Microstructure and magnetic properties of NiZn ferrite thin films prepared by sol-gel method

Ti^4＋ substitution for Fe^3＋ in Ni0.5Zn0.5Fe2O4 （NZF） ferrite thin films were realized by sol-gel method and annealing at 600℃for 30 min in the air. Crystal structure and lattice constant determination was performed by X-ray diffractometer （XRD）. Surface microstructure was observed by scanning electron microscope （SEM） and atomic force microscope （AFM）, and the magnetic properties were measured by vibrating sample magnetometer （VSM）. XRD analyses of the samples show that Ni0.5＋xZn0.5TixFe2-2xO4 （NZTF） films with x varing from 0 to 0.15 in steps of 0.05 are composed of single phase with spinel structure. And the lattice parameter, particle size and the diffraction intensity of the films increase with substitution of Ti as the result of the larger radius ions entering the lattice. SEM and AFM show homogeneous grain size of each sample, but there is a few differences in grain size with different Ti-substitution contents. As the nonmagnetic Ti^4＋ substitutes Fe^3＋, both the saturation magnetization and coercivity decrease.     

Photoluminescence properties of ZnSe/SiO2 composite thin films prepared by sol-gel method

ZnSe/SiO2 composite thin films was prepared by sol-gel method. XRD results indicate the phase structure of ZnSe particles embedded in ZnSe/SiO2 composite thin films is sphalerite （cubic ZnS）. Spectroscopic ellipsometers were used to investigated the dependences of ellipsometric angle with wavelength of ZnSe/SiO2 composite thin films. The optical constant, thickness, porosity and the concentration of ZnSe of ZnSe/SiO2 thin composite films were fitted according to Maxwell-Garnett effective medium theory. The thickness of ZnSe/SiO2 composite thin thin films was also measured through surface profile. The photoluminescence properties of ZnSe/SiO2 thin composite thin films was investigated through fluorescence spectrometer. The photoluminescence results show that the emission peak at 487 nm （2.5 eV） is excited at 395 nm corresponds to the band-to-band emission of sphalerite ZnSe crystal（2.58 eV）. The strength free exciton emission and other emission peaks correlating to ZnSe lattice defect were also observed.     

Preparation and properties of CdS thin films grown by ILGAR method

CdS thin films were deposited by the ion layer gas reaction (ILGAR) method. Structural, chemical, topographical development as well as optical and electrical properties of as-deposited and annealed thin films were investigated by XRD,SEM, XPS, AFM and UV-VIS. The results showed that the thin films are uniform, compact and good in adhesion to the substrates, and the growth of the films is 2.8 nm/cycle. The evolution of structure undergoes from the cubic structure to the hexagonal one with a preferred orientation along the (002) plane after annealing at 673 K. An amount of C, O and C1 impudries can be reduced by increasing the drying temperature or by annealing in N2 atmosphere. It was found that the band gap of the CdS films shifts to higher wavelength after annealing or increasing film thickness. The electrical resistivity decreases with increasing annealing temperature and film thickness.     

Zn靶与掺铝ZnO靶共溅射制备ZnO:Al薄膜及其性能

采用Zn靶和ZnO(掺2%Al2O3(质量分数))陶瓷靶在玻璃衬底上共溅射沉积Al掺杂ZnO薄膜,即ZnO:Al透明导电薄膜,研究Zn靶溅射功率(0～90 W)和衬底温度(室温、100℃和200℃)对薄膜结构、形貌、光学和电学性能的影响。结果表明:按双靶共溅射工艺制备的ZnO:Al薄膜的晶体结构均为六角纤锌矿结构,且随着Zn靶溅射功率的增加,薄膜的结晶质量呈现出先改善后变差的规律,薄膜中的载流子浓度逐渐升高,电阻率逐渐降低,而薄膜的光学性能受其影响不大;随着衬底温度的升高,薄膜的结晶性能得到改善,薄膜的可见光透过率增强,电阻率降低。     

Optical properties of nanosized ZnO films prepared by sol-gel process

Nanosized ZnO films were prepared by sol-gel process on quartz substrates. The effects of sol concentration and annealing temperature on the surface morphology, microstructure and optical properties of the films were investigated. The results show that the sols remain stable and usable for spin-coating within 7 d. The ZnO films have a homogeneous and dense surface with grain size about 30 nm. The ZnO thin film annealed at 500 ℃ for 1 h from the sol with Zn concentration of 0.8 mol/L shows an average transmittance of 94% in visible wavelength range. The optical band gaps in ZnO films by various annealing temperatures are from 3.265 eV to 3.293 eV. The violet emission located at 438 nm is probably due to the recombination transitions relating to the interface traps at the grain boundaries.     

溶胶-凝胶旋转涂布法制备的多孔纳米二氧化钛膜的结构和光学性能(英文)

采用溶胶凝胶旋转涂布技术在石英基质上沉积三种不同厚度的TiO2薄膜,其厚度分别为174、195和229nm。沉积得到的薄膜是由尺寸为19~46nm的纳米微晶组成的,并具有较高的多孔结构。测定了薄膜的光学常数,得到了迄今为止报道的最低折射率1.66,并对所得结果进行了讨论。     

Preparation of ZnO crystal by sol-gel method

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Conductive and transparent Bi-doped ZnO thin films prepared by rf magnetron sputtering

Bi-doped ZnO thin films were grown on glass substrates by ratio frequency (rf) magnetron sputtering technique and followed by annealing at 400 °C for 4 h in vacuum (~ 10^− 1 Pa). The effect of argon pressure on the structural, optical, and electrical properties of the Bi-doped films were investigated. The XRD patterns show that the thin films were highly textured along the c-axis and perpendicular to the surface of the substrate. Some excellent properties, such as high transmittance (about 85%) in visible region, low resistivity value of 1.89 × 10^− 3 W cm and high carrier density of 3.45 × 10²⁰ cm^− 3 were obtained for the film deposited at the argon pressure of 2.0 Pa. The optical band gap of the films was found to increase from 3.08 to 3.29 eV as deposition pressure increased from 1 to 3 Pa. The effects of post-annealing treatments had been considered. In spite of its low conductivity comparing with other TCOs, Bi-doping didn't appreciably affect the optical transparency in the visible range of ZnO thin films.     

溶胶-凝胶法制备TiO2-SiO2系亲水性薄膜的研究

采用溶胶-凝胶(sol-gel)法在陶瓷釉面砖表面制备了TiO2-SiO2系亲水性薄膜.利用XRD、AFM、FTIR、热显微镜润湿角测角仪等,研究了SiO2添加量对薄膜的微结构和亲水性等的影响.结果表明:薄膜中TiO2晶粒尺寸随着SiO2含量的增加而减小;TiO2和SiO2分别单独成相,并有Ti-O-Si键形成,存在部分复合氧化物,在光照条件下,由于取代反应,复合氧化物的表面易形成Lewis酸,薄膜表面吸附的羟基含量增多且稳定,SiO2摩尔分数为0.4时,润湿角小于5°,薄膜的超亲水状态可在停止光照后长时间存在.     

Effect of annealing treatment onoptical and electrical properties of ZnO films

The ZnO-Al films were prepared by R. F. magnetron sputtering system using a Zn-Al target (with purity of 99.99 %). The obtained films were characterized by X-ray diffraction, SEM and optical and electrical measurements. The experimental results show that the properties of ZnO films can be further improved by annealing treatment. The crystallinity of ZnO films becomes better, and the optical gap energy is decreased, but thermoelectric power is enhanced after heat treatment. The optical gap energy decreases from 3.75 eV to 3.68 eV when the annealing temperature increases from 25℃ to 400℃. This can be ascribed to the decrease of carrier concentration, resulting in Burstein shift.     

Preparation of delafossite-type CuCrO2 films by sol-gel method

High-quality c-axis oriented delafossite-type CuCrO₂ films were successfully prepared by a simple sol-gel method. The microstructure, optical properties as well as room temperature resistivity were studied. It was found that the grain sizes of CuCrO₂ films pretreated with different temperatures are different; the films were smooth and consisted of fine particles. The maximal transmittance of CuCrO₂ films can reach 70% in the visible region. Optical transmission data of CuCrO₂ films indicate a direct band gap and an indirect-gap of about 3.15 eV and 2.66 eV, respectively. The carrier mobility of the films pretreated at 300 °C is smaller than that of the films pretreated at a higher temperature, because of the stronger carrier scattering.     

Effect of annealing treatment on the structural, optical, and electrical properties of Al-doped ZnO thin films

Highly conductive and transparent Al-doped ZnO (AZO) thin films were prepared from a zinc target containing Al (1.5 wt.%) by direct current (DC) and radio frequency (RF) reactive magnetron sputtering. The structural, optical, and electrical properties of AZO films as-deposited and submitted to annealing treatment (at 300 and 400 ℃, respectively) were characterized using various techniques. The experimental results show that the properties of AZO thin films can be further improved by annealing treatment. The crystallinity of ZnO films improves after annealing treatment. The transmittances of the AZO thin films prepared by DC and RF reactive magnetron sputtering are up to 80% and 85% in the visible region, respectively. The electrical resistivity of AZO thin films prepared by DC reactive magnetron sputtering can be as low as tering have better structural and optical properties than that prepared by DC reactive magnetron sputtering.     

Influence of oxygen gas content on the structural and optical properties of ZnO thin films deposited by RF magnetron sputtering at room temperature

Zinc oxide (ZnO) thin films were deposited on sapphire (0001) substrates at room temperature by radiofrequency (RF) magnetron sputtering at oxygen gas contents of 0%,25%,50% and 75%,respectively.The influence of oxygen gas content on the structural and optical properties of ZnO thin films was studied by a surface profile measuring system,X-ray diffraction analysis,atomic force microscopy,and UV spectrophotometry.It is found that the size of ZnO crystalline grains increases first and then decreases with the increase of oxygen gas content,and the maximum grain size locates at the 25% oxygen gas content.The crystalline quality and average optical transmittance (>90%) in the visible-light region of the ZnO film prepared at an oxygen gas content of 25% are better than those of ZnO films at the other contents.The obtained results can be attributed to the resputtering by energetic oxygen anions in the growing process.     

ZnO nanoneedles fabricated by a simple approach and their optical properties

Spoke-like ZnO nanoneedles have been successfully synthesized at the ambient pressure through thermally oxidizing Zn powders containing Au nanoparticles. X-ray diffraction analysis indicates that the ZnO nanoneedles have a hexagonal wurtzite structure of the crystalline ZnO. The morphology of the products was examined by FESEM. The photoluminescenee(PL) spectrum under 325 nm exhibits both an UV emission and a green emission. It is interesting to note that the heating rate plays a key role in the synthesis of ZnO nanoneedles. Based on this discovery we propose to explain the special growth behavior as novel mechanism that a large temperature gradient and Au nanoparticles simultaneously result in the spoke-like ZnO nanoneedles growth.     

电化学沉积Nd掺杂ZnO薄膜的结构和光学性质的研究

用电化学沉积方法制备出了Nd掺杂的ZnO薄膜,并研究其结构和光学性质。X-射线衍射谱的结果表明Nd3 替代Zn2 进入到ZnO晶格中,并没有引起杂相的出现。吸收谱的分析表明,随着掺杂浓度的增大,吸收峰向短波长方向移动 ,即发生蓝移。光致发光谱的结果表明随着Nd3 掺杂浓度的增大,紫外峰强度减小,可见光部分强度增大了。     

Development on transparent conductive ZnO thin films doped with various impurity elements

A general review of recent research progress in fabricating transparent conductive ZnO thin films by means of intentional doping and codoping with In,Ga,Al,Mg,Li,F,H,N,and P,divided into metals and nonmetals,is presented in this article.The main emphasis is placed on introducing and discussing the recent research achievements on the mechanisms of the incorporation of these impurities,and their effects on the electrical and optical properties.Lastly,this article concludes with a summary of the present state of investigations on doping elements in fabricating functional ZnO thin films for photoelectric applications,and with our personal view of the perspective of future studies on doped ZnO thin films.     

Preparation and characterization of ZnO/Cu/ZnO transparent conductive films

ZnO/Cu/ZnO transparent conductive thin films were prepared by RF sputtering deposition of ZnO target and DC sputtering deposition of Cu target on n-type (001) Si and glass substrates at room temperature. The morphology, structure, optical, and electrical properties of the multilayer films were characterized by field emission scanning electron microscope (FESEM), X-ray diffraction (XRD), UV/Vis spectrophotometer, and Hall effect measurement system. The influence of Cu layer thickness and the oxygen pressure in sputtering atmosphere on the film properties were studied. ZnO/Cu/ZnO transparent conductive film fabricated in pure Ar atmosphere with 10 nm Cu layer thickness has the best performance: resistivity of 2.3×10-4 Ω·cm, carrier concentration of 6.44×1016cm-2 , mobility of 4.51cm2·(V·s)-1 , and acceptable average transmittance of 80 % in the visible range. The transmittance and conductivity of the films fabricated with oxygen are lower than those of the films fabricated without oxygen, which indicates that oxygen atmosphere does not improve the optical and electrical properties of ZnO/Cu/ ZnO films.     

An investigation on linear optical properties of dilute Cr doped ZnO thin films synthesized via sol-gel process

Cr doped ZnO thin films were prepared via sol-gel method. The effects of dopant concentration (0%, 1.5% and 3%) annealing temperature and film thickness on UV-Vis spectra of prepared films were investigated. Also, the thickness and surface topology of thin films were investigated by thickness profile meter (DEKTAK) and Atomic Force Microscopy (AFM), respectively. In addition, the band gap and Urbach energy of prepared films were calculated completely for the samples. The results showed that by increasing the dopant concentrations, the microstrain of the prepared thin film structures also increases while the band-gap values decrease. Meanwhile, an increase in annealing temperature makes a decrease in band gap and microstrain of thin films. The increase in thickness resulted in red shift in band gap and reduction in interior microstrains.     

Doping and annealing effects on ZnO:Cd thin films by sol-gel method

In this article, ZnO:Cd films were successfully deposited on glass substrates by a sol-gel technique. The influence of doping concentration and annealing temperature effects was carefully investigated. All films exhibited c-axis preferential orientation and optical transparency with visible transmittance >80%. The minimum room temperature resistivity of 0.0341 Ω cm was obtained with 10 at.% Cd doping under 600 °C annealing temperature. The optical band gap of ZnO:Cd film was reduced as Cd doping concentration increased, while the band gap increased with the increase of annealing temperature.     

Synthesis of hexagonal barium ferrite nanoparticle by sol-gel method

M-type Ba hexaferrites were successfully synthesized by sol-gel method. Several synthesizing factors, such as pH value, citric acid/metal ion ratio, and dispersion agent were mainly discussed. Fine and pure powders of BaFe12O19 were optimally synthesized under the conditions of the pH value is 7 and citricacid/metal ion ratio is 3. The X-ray diffraction analysis demonstrates that no impurity is observed in the synthesized powders after presintered at 450 ℃ and calcinated at 1100 ℃. SEM observations indicate that the size of the synthesized BaFe12O19 powders is small and uniform distribution. It can also be learned from SEM that the co-synthesizing sol-gel method can be in favor ofthe formation of finer particles.