Annealing temperature effect on structural,optical, morphological and electrical properties of CdS/Si(100) nanostructures

CdS nanostructures have grown on p-type silicon (Si) (100) substrates using sol–gel method. The crystalline quality, surface morphology, optical and electrical properties of the deposited CdS nanostructures have been characterized and analyzed using atomic force microscopy, scanning electron microscopy, X-ray diffraction, thermogravimetric analysis, differential thermal analysis, UV–vis spectroscopy and electrical characterization, respectively. The effect of annealing temperature in the range 200–600 °C on the structural, morphological, optical and electrical properties has been elaborated. The XRD analysis shows that the crystalline quality can be improved by increasing the temperature to 400 °C, but further increase to 600 °C leads to degradation of crystalline quality. The bulk modulus is calculated and showed good agreement with experimental and theoretical results. The optical properties of absorption, reflection, energy band gap and extinction coefficient are obtained by UV–vis spectroscopy. The calculated refractive index and optical dielectric constant have shown good agreement with other results. The electrical and thermal properties are studied for antireflection coating applications.     

Tuning of electrical and optical properties of organic LEDs using combinatorial device fabrication

The capabilities of combinatorial methods are presented in order to get a detailed understanding of the electrical and optical properties of organic light‐emitting devices (OLEDs), to optimize their performance, and to provide reliable data for device modeling. We show results on multilayer OLEDs ranging from the conventional copper‐phthalocyanine (CuPc)/N,N′di‐(naphtalene‐1‐yl)‐N,N′‐diphenyl‐benzidine (NPB) and tris‐(8‐hydroxy‐quinolinato)aluminum (Alq) tri‐layer device to double‐doped deep‐red‐emitting OLEDs.     

The electrical and optical properties of AZO thin film under different post-annealing temperatures

In this study, the Aluminum element doped zinc oxide (Al:ZnO) thin film was deposited on the Corning glass substrate by RF magnetron sputtering technology and annealing treatment. After sputtering, all thin films are then annealed on nitrogen atmosphere and temperature of 300, 500 and 550 °C, respectively. The structural, electric and optical characteristics were then investigated. All films illustrate strong (002) for ZnO and (335) for Al preferential orientation by using XRD analysis. The lower resistivity can be observed at nitrogen annealing and temperature of 400 °C. The transmittance property of AZO thin film exhibited an excellent transparency in the visible light range. The transmittance reached to nearly 81.4 % for all Al:ZnO film. It can be clearly observed that the grain size of AZO thin film is very uniform by utilizing SEM technology.     

Influence of Si co-doping on magnetic, electrical and optical properties of Ga_(1-x)Mn_xN film grown by MOCVD

A detailed study is presented on magnetic, electrical and optical properties of Ga 1-x Mn x N: Si film grown by metal organic chemical vapor deposition (MOCVD) with high-purity SiH 4 as the Si dopant source. The room-temperature field dependence magnetization and zero-field-cooled (ZFC)/field-cooled (FC) measurements indicate that the film remains room-temperature ferromagnetism and it declines slightly after Si co-doping. However, room-temperature Hall measurements indicate that the electrical property of ...     

水热合成纳米二氧化钛的工业制备研究

本研究以工业级四氯化钛为钛源,首次采用两步反应法,该新方法将第一步引发反应与第二步水热合成相结合进行纳米TiO_2的合成,改进了常用工业级水热合成方法不能有效控制纳米TiO_2粒径的缺点。所采用的原料为工业常用原料,操作简单,过程易控,该方法适合工业放大。经XRD和SEM表征,可知所制备的TiO_2为锐钛矿型;粒径为20 nm,且粒径均匀;经TEM表征可知,颗粒间具有一定的分离空间,具有较好的单分散度,可满足工业技术需求。     

Effects of temperature and pressure on the structural and optical properties of ZnO films grown by pulsed laser deposition

ZnO thin films were deposited on fused silica via pulsed laser deposition (PLD) at substrate temperatures from 300°C to 800°C and ambient oxygen pressures ranging from 10-2 mTorr to 240 mTorr. X-ray diffraction (XRD) and Raman spectra indicated that wurtzite ZnO was obtained in all cases. The highly c-oriented ZnO films were obtained for oxygen pressures above 11 mTorr. The room-temperature photoluminescence (PL) spectra demonstrated that all the films exhibited strong near-band-edge (NBE) emission, while d...     

Structural, optical and electrical properties of CdO/Cd(OH)2 thin films grown by the SILAR method

Successive Ionic Layer Adsorption and Reaction (SILAR) was used to form Cd(OH)₂ thin films from aqueous cadmium–ammonia complex on glass substrates at room temperature and the thermal annealing effect on thin films was studied. The as-deposited films were annealed at 200, 300 and 400 °C for 1 h in an oxygen atmosphere for conversion from Cd(OH)₂ to CdO and change in the structural, optical and electrical properties of the films and the effect of the light on the electrical properties of the films were investigated. The structural and surface morphological properties of the films were studied using X-ray diffraction (XRD) and scanning electron microscopy (SEM). It was found that Cd(OH)₂ phase is converted into the cubic CdO films by annealing. The band gap energy values of films decreased from 3.59 to 2.13 eV through increasing annealing temperature. It was found that the current increased with increasing light intensity and CdO films were more conductive than the as-deposited films.     

Electronic,electrical and thermodynamic properties of Ca5Si3 by first principles calculations and low temperature experimental techniques

A combined experimental and computational study of the Ca₅Si₃ phase is presented. Its’ electronic structure and lattice stability are investigated by first principles methods: four different crystal lattices have been investigated by means of density functional theory (DFT) calculations and pseudopotentials within the generalized-gradient approximation using the VASP code. The Ca₅Si₃ phase is predicted to undergo an high pressure transition: the lattice transition tI32(Cr₅B₃-type) → tI32(W₅Si₃-type) has been predicted by DFT to occur at 14.9 GPa. The electronic and band structure of the tI32 Cr₅B₃-type lattice is calculated and discussed. The Ca₅Si₃ phase ground state structure is predicted to be a metal with a peaked density of states below the Fermi energy and a sharp minimum right above it. Experimentally the low temperature resistivity and heat capacity of the Ca₅Si₃ phase have been measured between 2 and 300 K and discussed in view of our computational predictions and available literature. The Ca₅Si₃ tI32(Cr₅B₃-type) standard pressure polymorph exhibits a metallic temperature dependence of the electric conductivity in agreement with the DFT predictions.     

Effect of annealing and temperature on the NO2 sensing properties of tellurium based films

Influences of temperature and annealing on the electrical and sensing properties toward NO₂ of tellurium based films were investigated. The annealing at temperatures more than 100 °C causes a sharp decrease both of electrical resistance and sensitivity of the films. SEM analyzes indicated that annealing induced structural evolution of the films, including growth of large crystals in the matrix. Temperature-dependent electrical conductivity is strongly affected by presence of an NO₂ environment. The sensitivity toward NO₂, being controlled by gas concentration, decreases with operating temperature increase. On the other hand, the increase of operating temperature leads to a reduction of response–recovery times.

The results are discussed taking into consideration the contributions of grain boundary as well as grain bulk and surface resistance to the total conductivity. It is assumed the surface, including grain boundary, hole-enriched region is formed as a result of dangling bond chalcogen’s lone-pair electron interaction. Chemisorption of NO₂ molecules is accompanied by hole enrichment of the surface and grain boundary region, due to interaction of these molecules with lone-pair electrons.     

Enhanced photocatalytic efficiency by layer-by- layer self-assembly of graphene and titanium dioxide on shrink thermoplastic film

Microsystem Technologies - In this work, reduced graphene oxide/titanium dioxide (rGO/TiO2) composite material was immobilized on shrink thermoplastic film using layer-by-layer (LBL) self-assembly...     

电机电磁线退火温度场仿真分析

以某高速重载列车牵引电机专用电磁线为研究对象,充分考虑退火过程中存在的接触传热、导热、对流传热和辐射传热以及循环风机和测温钢管等影响因素,借助STAR-CCM+并应用流固耦合分析技术对电磁线的退火温度场进行数值模拟.仿真结果与实测结果基本吻合,证明该方法的正确性.给出的退火温度与机械性能的关系可为电磁线退火工艺的优化提供参考.     

A complementary matching technique to reduce the variance of optical and electrical properties of light‐emitting diodes

Abstract— Light‐emitting diodes (LEDs) using phosphor conversion inherently have a wide variation of multiple parameters, including correlated color temperature (CCT), light output power (LOP), and forward voltage VF. A method, based on the formation of LED pairs with complementary characteristics, is presented to produce LED‐based light sources with narrow CCT, LOP, and VF distributions. A weighted matching algorithm was developed to select LED pairs under a multiple selection criteria. Based on the weighted matching algorithm, 96 LEDs were combined to form 48 LED pairs, and it was experimentally demonstrated that the variance of LED CCT and LOP distributions decreased by 93% and 71 %, respectively.     

Laser synthesis of optical media with silver nanoparticles by nanosecond pulses at air

The present work is dedicated to further development of the laser synthesis method for metal nanoparticles formation at air conditions. On the base of complex investigation of processes taking place during laser erosion of metals by intensive nanosecond pulses the method of silver nanoparticles fluxes formation is proposed. By the implantation of silver nanoparticles into liquid media (water or solutions of a polymeric base) the transarent media with silver nanoparticles can be obtained (particularly water colloids and modified polimer films). For the aims of investigation of formed polymeric films the complex diagnostics method is used     

Photocatalytic degradation of formaldehyde by diffuser of solar light pipe coated with nanometer titanium dioxide thin films

The even and transparent nanometer TiO2 thin films named DegussaP25 as photocatalysis deposited on the surface of diffusers of solar light pipe were prepared by sol-gel processing.The rugged side of the diffusers of solar light pipe was coated evenly with DegussaP25 solution for the quality of 1.75 g.The experiments had showed that when the coated side was away from the sun the lighting degree may be reduced compared with that facing the sun.The average reduction was only 3.03%,which would not have a signif...     

Coatings of indium tin oxide nanoparticles on various flexible polymer substrates: Influence of surface topography and oscillatory bending on electrical properties

Abstract— Coatings of indium tin oxide (ITO) nanoparticles on different flexible polymer substrates were investigated with respect to the achievable sheet resistance and their electrical behavior under oscillatory bending. As substrate materials, polyethyleneterephthalate (PET), polyethylenenaphthalate (PEN), polyetheretherketone (PEEK), and polyimide (PI) were chosen, the surface resistances on the different polymer substrates were compared as a function of annealing temperature and surface topography. The surface topography, which has a strong influence on the surface resistance, was characterized by means of a white‐light confocal (WL‐CF) microscope. On the PET substrate, which exhibits the smoothest surface, the coating of ITO nanoparticles shows the lowest sheet resistance of 2 kΩ/□ for a layer thickness of 3 μm and an annealing temperature of 200°C. Furthermore, the electrical behavior of coatings of ITO nanoparticles under oscillatory bending was investigated using a special device. These coatings show a cyclic change of the conductivity which can be explained by an alternating compression and extension of crack flanks under the applied stress. Due to the growing number of cracks with increasing number of cycles, a decrease of the conductivity is observed in the bent state as well as in the balanced state. For a small bending radii, the decrease of the conductivity is stronger due to more cracks caused by the higher tensile stresses in the layer. The electrical behavior of the coatings of the annealed ITO nanoparticles on PET films under oscillatory bending was compared with commercially available sputtered ITO coatings. The annealed coatings of ITO nanoparticles demonstrate better electrical properties under oscillatory bending than coatings of sputtered ITO. The different electrical behavior under oscillatory bending can be related to differences in crack formation.     

SO_2传感器温度特性与精确测量的研究

针对温度对定电位电解SO2传感器(CF—100)输出的影响,利用基于LabVIEW软件开发的虚拟测试仪,结合不同温度下的实际测量数据,得出一定体积分数下传感器的输出与温度的关系,并通过线性拟合对输出结果进行校正,使传感器的输出受温度影响造成的波动降低了90%,大幅提高了测量准确度。     

Enhancement of an immunoassay using platinum nanoparticles and an optical detection

This study proposes a potentially rapid and effective immunoassay using antibody-platinum nanoparticles (Ab-PtNPs) conjugates as a message molecule and a flatbed scanner for the optical scanning and measuring of the immuno-reaction signal. The proposed immunoassay is a sandwich-type immunoassay (three-layer format) along with a silver enhancement reaction, and a signal amplification method was introduced to magnify the detected signal. The signal was the grayscale corresponded to the immuno-reaction, which determined the detection limit and reaction time. Results showed that the rapid silver precipitation phenomenon was catalyzed by Ab-PtNPs conjugates. The color change during the reaction was readily observed by the naked eye and analyzed by an optical flatbed scanner. The relationship between sample concentration and grayscale of signal is discussed. The detection limit (sandwich format assay) for the sample antigen was 0.1 ng/mL which is superior to the detection limit achieved via Au and Ag nanoparticles (AuNPs and AgNPs). Using an optical flatbed scanner, Ab-PtNPs conjugates and a silver enhancement reaction, a novel immunoassay has been constructed.     

Thermal stability, electrical conductivity and ammonia sensing studies on p-toluenesulfonic acid doped polyaniline:titanium dioxide (pTSA/Pani:TiO2) nanocomposites

Electrically conductive p-toluenesulfonic acid (pTSA) doped polyaniline (Pani):titanium dioxide (TiO₂) nanocomposites (pTSA/Pani:TiO₂) were prepared by in situ polymerization of aniline with TiO₂ nanoparticles. Thus formed pTSA/Pani:TiO₂ nanocomposites were characterized by Fourier transform infra-red (FTIR) spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM) and thermogravimetric analysis (TGA). The sensitivity of the nanocomposites towards low concentrations of aqueous ammonia was examined and compared with that of the pure Pani. It was found that the resistivity of pTSA doped nanocomposites increases on exposure to ammonia at room temperature. The nanocomposites were found to possess superior ammonia sensing capacity as compared to pure Pani and it showed linear relationship between the responses and the ammonia concentration. The Fourier transform infrared (FTIR) spectroscopy was used to explain the sensing mechanism. A novel mechanism for the interaction process between the sensing material and ammonia has also been proposed.     

Ga‐doped zinc oxide: An attractive potential substitute for ITO,large‐area coating,and control of electrical and optical properties on glass and polymer substrates

Abstract— Ga‐doped ZnO (GZO) films with thicknesses of 30–560 nm were prepared on glass substrates at 200°C by ion plating with direct‐current arc discharge. The dependences of the characteristics of GZO films on thickness were investigated. All the polycrystalline GZO films, which showed high transmittance in the visible region, were ZnO crystallites with a wurtzite structure highly oriented along the (0002) plane. The resistivity, ρ, of GZO films decreases with increasing film thickness. The highest ρ achieved is 4.4 × 10⁻⁴ Ω‐cm with a carrier concentration, n, of 7.6 × 10²⁰ cm⁻³ and a Hall mobility, μ, of 18.5 cm²/V‐sec, determined by Hall effect measurement for the GZO films with a thickness of 30 nm, and the lowest ρ is 1.8 × 10⁻⁴ Ω‐cm with n = 1.1 × 10²¹ cm⁻³ and μ = 31.7 m²/V‐sec for the GZO film with a thickness of 560 nm. In addition, highly transparent GZO films with thicknesses of 12–300 nm were fabricated on unheated polymethyl methacrylate (PMMA). The ρ of these transparent GZO films decreased from 20 to 4 × 10⁻⁴ Ω‐cm with film thickness.     

Pinecone-shaped ZnO nanostructures: Growth, optical and gas sensor properties.

Pinecone-shaped ZnO nanostructures have been fabricated on Si substrate by pulsed laser deposition. The scanning electron microscope images showed that pinecone-shaped ZnO nanostructure was 6-fold symmetry and has the rough surface on one end. X-ray diffraction, Raman spectra and X-ray photoelectron spectroscopy indicated that the ZnO nanostructures have high crystal quality and a large amount of surface states. Compared with ZnO nanowires and nanobelts, the oxygen gas sensor based on pinecone-shaped ZnO nanostructures has excellent selectivity, fast response and recover, and lower operating temperature. Meanwhile, the response properties are very stable over several circles.