Dry etching mechanism of copper and magnetic materials with UV illumination

To better understand the dry etching of copper and magnetic materials with UV illumination an etch mechanism is proposed based on the subprocesses occurring in an inductively coupled plasma (ICP) reactor. The photo-dissociation of Cl₂ provides chlorine-enriched environment near the surface, and UV photons enhance the surface reaction, leading to fast formation of metal chlorides on the surface with low activation energy. The overall etching process of metals with UV illumination is limited by absorption capacity of UV radiation by reaction products. The proposed etch mechanism also showed the potential gaseous etch products are CuCl, CuCl₂, Cu₂Cl, Cu₂Cl₂, Cu₂Cl₃, Cu₃Cl₂ and Cu₃Cl₃, while the dominant gas species are CuCl₂ and Cu₂Cl₃ with UV illumination. The ICP etching of magnetic materials in Cl₂/Ar discharges with UV illumination showed no enhancement in etch rate for NiFe, but a substantial enhancement for NiFeCo mainly due to the lower binding energy of NiFeCo relative to NiFe.     

Sensing characteristics of dc reactive sputtered WO3 thin films as an NOx gas sensor

In order to apply WO₃ thin films to the NO_x gas sensor, WO₃ thin films (3000 Å) were fabricated by using dc reactive sputtering method on alumina substrate and assembled as a unit of an NO_x gas sensor by adopting a patterned heater on the back side of substrate. The deposition temperatures of WO₃ thin film were changed from 200°C to 500°C, and then post-annealed for the crystallization for 4 h at 600°C. There were no WO₃ phases at the substrate temperature of 200°C, but the crystalline phases of WO₃ thin film were appeared with the increase of substrate temperature from 200°C to 500°C. The post-annealing of as-deposited WO₃ thin films at 600°C resulted in the enhancements of crystallinity, but it was observed that the quality of the final phases severely depends on the initial formation of phase during deposition. From the SEM images, crack free morphologies were found, which was different from the room temperature growth films. The sensitivity (R_gas/R_air) of as-deposited thin films was ranged from 4 to 10 for the 5 ppm NO test gas at the measuring temperature of 200°C. However, after post-annealing process at the temperature of 600°C, the sensitivities were increased around the values of 70–180 at the same test condition. These results show the WO₃ thin films need to be processed at least at the temperature of 600°C for the well-improved sensitivity against NO_x gas. It was also observed that the recovery rate of a sensing signal after measuring sensitivity was faster in the in-situ sputtered films than in the evaporated films or room temperature sputtered films.     

Design and synthesis of a novel red electroluminescent dye

A novel type of red organic electroluminescent (EL) dye, DCN with CN groups and amine groups for an emission layer of electroluminescent devices was designed and synthesized. Two kinds of EL devices were fabricated. Devices with a single-layer type, indium tin oxide/DCN/MgAg and a double-layer device, indium tin oxide/DCN/OXD/MgAg were fabricated. DCN dye shows high EL efficiency over 1% in red color even in the single-layer device.     

ZnS:Er量子点材料制备及其受激发光特性研究

在水性介质中,制备了ZnS：Er量子点,并对其的X射线（XRF）谱、X射线衍射（XRD）谱、透射电子显微镜（TEM）图像和光致发光（PL）谱进行了研究,确定了所制备的ZnS：Er量子点材料中Er的浓度,观测到ZnS：Er量子点呈粒径为4nm的近球型结构。利用LD激发,在LD不同电流强度下得到ZnS：Er量子点从波长1500nm到1650nm的宽谱发射,并随着电流强度的增加ZnS：Er量子点的发射强度明显增加,当电流强度达到1．5A时,1545nm波长处的发射峰更明显。     

改进的飞秒激光加工微型光波导方法

分析了垂直式加工中加工区域光强分布不对称的原因,从理论上总结出改进这种不对称的方法。在分析了仅引入单个透镜就能实现这一改进的可行性后,实验验证了这种改进方法。未改进之前加工出的光波导其端口两个方向直径之比为10:1,甚至更高;而改进后的比例则非常接近1:1。通过对光强不对称的改进,该方法有光路简单,无能量损失的优势。     

Near-infrared emission from PbS quantum dots in polymer matrix

PbS quantum dots were prepared in the aqueous medium from readily available precursors. The shape of the particles isapproximately spherical, and the average particle size observed from HRTEM image was 7-8 nm. We applied PbS quantumdots and PMMA polymer to fabricate PbS quantum dots-PMMA composites, and investigate the photoluminescence PbSquantum dots in PMMA matrix with different mass ratio. PbS quantum dots in PMMA matrix have broad emission be-tween 900 nm and 1 500 nm and photoluminescence peak at 1 179 nm. Additionally, the photoluminescence intensityincreases with increasing the dopant concentration. PbS quantum dots-PMMA polymer composites can be potentially usedfor polymer optical fiber and electroluminescence (EL) in optical communication.     

Pulsed digital micro-holography of femto-second order by double-wavelength recording

Double-wavelength recording used in a pulsed digital micro-holographic system to record ultra-fast processing of the order of femto-second is reported for the first time, where a BBO crystal is used to generate harmonic wave of the incident laser wave, and both of the basic and the frequency doubled waves are time-delayed and introduced to a Michelson’s interferom- eter to record two sub-holograms with different spatial frequencies on a single frame of a CCD. In the experiment, an ultra- fast dynamic process of air ionization induced by a single femto-second laser pulse is recorded with holography by this system, and both of intensity and phase difference images digitally reconstructed are obtained through Fourier transforma- tion and digital filtering, which show clearly the dynamic process of formation and propagation of the plasma, with a time resolution of the order of femto-second.     

Multi-wavelength fiber laser based on broadband fiber grating and HiBi fiber loop mirror

Multi-wavelength fiber lasers have attracted a lot of in- terest in recent years because of its potential applications in optical wavelength division multiplexing (WDM) systems, fiber sensors, and other fiber-optics instruments. Because of the predominant…     

Unveiling crystallization mechanism for controlling nanocrystalline structure in glasses

Controlling nanocrystalline structure in glasses renders the exploration of new composite multiphase (glass-ceramic) materials with novel functionalities that determined by the precipitated nanocrystals and residual glassy matrix. Previous microstructural investigation of glass-ceramics focused only on one aspect of nanocrystalline structures, e.g., nano-polycrystalline or single nanocrystalline. The recognition of the microscopic mechanism of nanostructure formation in glasses is absent. Here, we use advanced microscopic techniques to show the formation of different nanocrystalline structures composed of nano-polycrystals and single nanocrystals in 80GeS₂·20In₂S₃ and 72.5GeS₂·14.5Sb₂S₃·13RbCl glasses, respectively. Crystallization mechanism for controlling the nanocrystalline structure in glasses was revealed to depend on whether the glass network former participates in crystallization process. The results may shed light not only on glass crystallization mechanism, but also on the fundamental nature of the network structure of chalcogenide glasses.     

基于ATM交换结构的Hopfield神经网络调度算法

针对ATM交换结构,采用输入缓冲和每条入线在同一个时隙内可传送多于一个信元的策略,利用神经网络具有的实时性、高度并行处理能力和易于电路或光电技术实现等特点,提出了一种Hopfield神经网络调度算法。实验仿真比较表明,该方法不但大大提高了吞吐率,消除了队头阻塞造成的性能恶化,而且降低了信元丢失率和较大程度地降低了平均信元时延,提高了ATM交换结构的性能,实现了信元的优化调度。