previously reported for optically active polymer submicron fibers. Finally, a feasible method to couple the fibers with counter electrodes is presented using phase segregation of an insulating polymer. These submicron fiber waveguides, composed of optically and electrically active materials, can be used to produce OLED-waveguides, which are applicable in the fields of textile optoelectronics, lab-on-a-chip, and optogenetics.     

多芯光纤构成的温度与折射率同时测量的光纤传感器

本文设计了一种“单模光纤－多模光纤－多芯光纤－多模光纤－单模光纤”的全光 纤 Mach-Zehnder干涉仪结构。在该结构中多模光纤充当耦合器,不同模式的光在多芯光纤中 传输时将 产生光程差,形成Mach-Zehnder干涉。当环境温度和折射率变化时,通过分析干涉仪透射 光谱中不 同谐振峰的漂移量,实现折射率与温度的测量。实验结果表明,传感器低温灵敏度最高达到 46.0 pm/℃, 高温灵敏度最高达到109.0 pm/℃,折射率灵敏度最高达到54.3 nm/RIU(RIU为折射率单位)。另外, 通过同时监测传感器透射谱的两个谐振峰值波长随环境温度和折射率的漂移情况,实现了环 境温度 与折射率的同时测量,不存在交叉敏感。该传感器结构简单、制作容易、重复性好、响应稳 定、具 有多路复用功能,在传感领域有广泛的应用前景。     

Single mode grating coupling between thin-film and fiber optical waveguides

Optical directional coupling by means of a periodic perturbation is described between a clad, single mode, cylindrical fiber, and a thin-film planar waveguide. Codirectional coupling was achieved to a clad fiber, with 0.4 percent efficiency; allowing for the geometric mismatch, this is effectively 30 percent coupling. The fiber guided mode is accessed by reducing the fiber diameter by heating and pulling. Mode phase matching is achieved with a periodic grating sputter etched into the film. Unwanted grating induced interactions are minimized by restricting the guide parameters or by modifying the coupling mechanism. A perturbation analysis is used to calculate coupling coefficients and the design procedure for an optimum structure is explained. Measurements on grating couplers are described and the film/fiber codirectional coupling is shown to be effected by the grating.     

柔软光纤传像束的传像特性

研究了柔软光纤传像束的传像特性.界面交扰是柔软光纤传像束最重要的传像特性之一.迄今为止,有关这些方面的研究尚未完善.描述了一种采用光学视频系统定量测量柔软光纤传像束交扰率的新技术,并通过对柔软光纤传像束的静态MTF的测量和目视法观察,分析对比了交扰率对传像束传像特性的影响,比较了多种传像束样品的测量结果.     

Bias-stress stability of low-voltage p-channel and n-channel organic thin-film transistors on flexible plastic substrates

The bias-stress stability of low-voltage organic p-channel and n-channel thin-film transistors (TFTs) based on five promising organic semiconductors and fabricated on flexible polyethylene naphthalate (PEN) substrates has been investigated. In particular, it has been studied to which extent the bias-stress-induced decay of the on-state drain current of the TFTs is affected by the choice of the semiconductor and by the gate-source and drain-source voltages applied during bias stress. It has been found that for at least some of the organic p-channel TFTs investigated in this study, the bias-stress stability is comparable to that of a-Si:H and metal-oxide TFTs, despite the fact that the organic TFTs were fabricated at significantly lower process temperatures, which is important in view of the fabrication of these devices on plastic substrates.     

Low temperature fabrication of a ZnO nanoparticle thin-film transistor suitable for flexible electronics

A bottom-gate/top-drain/source contact ZnO nanoparticle thin-film transistor was fabricated using a low temperature annealing process (150 °C) suitable for flexible electronics. Additionally, a high-k resin filled with TiO₂ nanoparticles was used as gate dielectric. After fabrication, the transistors presented almost no hysteresis in the I–V curve, a threshold voltage (V_T) of 2.2 V, a field-effect mobility on the order of 0.1 cm²/V s and an I_ON/I_OFF ratio of about 10⁴. However, the transistor is sensitive to aging effects due to interactions with the ambient air, resulting in current level reduction caused by trapped oxygen at the nanoparticle surface, and an anti-clockwise hysteresis in the transfer curve. It was demonstrated, conjointly, the possible desorption of oxygen by voltage stress and UV light exposure.     

基于银纳米线的柔性透明电极的制备及性能研究

有机发光二极管(organic light emitting diodes, OLEDs)可以柔性制备,在未来的可穿戴应用上有广阔的发展前景,而柔性透明电极(flexible transparent electrode, FTE)的性能直接影响着柔性OLED的性能。本文基于银纳米线(AgNWs)和聚(3,4-乙烯二氧噻吩)∶聚苯乙烯磺酸(PEDOT∶PSS)制备了FTE,并采用甲醇浸渍、氩等离子处理、紫外辐射3种不同的方式对该电极进行处理,优化FTE的光电性能。研究发现：甲醇浸渍,可减少AgNWs上聚合物的包覆;等离子体处理和紫外辐射,可对AgNWs进行焊接;而两种方式的协同作用则可以对FTE的光电性能进一步优化。实验获得最优FTE的方阻为14.18Ω/sq,在550 nm处的透过率可达到84%以上。经过500次弯曲测试后,FTE的方阻变化率低于15%。本文的工作对FTE的制备及优化提供了可行性方案。     

On the quality of contacts in a-Si:H staggered electrode thin-film transistors

Amorphous silicon thin-film field-effect transistors have been made with a staggered electrode structure. In this structure we distinguish two separate contributions to the total contact resistance, namely, the Al/a-Si:H barrier itself and the bulk resistance of the underlying a-Si:H layer. Concerning the first contribution it was found that a P-implantation forming n⁺regions followed by post-metallization annealing (PMA) at a moderate temperature of 200°C is very efficient in reducing the resistance of the Al contacts to negligibly small values. The second contribution, i.e., the bulk resistance, implies a variable series resistance in field-effect (FE) measurements. Thin-film transistors (TFT's) with different gate lengths were used for the first time to determine this residual series resistance Rres.     

Bias of a resonator fiber optic gyro composed of apolarization-maintaining fiber ring resonator with the photoinducedbirefringent grating

A theoretical study of the polarization-fluctuation induced bias of an resonator fiber optic gyro (R-FOG), which employs a polarization-maintaining fiber ring resonator with a photoinduced birefringent grating, is presented. The polarization conversion due to the photoinduced birefringent grating can stabilize the resonator output, which result in the reduction of the bias in the R-FOG output. The influences of the parameters, such as the fluctuation of the input polarization, the resonator finesse, and the photoinduced index change of the dielectric tensor, on the bias in the gyro-output have been investigated. Our results show that with the help of a photoinduced birefringent grating the bias in the gyro-output can be limited around 10^-7 rad/s (0.02 deg/hr), a typical specification for the aircraft-navigation     

介电弹性体驱动器柔性电极技术发展动态

对介电弹性体柔性电极相关研究进行了总结和分析。柔性电极是介电弹性体发电或驱动材料的重要组成部分,其性能直接影响介电弹性体发电机的发电效率以及驱动器的驱动性能。目前,对柔性电极的研究处于起步阶段。本文基于介电弹性体材料的不同用途,分析了碳基电极、碳纳米管电极等几种典型的柔性电极材料的性能、制备工艺及方法。并针对其应用条件的不同,分析了电极材料的应用领域。经过研究分析发现,柔性电极材料需要具备柔性大、导电性高这两点特性,但是目前柔性电极在柔性与导电性上不能兼具,存在贴合度不足、导电性差等问题,需要对柔性电极的材料以及制备工艺进行更加深入的研究。     

多壁碳纳米管/棉织物复合柔性电极的制备

近年来柔性超级电容器在柔性电子设备领域起到越来越重要的作用,其中电活性材料与织物的结合是制备柔性电极的关键。本文针对棉织物进行多壁碳纳米管的高密度堆积性研究,并进行循环伏安曲线测试、充放电测试和交流阻抗测试。研究表明,该复合材料具备电极的应用性质,以及良好的循环稳定性和弯曲性,为进一步制备高电容量的柔性超级电容器打下了基础。     

An analysis of deep depletion thin-film MOS transistors

Consideration is given to the problems associated with the use of an insulated gate to obtain depletion in the channel of a field-effect transistor. It is shown that if an inversion layer forms at the insulator semiconductor interface before the channel is completely depleted complete pinch-off of drain current by the gate will not be observed. It is further shown that channel pinch-off at the drain will always occur and, hence, that drain current saturation will always be observed. A quantitative analysis based on the proposed model is performed and theoretical expressions for the device behavior are derived and plotted. The analysis of the device is divided into two ranges, a high-frequency range and a low-frequency range, where the dividing frequency is the frequency response of the surface inversion layer. This dividing frequency is generally orders of magnitude lower than the upper operating frequency limit of the transistor itself. Finally, the theoretical results are compared with experiment and shown to be in good agreement.     

Integration of a graphene ink as gate electrode for printed organic complementary thin-film transistors

We demonstrate a new electrode gate based on graphene ink for complementary printed organic metal oxide semiconductor (CMOS) technology on flexible plastic substrates. The goal is to replace the standard silver electrode gate. Devices made with graphene were enhanced and showed a high field-effect mobility of 3 cm² V⁻¹ s⁻¹ for P-type and 0.9 cm² V⁻¹ s⁻¹ for the N-type semiconductors. The improvement is attributed to the increase of the electrical capacitance of the organic dielectric (CYTOP) due to the graphene layer. A seven-stage ring oscillator was made with high oscillation frequencies of 2.1 kHz at 40 V corresponding to a delay/gate value of 34 μs. These performances are promising for use of low cost printed electronic applications.     

染料敏化太阳能电池TiO2薄膜电极的染料吸附性能研究

采用手工刮涂法制备了染料敏化太阳能电池( DSSC)的TiO2薄膜电极,用解吸的方法和正交试验研究了DSSC电池TiO2薄膜电极的染料吸附性能,并结合统计分析方法对染料吸附试验数据进行了分析处理.研究结果表明TiO2薄膜电极具有最优染料吸附性能的烧结条件为:以2℃/min的速率升温至450℃,保温50 min后随炉冷却...     

Fabrication of the flexible pentacene thin-film transistors on 304 and 430 stainless steel (SS) substrate

Flexible organic thin-film transistors (OTFT) were fabricated on 304 and 430 stainless steel (SS) substrate with aluminum oxide as a gate insulator and pentacene as an organic semiconductor. Chemical mechanical polishing (CMP) process was used to study the effect of the SS roughens on the dielectric properties of the gate insulator and OTFT characteristics. The surface roughness was decreased from 33.8 nm for 304 SS and 19.5 nm for 430 SS down to ～2.5 nm. The leakage current of the metal–insulator–metal (MIM) structure (Au/Al₂O₃/SS) was reduced with polishing. Mobility and on/off ratio of pentacene TFT with bare SS showed a wide range of values between 0.005 and 0.36 cm²/Vs and between 10³ and 10⁵ depending on the location in the substrate. Pentacene TFTs on polished SS showed an improved performance with a mobility of 0.24–0.42 cm²/Vs regardless of the location in the substrate and on/off ratio of ～10⁵. With self assembled monolayer formation of octadecyltrichlorosilane (OTS) on insulator surface, mobility and on/off ratio of pentacene TFT on polished SS was improved up to 0.85cm²/Vs and ～10⁶. I–V characteristics of pentacene TFT with OTS treated Al₂O₃/304 SS was also obtained in the bent state with a bending diameter (D) of 24, 45 or 70 mm and it was confirmed that the device performed well both in the linear regime and the saturation regime.